Preparation of silicone compositions and materials

Abstract

This disclosure relates to a method for the preparation of a curable silicone composition comprising preformed silicone elastomeric particulates. The method includes the steps of chemically tuning the preformed silicone elastomeric particulates by chemically capping reactive groups in or on the preformed silicone elastomeric particulates to render preformed silicone elastomeric particulates chemically unreactive with other components in the curable silicone composition, introducing a polyorganosiloxane to penetrate and swell said preformed silicone elastomeric particulates and mixing same with the other components of the curable silicone composition. It also relates to the resulting compositions and the cured elastomeric material resulting from the cure of said compositions.

Description

[0001] PREPARATION OF SILICONE COMPOSITIONS AND MATERIALS This disclosure relates to a method for the preparation of a curable silicone composition comprising preformed silicone elastomeric particulates. The method includes the steps of chemically tuning the preformed silicone elastomeric particulates by chemically capping reactive groups in or on the preformed silicone elastomeric particulates to render preformed silicone elastomeric particulates chemically unreactive with other components in the curable silicone composition, introducing a polyorganosiloxane to penetrate and swell said preformed silicone elastomeric particulates and mixing same with the other components of the curable silicone composition. It also relates to the resulting compositions and the cured elastomeric material resulting from the cure of said compositions. Silicone elastomers may be prepared via numerous routes including by condensation cure processes, sometimes referred to as room temperature vulcanisable processes which are used to make products such as sealants, caulks and adhesives and by high temperature vulcanization methods such as via a hydrosilylation (addition) cure process or a free-radical cure process to make products such as molded elastomeric parts, seals, gaskets, connectors, coatings, adhesives and encapsulants. Condensation curable room temperature vulcanisable (RTV) organosiloxane compositions cure at room temperature in the presence of moisture and are usually obtained by mixing a polydiorganosiloxane based polymer having hydroxyl or hydrolysable reactive groups, with a suitable silane (or siloxane) based cross-linking agent in the presence of one or more fillers and a curing catalyst. These compositions are typically either prepared in the form of one-part compositions curable upon exposure to atmospheric moisture at room temperature or two-part compositions curable upon mixing at room temperature and pressure. Silicone rubber compositions which are curable by hydrosilylation (addition) reactions are typically prepared by initially making a silicone rubber base composition by mixing polydiorganosiloxane polymers containing at least two alkenyl (or alkynyl) groups per molecule with reinforcing silica fillers. Once the silicone rubber base composition has been prepared, a cross-linker in the form of an organosilicon compound having at least two, alternatively at least three Si-H groups per molecule and hydrosilylation catalyst(s) may be added to the base, in order to provide a hydrosilylation curable composition. However, usually commercial compositions are produced in multiple parts, typically in two-parts, to prevent premature cure in storage prior to use. In such two-part compositions, one part, often referred to as Part A, comprises the pre-prepared base and a hydrosilylation catalyst and the second part, often referred to as Part B, comprises pre-prepared base and the cross-linker(s). As can be seen the preparation of hydrosilylation and RTV elastomers involve very different cure chemistries and as such whilst potentially attractive, these different cure chemistries create issues for preparing hybrid hydrosilylation and RTV elastomers, as, for example, the condensation catalysts used for RTV cure can poison platinum (Pt) catalysts in the hydrosilylation cure process and potentially create major safety hazards associated with hydrogen gas (H2) generation. Therefore, mixing uncured hydrosilylation and RTV ingredients in a single composition is challenging and potentially dangerous. Furthermore, the hydrosilylation cross-linkers are generally provided in non-stoichiometric amounts and are usually in molar excess, resulting in the presence of unreacted Si-H groups in hydrosilylation cured silicone rubber and condensation cured silicone materials contain unreacted hydroxyl and / or alkoxysilyl groups present in the cured material. Silicone elastomeric particulates can be prepared from compositions of new silicones polymers and other ingredients as described above. Newly made particulates used as preprepared silicone elastomeric particulates herein may be made from condensation cured (RTV) silicone elastomer compositions or prepared from hydrosilylation curable silicone compositions, peroxide free-radical cure silicone compositions or UV cure silicone compositions any of which may be obtained via their usual curing process into slabs / lumps or the like and then are physically (e.g. mechanically) ground, attrited or otherwise reduced in size into discrete particulates using a grinding device as described elsewhere herein or wherein the curable silicone composition may be cured into particulates by spraying using a spraying device such as a spray drier; or by dispersed and curing the compositions in an aqueous surfactant solution. The latter are often preferred due to their ability to form spherical cured silicone particulate. Preformed silicone elastomeric particulates can alternatively be prepared as a result of physical recycling or reclamation of silicone materials at the end of their use. Examples of recycled and / or reclaimed materials that can be reduced to such preformed silicone elastomeric particulates include but are not restricted to post-industrial scrap or waste rubber, pre-consumer scrap or waste rubber, or post-consumer scrap or waste rubber. Given they are thermoset materials, silicone elastomers cannot be melted and reprocessed into polymers which are suitable to be used in their intended applications and as such it is difficult to provide an effective recycling and / or reclaiming alternative to incineration or landfilling as an end-of-life option to meet the desired “carbon footprint” reduction targets increasing found in the manufacturing industry today. There are two main method types for recycling / reclaiming elastomeric materials these tend to be via “chemical processes” such as pyrolysis, chemical degradation and chemical reversion and by “physical processes”, i.e., mechanical processes such as mechanical reclaiming, thermo-mechanical reclaiming and cryo-mechanical reclaiming and wet / solution grinding methods. Given silicone elastomers are thermoset materials chemical recycling of silicone elastomers is not ideal for reclaiming / recycling requires significant separation and often generate solid residues that are typically of low value. It is known however that particulates made from elastomeric silicone materials may be prepared and one means of achieving this is by recycling and / or reclaiming. That said, such recycled and / or reclaimed silicone elastomeric particulates are typically incorporated as fillers in conjunction with a binder material that serves as a matrix. The binder can be either a new silicone composition or an organic polymer material that can also be combined with an inorganic mixture such as an asphaltic or cementitious mixture and serves the function of entrapping and / or encapsulating the discrete particles. However, they have not been considered useful in valuable applications because of their inconsistency and variability in performance and therefore the value proposition for such recycled and / or reclaimed silicone elastomeric particulates is poor with the particulates only being deployed in lower value applications, lowering economic and technological incentives for reuse, as a result of: (i) poor incorporation of the silicone elastomeric particulates within the binder matrix; (ii) Interfacial adhesion and binding between the silicone elastomeric particulates and matrix being typically poor such that the preformed silicone elastomeric particulates can serve as defects in the matrix, creating voids, surface protrusions or other heterogeneities in the matrix, resulting in inferior properties to new silicone elastomers. There is provided herein a method of preparing a curable silicone composition comprising the steps of (1) obtaining preformed silicone elastomeric particulates (e)(i) having an average unswollen particle size of 1 mm or less, cured by a predetermined cure process; (2) chemically tuning said preformed silicone elastomeric particulates (e)(i) by mixing the preformed silicone elastomeric particulates (e)(i) with a capping agent in the form of a compound having a single reactive chemical group (e)(iii) which will undergo a chemical reaction with anticipated residual chemical groups in or on said preformed silicone elastomeric particulates (e)(i) and allowing same to react for a period of time; to provide chemically tuned preformed silicone elastomeric particulates (e)(i); (3) optionally isolating said chemically tuned preformed silicone elastomeric particulates (e)(i); (4) mixing the chemically tuned preformed silicone elastomeric particulates (e)(i) with an organopolysiloxane polymer swelling agent (e)(ii) having a zero-shear viscosity of less than or equal to (≤) 15,000 mPa.s at 25oC for a defined period to enable said organopolysiloxane polymer swelling agent (e)(ii) to penetrate and swell said chemically tuned preformed silicone elastomeric particulates (e)(i) to form component (e); (5) forming a step (5) mixture by mixing component (e) from step (4) into at least part of a curable silicone composition; (6) if required mixing the step (5) mixture with the remainder of said curable silicone composition. In one embodiment Step (4), Step (5) and optionally step (6) may be undertaken as a single step. In another embodiment Step (2), Step (4), Step (5) and optionally step (6) may be undertaken as a single step. There is also provided a curable silicone composition which is the product of the above method. There is also provided a curable silicone composition obtained or obtainable by a method comprising steps (1) to (6) as described above. In one embodiment Step (4), Step (5) and optionally step (6) may be undertaken as a single step. In another embodiment Step (2), Step (4), Step (5) and optionally step (6) may be undertaken as a single step. There is also provided a cured silicone material which is the cured product of the curable silicone composition. There is also provided a use of a compound having a single reactive chemical group (e)(iii) to chemically tune preformed silicone elastomeric particulates (e)(i) in a method to make a curable silicone composition in accordance with the above method in steps (1) to (6) In one embodiment Step (4), Step (5) and optionally Step (6) may be undertaken as a single step, alternatively Step (4), Step (5) and Step (6) are undertaken as a single step. In another embodiment Step (2), Step (4), Step (5) and optionally step (6) may be undertaken as a single step, alternatively Step (2), Step (4), Step (5) and step (6) are undertaken as a single step. In one embodiment the aforementioned silicone elastomeric particulates in each of the above are physically recycled and / or reclaimed silicone elastomeric particulates (e)(i). The terms “recycling” and “reclaiming” as used herein are intended to define the function of recovering and converting waste materials into new materials and usable products. The term “chemical tuning” is, for the disclosure herein intended to describe the process in which reactive groups on or within preformed silicone elastomeric particulates are exposed to one or more reactive compounds in order to change the chemical nature, of the particulates e.g.: (i) when the preformed silicone elastomeric particulates were prepared by a hydrosilylation cure process, the resulting particulates may have an excess of Si-H groups either on the surface or within the particulates and these can be passivated by interaction with unsaturated compounds having for example one alkenyl, e.g., vinyl group per molecule and compounds which is often undertaken with a molar excess of cross-linking Si-H groups; or (ii) when the preformed silicone elastomeric particulates were prepared by a condensation cure process, the resulting particulates may have an excess of alkoxy groups either on the surface or within the particulates and these can be passivated as above or alternatively given more reactive groups by interaction with for example a suitable alkoxy silane provided with the groups desired to be present on or in the particulates. The term average unswollen particle size is intended to mean the average particle size of particulates irrespective to their method of preparation prior to mixing with a “swelling agent” otherwise identified as component (e)(ii) and / or organopolysiloxane polymer (e)(ii). For example, in the case of physically recycled and / or reclaimed silicone elastomeric particulates (e)(i) it is the average particle size of particulates subsequent to physical recycling and / or reclaiming the source of the silicone elastomer particulates (e)(i) and prior to mixing with a “swelling agent” otherwise identified as component (e)(ii) and / or organopolysiloxane polymer (e)(ii). In one embodiment the source compositions from which the preformed silicone elastomeric particulates (e)(i) are derived was a condensation curable room temperature vulcanisable (RTV) organosiloxane composition, a peroxide cure composition or a hydrosilylation curable silicone rubber composition, alternatively a hydrosilylation curable silicone rubber composition. Hence, the predetermined cure process was a condensation cured process, a peroxide cured process or a hydrosilylation cured process. In the case of hydrosilylation cured preformed silicone elastomeric particulates (e)(i), it is well known that most hydrosilylation cured silicone rubber materials are prepared from compositions containing a non-stoichiometric molar ratio of unsaturated silicone polymer and cross-linker. Usually the Si-H groups of the cross-linker are in molar excess compared to unsaturated groups (e.g., vinyl) of the polymer, i.e. the molar ratio of silicone bonded hydrogen (Si-H groups) to unsaturated groups such as vinyl is greater than 1 : 1, i.e., Si-H : Vi > 1 : 1. Indeed, having a molar excess of silicone bonded hydrogen (Si-H groups) is crucial for hydrosilylation cured silicone rubber to fully cure due to the inherent structural variation present in polymers. However, the presence of excess Si-H groups in the resulting hydrosilylation cured silicone rubbers used a source for preformed silicone elastomeric particulates (e)(i) can pose some potential challenges for their incorporation into a curable silicone composition, especially when incorporating hydrosilylation cured preformed silicone elastomeric particulates (e)(i) into curable silicone compositions. When preformed silicone elastomeric particulates (e)(i) are obtained from a hydrosilylation cured silicone rubber source catalysed using a platinum family-based catalyst, if such preformed silicone elastomeric particulates (e)(i) are dispersed in a hydrosilylation curable silicone rubber composition, the preformed silicone elastomeric particulates (e)(i) may react with the alkenyl groups, e.g. vinyl groups in the hydrosilylation curable silicone rubber composition during cure to form chemical bonds between the resulting hydrosilylation cured silicone rubber and the preformed silicone elastomeric particulates (e)(i). Whilst in some cases these chemical bonds may be advantageous in improving the integration of the preformed silicone elastomeric particulates (e)(i) into the composition and subsequently cured material preventing flaking of preformed silicone elastomeric particulates (e)(i). However, chemical crosslinking between the preformed silicone elastomeric particulates (e)(i) and the composition may also create localized regions of increased crosslink density. These localized regions of increased crosslink density may be stiffer / harder than the corresponding bulk phase and can act like network defects that initiate crack nucleation and growth under deformation. Such localized high crosslink density regions are particularly a challenge in systems where the cured silicone material and preformed silicone elastomeric particulates have similar Shore hardness values, as these interfacial regions can have a Shore hardness that exceeds than both individually, thereby having significantly lower elongation at break. Furthermore, residual Si-H groups in hydrosilylation cured preformed silicone elastomeric particulates (e)(i) may pose long term pot life issues. Since there is residual Si-H in these particulates, these must not be added into compositions containing the catalyst when in multiple parts before use to prevent hydrosilylation cure during storage. Similarly, in the case of condensation cured preformed silicone elastomeric particulates (e)(i) problems and issues can occur if the particulates are derived from condensation cured materials such that they contain excess -OH and / or alkoxy groups. Hence, the provision of the method herein provides a means of avoiding such issues allowing for the incorporation of preformed silicone elastomeric particulates (e)(i) in silicone materials and it will minimise the formation of localized regions of high crosslink density and thus improves elongation at break. Furthermore, the ability to penetrate and swell the preformed silicone elastomeric particulates (e)(i) with an organopolysiloxane polymer swelling agent (e)(ii) as described above, results in the formation of interpenetrating networks between the new silicone composition and the preformed silicone elastomeric particulates, resulting in of the presence of preformed silicone elastomers of varying origin without substantial degradation in mechanical properties (and potentially even “upcycling” through improved properties) of the resulting compositions and materials herein. This has a direct benefit on the Life Cycle Assessment (LCA) of the curable silicone compositions by replacing carbon dioxide equivalence which goes into the making of the ingredients which go into curable silicone composition with a mechanically recycled material that does not require capital- and energy-intensive molecular level purification steps like distillation. Obtaining preformed silicone elastomeric particulates (e)(i) The Preformed silicone elastomeric particulates (e)(i) may be made as new particulates or may be derived from a recycling / reclaiming process derived from any suitable source such as post-industrial or post-consumer waste mainly obtained from condensation cured (RTV) silicone elastomers formerly used as adhesives, refrigerant spacers, potting agents coatings and sealants such as weatherproofing sealants and coatings and / or tire sealants or silicone rubber elastomers prepared from hydrosilylation curable compositions or peroxide free-radical cure compositions, which elastomers may have been used in applications such as airbag coatings, gaskets and seals adhesives, coatings, foams, molded rubber articles, hoses and tubing like medical tubing, encapsulants and potting agents or the like. The original elastomer and the resulting physically recycled and / or reclaimed silicone rubber particulates may be dense or have inclusions or voids, as in foams. However, silicone elastomers made from any suitable cure system may be utilised as the source of preformed silicone elastomeric particulates. Newly made particulates used as preprepared silicone elastomeric particulates herein may be made from condensation cured (RTV) silicone elastomer compositions or prepared from hydrosilylation curable compositions or peroxide free-radical cure compositions which may be obtained via their usual curing process into slabs / lumps or the like and then are mechanically ground using a grinding device as described elsewhere herein or wherein the curable silicone composition may be cured into particulates by spraying using a spraying device such as a spray drier; or by dispersed and curing the compositions in an aqueous surfactant solution. The latter are often preferred due to their ability to form spherical cured silicone particulate. When the preformed silicone elastomeric particulates are the result of physical recycling or reclamation. Physical recycling methods are utilised to transform silicone elastomers into powders, granules, crumbs, or pellets (referred to collectively herein as “particulates”). The source of the silicone elastomers may be from, for example, post-consumer material but may alternatively be purge waste and / or scrap i.e., post-industrial or pre-consumer waste material. For the avoidance of doubt for the sake of this disclosure physically (mechanically) recycled / reclaimed particulates have their original crosslinked structure preserved, whereas chemically recycled materials do not. When the preformed silicone elastomeric particulates are physically recycled or reclaimed silicone elastomeric particulates, any suitable physical recycling method including mechanical reclaiming, thermo-mechanical reclaiming, cryomechanical reclaiming, and wet / solution grinding can be utilised to obtain the particulates. Examples of methods which may be utilised to generate the particulates include, for the sake of example, cryomilling (at liquid nitrogen temperatures), using milling equipment known in the art such as ball mills, pin mills, and the like, tornado milling (which can be done at either ambient or cryogenic temperatures in the solid state) and wet jet milling (e.g., wet jet) where the rubber is pulverized by an intense water stream. The preformed silicone elastomeric particulates have an average particle size of 1 mm or less. Smaller particle sizes are preferable to minimize stress-concentrating defects in the new article, but satisfactory performance has been achieved even for relatively large 1 mm sized milled preformed silicone elastomeric particulates. Particulates of an acceptable size may be obtained by mechanical screening through a sized mesh. Smaller particles are obtained by filtering through increasingly small meshes. The preformed silicone elastomeric particulates (e)(i) have an average unswollen particle size of 1 mm or less. Smaller average unswollen particle sizes are preferable to minimize stress- concentrating defects in the new article, but satisfactory performance has been achieved even for relatively large 1 mm sized milled silicone elastomer particulates. In one embodiment the average particle size of the preformed silicone elastomeric particulates was 600µm or less, alternatively the average particle size of the preformed silicone elastomeric particulates was 500µm or less, alternatively the average particle size of the preformed silicone elastomeric particulates was 400µm or less, alternatively the average particle size of the preformed silicone elastomeric particulates was 300µm or less, alternatively the average particle size of the preformed silicone elastomeric particulates was 200µm or less. Particulates of an acceptable size may be obtained by mechanical screening through a sized mesh. Smaller particles are obtained by filtering through increasingly small meshes. If the silicone elastomer to be made into preformed silicone elastomeric particulates (e)(i) is adhered to another material in prior use, they are preferably separated or delaminated. For example, in the case of wanting to recycle airbag articles the first step is to recover the silicone elastomer by delaminating same from the textile support. After which the resulting coating may be broken down into particulates using one of the processes listed above. However, it is to be understood that delamination or separation of silicone materials from certain substrates or articles may be imperfect and can lead to some residual minority fraction of adventitious non-silicone contaminants in the resulting particulates, such as small fragments of fabric or plastic substrates that may be present in quantities less than 10 wt. % of a particulate mixture, preferably 5 wt. % or less, with less being desirable. In one embodiment the aforementioned silicone elastomeric particulates are physically recycled and / or reclaimed silicone elastomeric particulates (e)(i). Physical recycling and / or reclamation using one or more of the different methods described above offers: 1) the advantage of being able to reuse of inorganic fillers, 2) the ability to incorporate contaminated feedstocks from deployed silicone elastomers, and the ability to tolerate residual Si-H from hydrosilylation cured silicone elastomers without needing to undergo the depolymerization, neutralization, filtration, and stripping steps associated with chemical recycling processes. In one example, cured silicone rubber samples were shredded with a paper shredder or cut with scissors until they were of a predetermined size e.g., less than 2cm particle size before being fed to a mill such as a MikroTMUMP-B mill commercially available from Hosokawa Micron Corporation. The shredded / cut rubber samples can be mixed with dry ice (which may be crushed into particulates using mortar and pestle) in an approximately 1:1 weight ratio in order to reduce the temperature of the rubber and help stiffen it for milling. The rubber / dry ice mixture can then be fed into a suitable mill using a knife blade rotor rotating at an rpm of > 10,000. The rubber can then be allowed to leave the milling chamber through a stainless-steel screen when the rubber is cut finer than the hole size of the screen, e.g., a 2-3 mm diameter round holes could be used for a first pass. The rubber milled in the first pass can then undergo a second pass with dry ice again as before and fed through the MikroTMUMP-B mill for a second pass this time using a 1mm slotted screen. If desired for more accurate particle size measurements samples can be measured using laser diffraction with e.g., a Beckman CoulterTMLS 13320 Particle Size Analyzer with the Tornado (dry) module commercially available from Beckman Coulter Inc., relying on the Beckman CoulterTMsoftware to deconvolute the diffraction signal to a particle size distribution determined using Fraunhofer diffraction model. Capping Agent (e)(iii) and Method In step (2) of the method described herein, the preformed silicone elastomeric particulates (e)(i) are chemically tuned by mixing the preformed silicone elastomeric particulates (e)(i) with a capping agent (e)(iii). The capping agent may, for example, be in the form of a compound having a single reactive chemical group (e)(iii) in order to passivate chemical groups on the particulate surface or in the particulate or in the form to introduce one or more chemically reactive groups on or in the particulates. The capping agent will undergo a chemical reaction with anticipated residual chemical groups in or on said preformed silicone elastomeric particulates (e)(i). Once mixed together, the preformed silicone elastomeric particulates (e)(i) and capping agent are left for a period of time to enable the reactive groups in or on the preformed silicone elastomeric particulates (e)(i) to chemically react with the capping agent (e)(iii). After this period of time chemically tuned preformed silicone elastomeric particulates (e)(i) are obtained. These may have for example been passivated to remove a large proportion if not all Si-H groups when the capping agent is a polymer or oligomer or the like having a single unsaturated group such as an alkenyl or alkynyl group which is being used to passivate the Si-H groups from hydrosilylation cured particulates. Alternatively, they may be used to passivate the number of alkoxy groups on condensation cured particulates or be used to introduced desired chemically reactive groups on to the particulates. The period of time used for the chemical tuning process, e.g., passivation or the like, can be of any preferred duration, for example from 6 hours to 72 hours, alternatively from 12 hours to 72 hours, alternatively from 24 hours to 72 hours in each case at room temperature and pressure. Preferably, addition of the capping agent (e)(iii) to the preformed silicone elastomeric particulates (e)(i) in step (2) occurs before and separately from steps (4) and (5). This appears to promote complete chemical tuning, e.g., passivation of the preformed silicone elastomeric particulates (e)(i). Preferably nearly stoichiometric amounts of the chemical groups in the capping agent (e)(iii) required to react with reactive groups in the preformed silicone elastomeric particulates (e)(i) are used. Otherwise, e.g., when the preformed silicone elastomeric particulates (e)(i) were hydrosilylation cured, potentially large excesses of unsaturated groups e.g., vinyl groups will be present and could potentially react into the curable silicone composition during cure which create defects that impact tensile properties. It is appreciated that the exact stoichiometry often cannot always be conveniently ascertained in the preformed silicone elastomeric particulates (e)(i) irrespective of their origin (and in some cases the nature of the cure chemistry also is not clear). If desired the preformed silicone elastomeric particulates (e)(i) and / or their source materials may be analysed to determine the chemical nature and method of curing prior to use and in this situation prior to chemical tuning. Any suitable analytical methods can be utilised. When the origin of the cured silicone rubber elastomeric particulates is unknown a priori, the cured rubber from which it originates or the physically recycled or reclaimed particulates can be characterized by a variety of known methods to ascertain the composition including spectroscopic techniques including infrared techniques such as Fourier transform infrared (FTIR) spectroscopy, attenuated total reflectance infrared spectroscopy (ATR- IR), infrared microscopy, Raman spectroscopy, Raman microscopy, solid state nuclear magnetic resonance (NMR) spectroscopy; chemical derivatization and titration techniques; chemical digestion followed by chromatography such as gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), liquid chromatography (LC), or by a variety of known elemental or ion analysis techniques such as inductively coupled plasma-optical emission spectroscopy (ICP-OES), x-ray fluorescence (XRF), and neutron activation analysis (NAA). However, even if there is an excess of the capping agent, its presence alone does not deter curing and in some cases can be beneficial to elastomeric properties such as elongation at break. The capping agent (e)(iii) preferably has a low number average molecular weight of less than < 40,000 g / mol, alternatively less than 30,000 alternatively less than 20,000 alternatively less than 10,000 alternatively less than 5,000 alternatively less than 1000 g / mol in each case determined by gel permeation chromatography. By having a low number average molecular weight, the capping agent (e)(iii) may also partially function as a means of swelling the preformed silicone elastomeric particulates (e)(i) as it is being chemically tuned. This dual role for the capping agent (e)(iii) will then reduce the swelling time required for step (4). Since stoichiometric amounts of capping agent (e)(iii) are being added relative the reactive groups in or on the preformed silicone elastomeric particulates optionally the capping agent (e)(iii) may be pre-mixed with a non-reactive swelling agent (such as trimethyl terminated polydimethylsiloxane having a zero-shear viscosity of less than 15,000mPa.s at 25oC. It was found that this may improve homogeneous dispersion of the capping agent (e)(iii). When chemical tuning of the preformed silicone elastomeric particulates (e)(i) is intended to passivate the particulates, the capping agent (e)(iii) is preferably a monofunctional capping agent (e)(iii) which might, for example, be a polydiorganosiloxane having one unsaturated group per molecule i.e., having one alkenyl or alkynyl group per molecule when the capping agent (e)(iii) is intended for passivating Si-H groups by capping the preformed silicone elastomeric particulates (e)(i). In one embodiment, the capping agent (e)(iii) might also function as the swelling agent by e.g., for example, in the case of passivating Si-H groups in or on the particulates, interacting with the residual Si-H groups while swelling the preformed silicone elastomeric particulates (e)(i). When seeking to cap preformed silicone elastomeric particulates (e)(i) containing -Si-H groups the capping agent (e)(iii) is typically a monoalkenyl-functional monomer or oligomer or a monoalkynyl- functional monomer or oligomer, for example a linear or branched alkene or alkyne comprising from 2 to 20 carbons, alternatively 6 to 15 carbons having one reactive alkene or alkyne group per molecule. An example being agent 1-dodecene (C10H21CH=CH2). Other compounds having a solitary alkene or alkyne group may alternatively be utilised providing the alkene or alkyne group is available for interaction with the Si-H of the hydrosilylation cured preformed silicone elastomeric particulates. For example, alkylvinyl ethers such as ethyl vinyl ether and dodecylvinyl ether, monovinyl polydimethylsiloxane, acrylates and methacrylates, such as methyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, iso-octyl acrylate, stearyl methacrylate, trimethoxysilylpropyl methacrylate, isobornyl methacrylate, and hexafluoroisopropyl methacrylate; polyalkylene glycols comprising one alkenyl or alkynyl group such as monovinyl polyethylene glycol, monovinyl polypropylene glycol and monovinyl polyethylenepolypropylene glycol copolymers; monoallyloxy polyalkylene glycols such as monoallyloxy polyethylene glycol and monoallyloxy polypropylene glycol and monoallyloxy polyethylenepolypropylene glycol copolymers; styrene, a-methyl styrene, acrylic acid, and hexafluoroisopropyl methacrylate. When the preformed silicone elastomeric particulates (e)(i) were condensation cured, then the particulates may be capped with compounds having at least one reactive group which will react with the reactive groups in the preformed silicone elastomeric particulates for example alkoxysilanes such as n-octyltrimethoxysilane, n-undecyltrimethoxysilane, methyltrimethoxysilane, isobutyltrimethoxysilane, n-propyldimethylmethoxysilane, n-butyltrimethoxysilane, ethyltrimethoxysilane, n-octylmethyldimethoxysilane and n-propylmethyldimethoxysilane; Alkenyl trialkoxysilanes such as vinyltrimethoxysilane, allyl trimethoxysilane, hexenyl trimethoxysilane, and undecylenyl trimethoxysilane; alkenyldialkoxyalkylsilanes such as vinyldimethoxymethylsilane, allyl dimethoxymethylsilane, hexenyl dimethoxymethylsilane and undecylenyl dimethoxymethylsilane, alkenylalkoxydialkylsilanes such as vinylmethoxydimethylsilane, allyl methoxydimethylsilane, hexenyl methoxydimethylsilane and undecylenyl methoxydimethylsilane; glycidoxyalkyltrialkoxysilanes such as glycidoxypropyltrimethoxysilane and glycidoxymethyltrimethoxysilane; glycidoxyalkyldialkoxyalkylsilanes such as glycidoxypropyldimethoxymethylsilane, glycidoxymethyldimethoxymethylsilane; and glycidoxyalkylalkoxydialkylsilanes such as glycidoxypropylmethoxydimethylsilane, glycidoxymethyl methoxydimethylsilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. These monofunctional capping agents (e)(iii) function as network modifying additives to “tune” the interface between the curable silicone composition and particulate phases and thus the chemically tuned particles when present in a cured material may affect tensile properties by promoting physical entanglement between said curable silicone composition and particulate phases. Preferably nearly stoichiometric amounts of the capping agent (e)(iii) relative to reactive groups in the preformed silicone elastomeric particulates (e)(i) (e.g., Si-H) are utilised when the chemical tuning is passivation. However, if appropriate potentially large excesses of unsaturated groups e.g., vinyl groups can be introduced if desired to provide a stronger interaction between the particulates and the surrounding material provided once the curable silicone composition is cured. It is appreciated that the exact stoichiometry often cannot always be conveniently ascertained in particulates and in some cases the nature of the cure chemistry also is not clear, but both may be assessed analytically prior to use if required. However, even if there is an excess of the capping agent (e)(iii), or if the capping agent (e)(iii) introduces an excess of reactive groups, its presence alone does not deter curing and in some cases can be beneficial to elastomeric properties such as elongation at break. Furthermore, the capping agent approach is most beneficial when both the cured silicone material and preformed silicone elastomeric particulates phases rely upon identical cure chemistries, as such systems are most susceptible to chemical reaction between the cured silicone material and preformed silicone elastomeric particulates (e)(i) phases. Hence the capping agents (e)(iii) act in the case of passivating hydrosilylation cured particulates as e.g., a means of capping Si-H groups to prevent the Si-H from chemical reaction with a hydrosilylation curing composition and this instead promotes physical entanglements in the fully cured article with the swelling agent (e)(ii) thereby minimizing the formation of localized regions of high crosslink density and thus improving elongation at break of the final silicone material after cure. To ensure homogeneous mixing of the capping agent (e)(iii) into the preformed silicone elastomeric particulates (e)(i), a non-reactive diluent (non-reactive swelling agent) can first be mixed with the capping agent (e)(iii) before mixing in the preformed silicone elastomeric particulates (e)(i). The non-reactive diluent functions as a vehicle to transport a small volume of capping agent (e)(iii) uniformly into the preformed silicone elastomeric particulates (e)(i). Under ambient conditions, residual catalyst in the preformed silicone elastomeric particulates (e)(i) (for example platinum family-based catalysts especially platinum based catalysts used for hydrosilylation cure processes) will catalyze the reaction between preformed silicone elastomeric particulates (e)(i) e.g., Si-H and vinyl groups in the capping agent (e)(iii). After 1 – 3 days under ambient conditions, the bulk of the residual reactive functionalities in the particulates are believed to have been chemically tuned by the capping agent (e)(iii), preventing chemical reaction between the matrix and preformed silicone elastomeric particulates (e)(i) in subsequent steps. It was found that the use of the capping step (2) for Si-H passivation offers the greatest improvement in tensile properties when the cured silicone material and preformed silicone elastomeric particulates (e)(i) Shore hardness are similar, as these systems are very sensitive to formation of highly crosslinked regions at the phase interface. Capping agent (e)(iii) is most critical when the preformed silicone elastomeric particulates (e)(i) and cured silicone material chemistries are complementarily reactive, e.g., Si-H on particulates with vinyl and Pt in curable silicone composition. In such cases, the preformed silicone elastomeric particulates (e)(i) and curable silicone composition can chemically react together which limit performance, as stress will be concentrated at the junctions between phases. More generally however, the capping step is advantageous as it allows the interface and stability of the preformed silicone elastomeric particulates to be tuned. In terms of stability, particulates will likely contain residual reactive functionality and trace amounts of catalyst which could cause pot life issues if the reactive functionalities are not chemically tuned. Penetration and Swelling of the mechanically recycled chemically tuned preformed silicone elastomeric particulates (e)(i) with an organopolysiloxane polymer swelling agent (e)(ii) having a zero-shear viscosity of less than or equal to (≤) 15,000 mPa.s at 25oC. Once the preformed silicone elastomeric particulates (e)(i) have been chemically tuned in the desired fashion by interaction with the capping (e)(iii) and undergoing a chemical reaction with the residual chemical groups in or on said preformed silicone elastomeric particulates (e)(i), such as Si- H groups in the case of preformed silicone elastomeric particulates made from hydrosilylation cured silicone rubber, they can be introduced into the curable silicone composition such as a hydrosilylation curable silicone composition. If a one-part composition is being used the chemically tuned preformed silicone elastomeric particulates (e)(i) can be added in directly. In the case of two- part compositions e.g., in the case of hydrosilylation curable silicone composition it may be easier to add the chemically tuned preformed silicone elastomeric particulates (e)(i) into one part of the composition, e.g., Part A or Part B. The fact that the preformed silicone elastomeric particulates (e)(i) have been chemically tuned means that either Part A or Part B may be used to contain them as the particulates / should not cause premature cure if added into the Part A composition containing the catalyst. Alternatively, it may be added to the Part B composition containing cross-linker but not catalyst. Organopolysiloxane polymer swelling agent (e)(ii) is present in the composition in an amount of from about 1.0 to 5.0wt. % of the composition. When the organopolysiloxane polymer swelling agent (e)(ii) is initially stored in one part of a two-part composition, e.g., in a Part B composition it may be present in an amount of from 2.wt. % to 10 wt. % of the Part B composition prior to mixing in a 1 : 1 weight ratio with Part A. Similarly, if component (e)(i) is pre-swollen in (e)(ii) an equivalent amount of component (e)(ii) may be utilised as when provided in the Part B composition. The preformed silicone elastomeric particulates (e)(i) are thoroughly mixed into the Part B composition (for example) in preparation for swelling should the Part B contain the reactive swelling agent. The above focused on hydrosilylation cured preformed silicone elastomeric particulates (e)(i) in an hydrosilylation curable silicone composition. However, it could also be extended to the capping of a condensation cured preformed silicone elastomeric particulates (e)(i) as well, using an alkyltrialkoxysilane in place of a mono-vinyl capping agent (e)(iii). This capped condensation cured preformed silicone elastomeric particulates (e)(i) can then be incorporated into a condensation curable silicone composition. As discussed above the preformed silicone elastomeric particulates (e)(i) in the curable silicone composition being prepared by the method herein have an average unswollen particle size of 1 mm or less. However, the chemically tuned preformed silicone elastomeric particulates (e)(i) are not just mixed directly into a standard curable silicone composition to be encapsulated therein as the composition cures. They are initially immersed and / or soaked in a low viscosity organopolysiloxane polymer having a zero-shear viscosity of less than or equal (≤) to 15,000 mPa.s at 25oC (e)(ii), alternatively a zero-shear viscosity of from 100 to 13,000 mPa.s at 25oC (e)(ii), alternatively a zero-shear viscosity of from 100 to 10,000 mPa.s at 25oC (e)(ii), alternatively a zero- shear viscosity of from 100 to 7,500 mPa.s at 25oC (e)(ii), alternatively a zero-shear viscosity of from 100 to 5,000 mPa.s at 25oC (e)(ii), alternatively a zero-shear viscosity of from 100 to 2,000 mPa.s at 25oC (e)(ii). Examples of (e)(ii) include vinyl dimethyl terminated Divinyl-functional polydimethylsiloxanes, hydroxyl terminated polydiorganosiloxanes, alkoxy terminated polydiorganosiloxanes or siloxane cross-linkers as defined as component (c) herein such as a polymethylhydrogen dimethylsiloxane copolymers. They may also be unreactive silicone plasticizers such as trimethyl terminated polydimethylsiloxanes. The organopolysiloxane polymer swelling agent (e)(ii) is present in the curable silicone composition in an amount of from about 1.0 to 5.0wt. % of the composition. The chemically tuned preformed silicone elastomeric particulates (e)(i) may or may not be reactive with the organopolysiloxane polymer having a zero-shear viscosity of ≤ 15,000 mPa.s at 25oC (e)(ii), equally it may or may not be reactive with components of the curable silicone composition in which it is to be situated. It was found that the inclusion of a pre-cured phase of preformed silicone elastomeric particulates (e)(i) within a second curable network with an organopolysiloxane polymer having a zero-shear viscosity of ≤ 15,000 mPa.s at 25oC (e)(ii) capable of penetrating and swelling preformed silicone elastomeric particulates (e)(i) provides a means of forming double networks or inter-penetrating networks (IPNs). Without being bound to currently held theories it is believed that particulates component (e)(i) consists of a pre-cured cross-linked “mesh” component and composition of which component (e)(ii) forms a part also forms a cross-linked network and because of the ability for component (e)(ii) to penetrate and swell chemically tuned component (e)(i), the two networks physically entangle so that there is physical engagement rather than mere encapsulation. It was found that the lower the viscosity value of component (e)(ii) the greater the penetration and swelling of component (e)(i) occurred. Furthermore, penetration and swelling did not occur or occurred minimally when the component (e)(ii) had a zero-shear viscosity of greater 15,000 mPa.s at 25oC. Components (e)(i) and (e)(ii) were compatible, so there appeared to be no problems with component (e)(ii) penetrating into and swelling component (e)(i) providing the zero-shear viscosity of component (e)(ii) was within the range stated. However, given the chemically tuned preformed silicone elastomeric particulates (e)(i) are thermoset materials and due to their crosslinked nature unable to dissolve in component (e)(ii). So, it instead swells to accommodate the organopolysiloxane polymer of component (e)(ii). The chemically tuned preformed silicone elastomeric particulates (e)(i) are thus physically well bound in the matrix and cannot serve as defects in the matrix, creating voids, surface protrusions or other heterogeneities in the matrix which are often a problem when merely encapsulated and used as a filler. In a first embodiment the chemically tuned preformed silicone elastomeric particulates (e)(i) may be penetrated and soaked organopolysiloxane polymer swelling agent (e)(ii) having a zero-shear viscosity of less than or equal to (≤) 15,000 mPa.s at 25oC for a suitable period of time. In this embodiment the organopolysiloxane polymer swelling agent (e)(ii) is preferably neat or unadulterated. The suitable period of time may be at least 1 hour, alternatively at least 12 hours, alternatively at least 24 hours, alternatively at least 48 hours. This enables said organopolysiloxane polymer swelling agent (e)(ii) to penetrate and swell said chemically tuned preformed silicone elastomeric particulates (e)(i) to form component (e). This equates to step (4) of the method above. Subsequently the resulting mixture of swollen (e)(i) and residual (e)(ii) are added to the curable silicone composition or a part thereof, typically the Part B composition which comprises step (5) in the above method. As indicated previously, in another embodiment steps (4), (5) and optionally (6) may be carried out simultaneously in a single step and furthermore, alternatively steps (2), (4), (5) and (6) may be carried out simultaneously in a single step. In this embodiment component (e) may be prepared by swelling the chemically tuned preformed silicone elastomeric particulates (e)(i) in the curable silicone composition containing component (e)(ii) or more often in a part composition of the curable silicone composition when being stored in multiple parts prior to use. In such an embodiment swelling can occur throughout the period during which particulates (e)(i) are stored in the presence of component (e)(ii) in said part of the curable silicone composition containing component (e)(ii). When the organopolysiloxane polymer swelling agent (e)(ii) is initially stored in one part of a two- part composition, e.g., in a Part B composition it may be present in an amount of from 2.wt. % to 10 wt. % of the part B composition prior to mixing in a 1 : 1 weight ratio with Part A. Typically, the part B composition is used as it does not contain any catalyst the particulates may contain Si-H groups which could initiate some curing during storage if mixed with the catalyst. In this embodiment organopolysiloxane polymer swelling agent (e)(ii) may comprise or consist of component (c) the cross-linker or at least 1.0 wt. % of component (a) or a mixture of both component (c) and said at least 1.0 wt. % of component (a) or may be an organopolysiloxane polymer plasticiser. the particulates (e)(i) are swelled after being added to the relevant part of the composition containing component (e)(ii). For example, the swelling agent may be introduced into the Part B composition (described in more detail later) and the preformed silicone elastomeric particulates (e)(i) are swollen for a predetermined period of time in the Part B composition, after which the parts A and B compositions are mixed together and the curable silicone composition is cured. Typically, preformed silicone elastomeric particulates (e)(i) will remain swollen by the presence of organopolysiloxane polymer swelling agent (e)(ii) throughout the lifetime of its use, even after cure. Chemically tuned and Swelled component (e) Typically said component (e), after component (e)(i) has been chemically tuned by capping agent (e)(iii) and swelled by component (e)(ii) for a predetermined time, is present in an amount of from 5 wt. % to 80 wt. % of the composition, alternatively is present in an amount of from 5 wt. % to 50 wt. % of the composition, n, alternatively in an amount of from 7.5 wt. % to 35 wt. % of the composition, alternatively in an amount of from 7.5 wt. % to 30 wt. % of the composition, alternatively in an amount of from 9.0 wt. % to 25 wt. % of the composition. Curable Silicone Composition The curable silicone composition may be any suitable curable silicone composition into which the chemically tuned and optionally pre-swelled preformed silicone elastomeric particulates (e)(i) can be introduced in the method disclosed. Alternatively, the curable silicone composition is selected from a hydrosilylation curable silicone composition, a peroxide cure silicone composition or a condensation curable (RTV) silicone composition. Hydrosilylation Curable Silicone Composition When the curable silicone composition is a hydrosilylation curable silicone composition, in addition to components (e)(i), (e)(ii) and (e)(iii) the hydrosilylation curable silicone rubber composition comprises the following components: Component (a) of the hydrosilylation curable silicone composition Component (a) of the hydrosilylation curable silicone rubber composition is one or more organopolysiloxane polymers having a viscosity of between 100 and 200,000mPa.s inclusive at 25 ºC, and at least two unsaturated groups per molecule, which unsaturated groups are selected from alkenyl or alkynyl groups. Each organopolysiloxane polymer of component (a) comprises multiple siloxy units, of formula (I): R’aSiO(4-a) / 2(I) The subscript “a” is 0, 1, 2 or 3. Siloxy units may be described by a shorthand (abbreviated) nomenclature, namely - "M," "D," "T," and "Q", when R’ is as described above, alternatively an alkyl group, typically a methyl group. The M unit corresponds to a siloxy unit where a = 3, that is R’3SiO1 / 2; the D unit corresponds to a siloxy unit where a = 2, namely R’2SiO2 / 2; the T unit corresponds to a siloxy unit where a = 1, namely R’1SiO3 / 2; the Q unit corresponds to a siloxy unit where a = 0, namely SiO4 / 2. The organopolysiloxane polymer of component (a) is substantially linear but may contain a proportion of branching due to the presence of T units (as previously described) within the molecule, hence the average value of a in structure (I) is about 2. The unsaturated groups of component (a) of the hydrosilylation curable silicone rubber composition may be positioned either terminally or pendently on the organopolysiloxane polymer, or in both locations. The unsaturated groups of component (a) may be alkenyl groups or alkynyl groups as described above. Each alkenyl group, when present, may comprise for example from 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms. When present the alkenyl groups may be exemplified by, but not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl and cyclohexenyl groups. Each alkynyl group, when present, may also have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms. Examples of alkynyl groups may be exemplified by, but not limited to, ethynyl, propynyl, and butynyl groups. Preferred examples of the unsaturated groups of component (a) include vinyl, propenyl, isopropenyl, butenyl, allyl, and 5- hexenyl. In formula (I), each R’, other than the unsaturated groups described above, is independently selected from an aliphatic hydrocarbyl group, a substituted aliphatic hydrocarbyl group, an aromatic group or a substituted aromatic group. Each aliphatic hydrocarbyl group may be exemplified by, but not limited to, alkyl groups having from 1 to 20 carbons per group, alternatively 1 to 15 carbons per group, alternatively 1 to 12 carbons per group, alternatively 1 to 10 carbons per group, alternatively 1 to 6 carbons per group or cycloalkyl groups such as cyclohexyl. Specific examples of alkyl groups may include methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl groups, alternatively methyl and ethyl groups. Substituted aliphatic hydrocarbyl group are preferably non-halogenated substituted alkyl groups. The aliphatic non-halogenated organyl groups are exemplified by, but not limited to alkyl groups as described above with a substituted group such as suitable nitrogen containing groups such as amido groups, imido groups; oxygen containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups and hydroxyl groups. Further organyl groups may include sulfur containing groups, phosphorus containing groups, boron containing groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups with substituted groups as described above. Component (a) of the hydrosilylation curable silicone rubber composition may, for example, be selected from polydimethylsiloxanes, alkylmethylpolysiloxanes, alkylarylpolysiloxanes or copolymers thereof (where reference to alkyl means any suitable alkyl group, alternatively an alkyl group having two or more carbons) providing each polymer has a viscosity of between 100 and 200,000mPa.s inclusive at 25 ºC, Hence component (a) of the hydrosilylation curable silicone rubber composition may, for the sake of example, be: a dialkylalkenyl terminated polydimethylsiloxane, e.g., dimethylvinyl terminated polydimethylsiloxane; a dialkylalkenyl terminated dimethylmethylphenylsiloxane, e.g., dimethylvinyl terminated dimethylmethylphenylsiloxane; a trialkyl terminated dimethylmethylvinyl polysiloxane; a dialkylvinyl terminated dimethylmethylvinyl polysiloxane copolymer; a dialkylvinyl terminated methylphenylpolysiloxane, a dialkylalkenyl terminated methylvinylmethylphenylsiloxane; a dialkylalkenyl terminated methylvinyldiphenylsiloxane; a dialkylalkenyl terminated methylvinyl methylphenyl dimethylsiloxane; a trimethyl terminated methylvinyl methylphenylsiloxane; a trimethyl terminated methylvinyl diphenylsiloxane; or a trimethyl terminated methylvinyl methylphenyl dimethylsiloxane. In each case, component (a) of the hydrosilylation curable silicone rubber composition has a viscosity from 100 to 200,000mPa.s inclusive at 25 ºC, alternatively from 1000 to 150,000mPa.s at 25 ºC, alternatively, from 1000mPa.s to 125,000mPa.s, alternatively from 1000mPa.s to 100,000mPa.s at 25 ºC. Unless otherwise indicated all viscosity measurement given are zero-shear viscosity (ηo) values, obtained by extrapolating to zero the value taken at low shear rates (or simply taking an average of values) in the limit where the viscosity-shear rate curve is rate-independent, which is a test-method independent value provided a suitable, properly operating rheometer is used. For example, the zero- shear viscosity of a substance at 25 °C may be obtained by using commercial rheometers such as an Anton-Parr MCR-301 rheometer or a TA Instruments AR-2000 rheometer equipped with cone-and- plate fixtures of suitable diameter to generate adequate torque signal at a series of low shear rates, such as 0.01 s-1, 0.1 s-1and 1.0 s-1while not exceeding the torque limits of the transducer. Alternatively, the viscosity measurements may be obtained using an ARES-G2 rotational rheometer, commercially available from TA Instruments using a steady rate sweep from 0.1 to 10 s-1on a 25 mm cone and plate. If the zero-shear plateau region cannot be observed at shear rates accessible to the rheometer or viscometer, we report the viscosity measured at a standard shear rate of 0.1 s-1at 25 °C. Typically, the alkenyl and / or alkynyl content, e.g., vinyl content of the polymer is from 0.01 to 3 wt. % for each organopolysiloxane polymer containing at least two silicon-bonded alkenyl groups per molecule of component (a), alternatively from 0.01 to 2.5 wt. % of component (a), alternatively from 0.001 to 2.0 wt. %, alternatively from 0.01 to 1.5 wt. % of component (a) of the or each organopolysiloxane polymer containing at least two unsaturated groups per molecule, which unsaturated groups are selected from alkenyl or alkynyl groups per molecule of component (a). The alkenyl / alkynyl content of component (a) is determined using quantitative infra-red analysis in accordance with ASTM E168. Component (a) may be present in the hydrosilylation curable silicone rubber composition in an amount of from 40 wt. % to about 80 wt. % of the hydrosilylation curable silicone rubber composition, alternatively from 45 to 80 wt. % of the composition, alternatively from 50 to 80 wt. % of the hydrosilylation curable silicone rubber composition. Typically, component (a) is present in an amount which is the difference between 100 wt. % and the cumulative wt. % of the other components / ingredients of the composition. Component (b) of the hydrosilylation curable silicone rubber composition Component (b) of the hydrosilylation curable silicone rubber composition is a reinforcing filler comprising fumed silica, precipitated silica or a mixture thereof. Finely divided forms of silica are preferred. The reinforcing filler is provided to reinforce the physical properties of the elastomers provided when the composition is cured. Reinforcing fillers (b) e.g., silica fillers having a relatively high surface area, typically at least 50 m² / g (BET method in accordance with ISO 9277: 2010) are utilized. For example, fillers, (e.g., fumed silica) having surface areas of from 50-450m2 / g, alternatively, 50 – 400m2 / g m2 / g, alternatively from 50 to 300 m² / g, alternatively 100 - 300m2 / g (BET method in accordance with ISO 9277: 2010) are typically used. Typically, the reinforcing filler(s) (b) of the hydrosilylation curable silicone rubber composition is / are naturally hydrophilic (e.g., untreated) silica fillers, and are therefore treated with a treating agent to render it / them hydrophobic. These surface modified reinforcing fillers (b) do not clump and can be homogeneously incorporated into organopolysiloxane polymer (a), described below, as the surface treatment makes the fillers easily wetted by organopolysiloxane polymer (a). Typically, the reinforcing filler (b) of the hydrosilylation curable silicone rubber composition may be surface treated with any low molecular weight organosilicon compounds disclosed in the art applicable to prevent creping of organosiloxane compositions during processing. For example, organosilanes, polydiorganosiloxanes, or organosilazanes e.g., hexaalkyl disilazane, short chain siloxane diols or fatty acids or fatty acid esters such as stearates may be used to render the filler(s) hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other ingredients. Specific examples include but are not restricted to silanol terminated trifluoropropylmethyl siloxane, silanol terminated vinylmethylsiloxane, tetramethyldi(trifluoropropyl)disilazane, tetramethyldivinyl disilazane, hexamethyl disilazane (HMDZ), silanol terminated MePh siloxane, liquid hydroxyl-terminated polydiorganosiloxane containing an average from 2 to 20 repeating units of diorganosiloxane in each molecule, hexaorganodisiloxane, hexaorganodisilazane. A small amount of water can be added together with the silica treating agent(s) as a processing aid. The reinforcing silica fillers (b) may be pre-treated prior to introduction into the hydrosilylation curable silicone rubber composition or may be treated in situ (i.e., in the presence of at least a portion of the other ingredients of the hydrosilylation curable silicone rubber composition herein by blending these ingredients together at room temperature or above until the filler is completely treated. Typically, when present untreated reinforcing filler (b) is treated in situ with a treating agent in the presence of organopolysiloxane polymer (a) which results in the preparation of a silicone rubber base material which can subsequently be mixed with other ingredients. The reinforcing filler (b) is present in the hydrosilylation curable silicone rubber composition in an amount of from 1.0 to 40wt. %. of the composition, alternatively of from 1 to 30wt. %. of the composition, alternatively of from 5.0 to 25wt. %. of the composition. Component (c) of the hydrosilylation curable silicone rubber composition Component (c) of the hydrosilylation curable silicone rubber composition functions as a cross-linker and is provided in the form of an organosilicon compound having an average of at least two, alternatively at least three Si-H groups per molecule. Component (c) normally contains three or more silicon-bonded hydrogen atoms so that the hydrogen atoms can react with the unsaturated groups (alkenyl and / or alkynyl groups) of component (a) and / or the rest of the composition to form a network structure therewith and thereby cure the composition. Some or all of Component (c) may alternatively have two silicon bonded hydrogen atoms per molecule. However, such a molecule is only used as the sole cross-linker when e.g., polymer (a) has greater than two unsaturated groups per molecule in which case a network can be produced during the cure process. Otherwise, when component (c) partially comprises molecules having an average of two silicon bonded hydrogen atoms per molecule, said molecules may function as a chain extender. The molecular configuration of the organosilicon compound having an average of at least two, alternatively at least three Si-H groups per molecule (c) is not specifically restricted, and it can be a silane or a straight chain, branched (a straight chain with some branching through the presence of T units) or cyclic polymer or be silicone resin based. All viscosities are measured at 25oC and are zero-shear measurements using the method described previously. Silicon-bonded organic groups used in component (c) may be exemplified by alkyl groups such as methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl; aryl groups such as phenyl tolyl, xylyl, or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl, or similar halogenated alkyl group, preferred alkyl groups having from 1 to 6 carbons, especially methyl ethyl or propyl groups or phenyl groups. Preferably the silicon-bonded organic groups used in component (c) are alkyl groups, alternatively methyl, ethyl or propyl groups. Examples of the organosilicon compound having an average of at least two, alternatively at least three Si-H groups per molecule (c) include but are not limited to: (a1) trimethylsiloxy-terminated methylhydrogenpolysiloxane, (b1) trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane, (c1) dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymers, (d1) dimethylsiloxane-methylhydrogensiloxane cyclic copolymers, (e1) copolymers and / or silicon resins consisting of (CH3)2HSiO1 / 2 units, (CH3)3SiO1 / 2 units and SiO4 / 2 units, (f1) copolymers and / or silicone resins consisting of (CH3)2HSiO1 / 2 units and SiO4 / 2 units, (g1) Methylhydrogensiloxane cyclic homopolymers having between 3 and 10 silicon atoms per molecule; alternatively, component (c), the cross-linker, may be a filler, e.g., silica treated with one of the above, and mixtures thereof. In one embodiment the component (c) is selected from a methylhydrogenpolysiloxane capped at both molecular terminals with trimethylsiloxy groups; a copolymer of a methylhydrogensiloxane and a dimethylsiloxane capped at both molecular terminals with trimethylsiloxy groups; dimethylsiloxane capped at both molecular terminals with dimethylhydrogensiloxy groups; a copolymer of a methylhydrogensiloxane and a dimethylsiloxane capped at both molecular terminals with dimethylhydrogensiloxy groups. The cross-linker (c) is generally present in the hydrosilylation curable silicone rubber composition such that the molar ratio of the silicon-bonded hydrogen atoms in component (c) to the total unsaturated groups selected from alkenyl and / or alkynyl groups in the composition is from 0.5:1 to 20:1. When this ratio is less than 0.5:1, a well-cured composition will not be obtained. When the ratio exceeds 20:1, there is a tendency for the hardness of the cured hydrosilylation curable silicone rubber composition to increase when heated. The molar ratio of silicon-bonded hydrogen atoms of component (c) to total unsaturated groups selected from alkenyl and / or alkynyl groups in the organopolysiloxane (a) is in some embodiments at least 0.8:1 but is preferably at least 1:1 and can be up to 8:1 or 10:1. Most preferably the molar ratio of Si-H groups to aliphatically unsaturated groups is in the range from 1.1:1 to 5:1. The silicon-bonded hydrogen (Si-H) content of component (c) is determined using quantitative infra-red analysis in accordance with ASTM E168. In the present instance the silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl ratio is important when relying on a hydrosilylation cure process. Generally, this is determined by calculating the total weight % of alkenyl groups in the hydrosilylation curable silicone rubber composition e.g., vinyl [V] and the total weight % of silicon bonded hydrogen [H] in the composition and given the molecular weight of hydrogen is 1 and of vinyl is 27 the molar ratio of silicon bonded hydrogen to vinyl is 27[H] / [V]. Typically, dependent on the number of unsaturated groups in component (a) and the rest of the hydrosilylation curable silicone rubber composition as well as the number of Si-H groups in component (c), component (c) will be present in an amount of from 0.1 to 10 wt. % of the hydrosilylation curable silicone rubber composition, alternatively 0.1 to 7.5 wt. % of the hydrosilylation curable silicone rubber composition, alternatively 0.25 to 7.5wt. %, further alternatively from 0.25% to 5 wt. % of the hydrosilylation curable silicone rubber composition. Component (d) of the hydrosilylation curable silicone rubber composition Component (d) of the hydrosilylation curable silicone rubber composition, is a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof. These are usually selected from catalysts of the platinum group of metals (platinum, ruthenium, osmium, rhodium, iridium and palladium), or a compound of one or more of such metals. Alternatively, platinum and rhodium compounds are preferred due to the high activity level of these catalysts in hydrosilylation reactions, with platinum compounds most preferred. In a hydrosilylation (or addition) reaction, a hydrosilylation catalyst such as component (d) herein catalyses the reaction between an unsaturated group, usually an alkenyl group e.g., vinyl with Si-H groups. The hydrosilylation catalyst of component (d) can be a platinum group metal, a platinum group metal deposited on a carrier, such as activated carbon, metal oxides, such as silicon dioxide, silica gel or powdered charcoal, or a compound or complex of a platinum group metal. Preferably the platinum group metal is platinum. Examples of preferred hydrosilylation catalysts of component (d) of the hydrosilylation curable silicone rubber composition are platinum based catalysts, for example, platinum black, platinum oxide (Adams catalyst), platinum on various solid supports, chloroplatinic acids, e.g., hexachloroplatinic acid (Pt oxidation state IV) (Speier catalyst), chloroplatinic acid in solutions of alcohols e.g., isooctanol or amyl alcohol (Lamoreaux catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups, e.g., tetra-vinyl-tetramethylcyclotetrasiloxane-platinum complex (Ashby catalyst). Soluble platinum compounds that can be used include, for example, the platinum-olefin complexes of the formulae (PtCl2.(olefin)2 and H(PtCl3.olefin), preference being given in this context to the use of alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, isomers of butene and of octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene. Other soluble platinum catalysts are, for the sake of example a platinum-cyclopropane complex of the formula (PtCl2C3H6)2, the reaction products of hexachloroplatinic acid with alcohols, ethers, and aldehydes or mixtures thereof, or the reaction product of hexachloroplatinic acid and / or its conversion products with vinyl-containing siloxanes such as methylvinylcyclotetrasiloxane in the presence of sodium bicarbonate in ethanolic solution. Platinum catalysts with phosphorus, sulfur, and amine ligands can be used as well, e.g., (Ph3P)2PtCl2; and complexes of platinum with vinylsiloxanes, such as sym- divinyltetramethyldisiloxane (Karstedt’s catalyst). Hence, specific examples of suitable platinum-based catalysts of component (d) of the hydrosilylation curable silicone rubber composition include: (i) complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups are described in US 3,419,593; (ii) chloroplatinic acid, either in hexahydrate form or anhydrous form; (iii) a platinum-containing catalyst which is obtained by a method comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound, such as divinyltetramethyldisiloxane; (iv) alkene-platinum-silyl complexes as described in US Pat. No.6,605,734 such as (COD)Pt(SiMeCl2)2 where “COD” is 1,5-cyclooctadiene; and / or (v) Karstedt's catalyst, a platinum divinyl tetramethyl disiloxane complex typically containing about 1 wt. % of platinum typically in a vinyl siloxane polymer. Solvents such as toluene and the like organic solvents have been used historically as alternatives but the use of vinyl siloxane polymers by far the preferred choice. These are described in US3,715,334 and US3,814,730. In one preferred embodiment component (d) may be selected from co-ordination compounds of platinum. In one embodiment hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt's catalysts and Speier catalysts are preferred. In one embodiment the catalyst may be encapsulated during storage, especially in the case of one-part compositions to prevent premature cure. The catalytic amount of the hydrosilylation catalyst is generally between 0.01 ppm, and 10,000 parts by weight of platinum-group metal, per million parts (ppm), based on the weight of the hydrosilylation curable silicone rubber composition; alternatively, between 0.1 and 7500ppm; alternatively, between 100 and 75000 ppm, and alternatively between 500 and 6,000 ppm. The ranges may relate solely to the metal content within the catalyst or to the catalyst altogether (including its ligands) as specified, but typically these ranges relate solely to the metal content within the catalyst. The catalyst may be added as a single species or as a mixture of two or more different species. Typically, dependent on the form / concentration in which the catalyst is provided e.g., in a polymer or solvent, the amount of component (d) present will be within the range of from 0.001 to 3.0 wt. % of the hydrosilylation curable silicone rubber composition, alternatively from 0.001 to 1.5 wt. % of the composition, alternatively from 0.01–1.5 wt. %, alternatively 0.01 to 0.1.0 wt. %, of the hydrosilylation curable silicone rubber composition. Additional optional ingredients of the hydrosilylation curable silicone rubber composition Additional optional ingredients may be present in the hydrosilylation curable silicone rubber composition as hereinbefore described depending on the intended final use thereof. Examples of such optional ingredients include cure inhibitors, pot life extenders, flame retardants, lubricants, non-reinforcing fillers (as described below in respect to condensation compositions), adhesion promoters, pigments and / or colouring agents, bactericides, wetting agents, heat stabilizers, compression set additives, plasticizers (as described below in respect to condensation compositions), silicone resins and mixtures thereof. When the hydrosilylation curable silicone rubber composition as hereinbefore described is being cured via an addition / hydrosilylation reaction a cure inhibitor may be utilized to inhibit the cure of the composition. These cure inhibitors are utilized to prevent premature cure in storage and / or to obtain a longer working time or pot life of a hydrosilylation cured composition by retarding or suppressing the activity of the catalyst. Inhibitors of hydrosilylation catalysts (d), e.g., platinum metal-based catalysts are well known in the art and may include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, such as dibutyl maleate; fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, such as tetramethyltetravinylcyclotetrasiloxane; unsaturated hydrocarbon monoesters and diesters, conjugated ene-ynes, hydroperoxides, nitriles, and diaziridines. Alkenyl- substituted siloxanes as described in US 3,989,667 may be used, of which cyclic methylvinylsiloxanes are preferred. One class of known cure inhibitors of hydrosilylation catalysts, e.g., platinum catalysts (d) include the acetylenic compounds disclosed in US 3,445,420. Acetylenic alcohols such as 2-methyl-3-butyn-2-ol constitute a preferred class of cure inhibitors that will suppress the activity of a platinum-containing catalyst at 25 ºC. Compositions containing these cure inhibitors typically require heating at temperature of 70 ºC or above to cure at a practical rate. Examples of acetylenic alcohols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2- methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-methyl butynol 3-butyn-2-ol, propargyl alcohol, 2-phenyl-2- propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1- penten-4-yn-3-ol, and mixtures thereof. In one alternative the cure inhibitor is selected from one or more of 1-ethynyl-1-cyclohexanol (ETCH), tetramethyltetravinylcyclotetrasiloxane, 3-methyl butynol and / or dibutyl maleate. When present, cure inhibitor concentrations as low as 1 mole of cure inhibitor per mole of the metal of catalyst (d) will in some instances impart satisfactory storage stability and cure rate. In other instances, cure inhibitor concentrations of up to 500 moles of cure inhibitor per mole of the metal of catalyst (d) are required. The optimum concentration for a given cure inhibitor in a given hydrosilylation curable silicone rubber composition herein is readily determined by routine experimentation. Mixtures of the above may also be used. Dependent on the concentration and form in which the cure inhibitor selected is provided / available commercially, when present in the composition, the cure inhibitor is typically present in an amount of from 0.0001-10wt. %, alternatively 0.001-5%, cure inhibitor, alternatively 0.0125 to 5wt. % of the composition. Pot life extenders, such as triazole, may be used, but are not considered necessary in the scope of the present invention. The hydrosilylation curable silicone rubber composition may thus be free of pot life extender. Adhesion Promoter A curable silicone composition as described herein, may optionally contain a suitable adhesion promoter. When present, any suitable adhesion promoter may be utilised if desired. The adhesion promoter may for example be an alkoxysilane coupling agent, Examples of adhesion promoters which may be incorporated in curable compositions according to the invention include alkoxysilanes such as aminoalkylalkoxysilanes, for example 3-aminopropyltriethoxysilane, epoxyalkylalkoxysilanes, for example, 3-glycidoxypropyltrimethoxysilane and, mercapto- alkylalkoxysilanes, and reaction products of ethylenediamine with silylacrylates. Isocyanurates containing silicon groups such as 1, 3, 5-tris(trialkoxysilylalkyl) isocyanurates may additionally be used. Further suitable adhesion promoters are reaction products of epoxyalkylalkoxysilanes such as 3-glycidoxypropyltrimethoxysilane with amino-substituted alkoxysilanes such as 3- aminopropyltrimethoxysilane and optionally with alkylalkoxysilanes such as methyltrimethoxysilane. When present, the adhesion promoter may be present in an amount of from 0.1 to 5.0 wt. % of the composition, alternatively from 0.1 to 3.5 wt. % of the composition alternatively from 0.1 to 2.5 wt. % of the composition, alternatively from 0.1 to 2.25 wt. % of the composition alternatively from 0.2 to 2.0 wt. % of the composition. Further suitable adhesion promoters are reaction products of epoxyalkylalkoxysilanes such as 3- glycidoxypropyltrimethoxysilane with amino-substituted alkoxysilanes such as 3- aminopropyltrimethoxysilane and optionally with alkylalkoxysilanes such as methyltrimethoxysilane. In one alternative the adhesion promoter may be a combination of an alkoxysilane coupling agent with an organometallic adhesion catalyst such as zirconium (IV) tetraacetyl acetonate, (sometimes referred to as zirconium AcAc4), or aluminium (III) triacetyl acetonate, (sometimes referred to as aluminium AcAc3). Typically, when present such a catalyst is introduced in an amount of from 0.05 - 0.3 wt.% of the composition. Typically, prior to use the hydrosilylation curable silicone rubber composition utilised to make the silicone rubber elastomeric materials herein is stored in two parts, Part A and Part B to keep components (c) cross-linker and (d) hydrosilylation cure catalyst apart to avoid premature cure. Typically, a Part A composition will comprise components (a) polymer, (b) reinforcing filler and (d) hydrosilylation cure catalyst and Part B will comprise components (a), reinforcing filler (b), cross- linker (c), and optional cure inhibitor, when present. Given the preformed silicone elastomeric particulates (e)(i) have been chemically tuned by (e)(iii), they may be introduced into the Part A the Part B or both Part A and Part B composition after having been chemically tuned by (e)(iii) and optionally pre-swollen by (e)(ii). In the situation when the preformed silicone elastomeric particulates were made from a hydrosilylation cured source material, the removal of the Si-H groups by the chemically tuning step (2), in this case a passivation step (2) means the Part A composition containing a catalyst should not pre-cure during storage in the presence of the chemically tuned preformed silicone elastomeric particulates (e)(i). Alternatively, the chemically tuned preformed silicone elastomeric particulates (e)(i) may undergo the swelling step (4) in the Part A composition the Part B composition or both the Part A and Part B compositions. In such a case the swelling agent (e)(ii) being utilised is mixed into the Part selected typically before the addition of the chemically tuned preformed silicone elastomeric particulates (e)(i). In one alternative, when some of component (a) has a sufficiently low viscosity (i.e., less than 15,000mPa.s) said component (a) may be utilised to function as component (e)(ii), in which case the preformed silicone elastomeric particulates (e)(i) can be added directly into the selected Part composition and be allowed to swell for a period of time. When the preformed silicone elastomeric particulates (e)(i) and component (e)(ii) are mixed together in a pre-mix, the pre-mix of component (e) may, once said period of time allowed for swelling the preformed silicone elastomeric particulates (e)(i) has expired, be added directly into the selected Part or may be kept separately in a Part C composition alone or with additional component (a). The Part C is then mixed into the final composition when Parts A and B are mixed together. Other optional additives (i.e., other than cure inhibitor) when present in a hydrosilylation curable silicone rubber composition may be in either Part A or Part B, providing they do not negatively affect the properties of any other components present (e.g., catalyst inactivation). Part A and Part B of the hydrosilylation curable silicone rubber composition described herein are mixed together shortly prior to use to initiate cure of the full composition into a silicone elastomeric material. The Part A and Part B compositions (and optional Part C containing component (e)) can be designed to be mixed in any suitable weight ratio e.g., Part A : Part B may be mixed together in weight ratios of from 10:1 to 1:10, alternatively from 5:1 to 1:5, alternatively from 2:1 to 1:2, but most preferred is a weight ratio of 1:1. The ingredients of the Part A composition and the ingredients of the Part B may be respectively mixed together in any suitable manner with components being introduced individually or may be introduced into the composition in pre-prepared combinations for, e.g., ease of mixing the final composition. For Example, components (a) and (b) are often mixed together to form a polymer base or masterbatch with silica optionally being treated in situ, prior to addition with other ingredients. Similarly, component (e) may also be premixed with component (a), if desired. These may then be mixed with the other ingredients of Part B made directly or may be used to make pre-prepared concentrates commonly referred to in the industry as masterbatches. Any mixing techniques and devices described in the prior art can be used for making the Part A and Part B compositions. The particular device to be used will be determined by the viscosities of components and the final composition. Suitable mixers include but are not limited to paddle type mixers e.g., planetary mixers and kneader type mixers. Cooling of components during mixing may be desirable to avoid premature curing of the composition. The hydrosilylation curable silicone rubber composition as hereinbefore described may be placed in a mold or applied onto a substrate or the like prior to cure by any suitable known technique. Curing of the hydrosilylation curable silicone rubber composition can take place in a mold to form a molded part, by injection molding, using e.g., a liquid injection molding system (LIMS) press moulding, extrusion moulding, transfer moulding, press vulcanization, or calendaring. The hydrosilylation curable silicone rubber composition is cured at any suitable temperature e.g., at a temperature of from 80oC to 200oC, alternatively from about 100oC to 180oC, alternatively from about 120oC to 180oC. Peroxide curable silicone composition When the curable silicone composition is a peroxide curable silicone rubber composition, in addition to components (e)(i), (e)(ii) and (e)(iii) the peroxide curable silicone rubber composition comprises the following components: (a’) organopolysiloxane polymers of the structures described above for the hydrosilylation curable silicone rubber composition with the following difference the polymer may but does not essentially include the unsaturated groups and the polymers may have a significantly greater viscosity of up to several millions of mPa.s at 25oC. Such polymers are often referred to in the industry as “gums” and because their viscosity is so high, they are often defined by their Williams plasticity in accordance with ASTM D-926-08 rather than by viscosity; (b’) reinforcing filler as described above in (b) for the hydrosilylation curable silicone rubber composition; (c’) a peroxide catalyst The peroxide catalyst (c’) of the peroxide curable silicone rubber composition or mixtures of different types of peroxide catalysts may be any of the well-known commercial peroxides used to cure curable silicone compositions. The amount of organic peroxide used is determined by the nature of the curing process, the organic peroxide used, and the composition used. Typically, the amount of peroxide catalyst utilised in a composition as described herein is from 0.2 to 3 wt. %, alternatively 0.2 to 2 wt. % in each case based on the weight of the composition. Suitable organic peroxides are substituted or unsubstituted dialkyl-, alkylaroyl-, diaroyl-peroxides, e.g., benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, ditertiarybutyl peroxide, dicumyl peroxide, t- butyl cumyl peroxide, bis(t-butylperoxyisopropyl) benzene bis(t-butylperoxy)-2,5- dimethyl hexyne 2,4-dimethyl-2,5-di(t- butylperoxy) hexane, di-t-butyl peroxide and 2,5-bis(tert- butyl peroxy)-2,5-dimethylhexane. Mixtures of the above may also be used. Condensation curable (RTV) silicone composition. When the curable silicone composition is a condensation curable (RTV) silicone composition, in addition to components (e)(i), (e)(ii) and (e)(iii) the condensation curable (RTV) silicone composition comprises the following components: Organopolysiloxane polymer (i) of the condensation curable (RTV) silicone composition having an average of least one hydroxyl or hydrolysable group per molecule, of which at least 25 wt. % of polymer (i) has at least two hydroxyl or hydrolysable groups per molecule. The organopolysiloxane polymer (i) of the condensation curable (RTV) silicone composition has an average of at least one hydroxyl or hydrolysable group per molecule, of which at least 25 wt. % of polymer (i) having at least two hydroxyl or hydrolysable groups per molecule may have the structure X3-nRnSi-(Z)d –(O)q- (R1ySiO(4-y) / 2)z –(SiR12- Z)d-Si-RnX3-n (1) in which each X is independently a hydroxyl group, a hydrolysable group or an alkyl group, each R is an alkyl, alkenyl or aryl group, each R1is an X group, alkenyl group or aryl group and Z is a divalent organic group; d is 0 or 1, q is 0 or 1 and d+ q = 1; n is 0, 1, 2 or 3, y is 0, 1 or 2, and z is an integer such that said organopolysiloxane polymer (i) of the condensation curable (RTV) silicone composition has a viscosity of from 750 to 150,000mPa.s at 25oC, alternatively from 750 to 125,000 mPa.s at 25oC. Each X group of organopolysiloxane polymer (i) may be the same or different and can be a hydroxyl group or a condensable or hydrolyzable group or an alkyl group providing at least 25 wt. % of polymer (i) has at least two hydroxyl or hydrolysable groups per molecule. The term "hydrolyzable group" means any group attached to the silicon which is hydrolysed by water at room temperature. The hydrolyzable group X includes groups of the formula -OT, where T is an alkyl group such as methyl, ethyl, isopropyl, octadecyl, an alkenyl group such as allyl, hexenyl, cyclic groups such as cyclohexyl, phenyl, benzyl, beta-phenylethyl; hydrocarbon ether groups, such as 2-methoxyethyl, 2- ethoxyisopropyl, 2-butoxyisobutyl, p-methoxyphenyl or -(CH2CH2O)2CH3. The most preferred hydroxyl group or a condensable or hydrolyzable X groups are hydroxyl groups or alkoxy groups. Illustrative alkoxy groups are methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentoxy, hexoxy octadecyloxy and 2-ethylhexoxy; dialkoxy radicals, such as methoxymethoxy or ethoxymethoxy and alkoxyaryloxy, such as ethoxyphenoxy. The most preferred alkoxy groups are methoxy or ethoxy. When d=1, n is typically 0 or 1 and each X is an alkoxy group, alternatively an alkoxy group having from 1 to 3 carbons, alternatively a methoxy or ethoxy group. In such a case organopolysiloxane polymer (i) has the following structure: X3-nRnSi-(Z)- (R1ySiO(4-y) / 2)z–(SiR12-Z)-Si-RnX3-nWith R, R1, y and z being as described above, n being 0 or 1 and each X being an alkoxy group. Each R is individually selected from alkyl groups, alternatively alkyl groups having from 1 to 10 carbon atoms, alternatively from 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively methyl or ethyl groups; alkenyl groups alternatively alkenyl groups having from 2 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms such as vinyl, allyl and hexenyl groups; and aromatic groups, alternatively aromatic groups having from 6 to 20 carbon atoms or substituted aliphatic organic groups such as 3,3,3-trifluoropropyl groups aminoalkyl groups, polyaminoalkyl groups, and / or epoxyalkyl groups. When X is an alkyl group, the alkyl groups have from 1 to 10 carbon atoms, alternatively from 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively methyl or ethyl groups. Each R1is individually selected from the group consisting of X or R with the proviso that an average of at least one hydroxyl or hydrolysable group is present per molecule, and that at least 25 wt. % of polymer (i) molecules have at least two hydroxyl or hydrolysable groups per molecule. It is possible that some R1groups may be siloxane branches off the polymer backbone which branches may have terminal groups as hereinbefore described. Most preferred R1is methyl. Each Z is independently selected from an alkylene group having from 1 to 10 carbon atoms. In one alternative each Z is independently selected from an alkylene group having from 2 to 6 carbon atoms; in a further alternative each Z is independently selected from an alkylene group having from 2 to 4 carbon atoms. Each alkylene groups may for example be individually selected from an ethylene, propylene, butylene, pentylene and / or hexylene group. Additionally, n is 0, 1, 2 or 3, d is 0 or 1, q is 0 or 1 and d+ q = 1. In one alternatively when q is 1, n is 1 or 2 and each X is an OH group or an alkoxy group. In another alternative when d is 1 n is 0 or 1 and each X is an alkoxy group. Organopolysiloxane polymer (i) of the condensation curable (RTV) silicone composition has a viscosity of from 750 to 150,000mPa.s at 25oC, alternatively from 750 to 125,000 mPa.s at 25oC mPa.s at 25oC, alternatively from 1,000 to 100,000mPa.s at 25oC, alternatively from 1,000 to 75,000mPa.s at 25oC alternatively from 1,000 to 60,000mPa.s at 25oC. Whilst y is 0, 1 or 2, substantially y= 2, e.g., at least 90% alternatively 95% of R1ySiO(4-y) / 2 groups are characterized with y = 2. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter cone and plate fixture with the cone having a 1.988° cone angle, and 104 micrometer truncation at a shear rate of 1s-1. Organopolysiloxane polymer (i) of the condensation curable (RTV) silicone composition can be a single siloxane represented by Formula (1) or it can be mixtures of organopolysiloxane polymers represented by the previously mentioned formula. Hence, the term "siloxane polymer mixture" in respect to component (i) is meant to include any individual organopolysiloxane polymer (i) or mixtures of organopolysiloxane polymer (i). The Degree of Polymerization (DP), (i.e., in the above formula substantially z), is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule of silicone. Synthetic polymers invariably consist of a mixture of macromolecular species with different degrees of polymerization and therefore of different molecular weights. There are different types of average polymer molecular weight, which can be measured in different experiments. The two most important are the number average molecular weight (Mn) and the weight average molecular weight (Mw). The Mn and Mw of a silicone polymer can be determined by gel permeation chromatography (GPC) with precision of about 10-15%. This technique is standard and yields Mw, Mn and the polydispersity index (PI). The degree of polymerisation (DP) =Mn / Mu where Mn is the number- average molecular weight coming from the GPC measurement and Mu is the molecular weight of a monomer unit. PI=Mw / Mn. The DP is linked to the viscosity of the polymer via Mw, the higher the DP, the higher the viscosity. Organopolysiloxane polymer (i) is going to be present in an amount of from 10 to 60 wt. %, alternatively 10 to 55 wt. %, alternatively 20 to 55 wt. % of the composition. Cross-linker (ii) of the condensation curable (RTV) silicone composition Cross-linker (ii) may be any suitable cross-linker used in condensation curable (RTV) silicone compositions. The cross-linker (ii) may be one or more silanes or siloxanes which contain silicon bonded hydrolysable groups such as acyloxy groups (for example, acetoxy, octanoyloxy, and benzoyloxy groups); ketoximino groups (for example dimethyl ketoximo, and isobutylketoximino); alkoxy groups (for example methoxy, ethoxy, iso-butoxy and propoxy) and alkenyloxy groups (for example isopropenyloxy and 1-ethyl-2-methylvinyloxy). In the case of siloxane based cross-linkers the molecular structure can be straight chained, branched, or cyclic. Cross-linker (ii) of the condensation curable (RTV) silicone composition preferably has at least three or four hydroxyl and / or hydrolysable groups per molecule which are reactive with the hydroxyl and / or hydrolysable groups in organopolysiloxane polymer (i). When the cross-linker is a silane and when the silane has a total of three silicon-bonded hydroxyl and / or hydrolysable groups per molecule, the fourth group is suitably a non-hydrolysable silicon-bonded organic group. These silicon-bonded organic groups are suitably hydrocarbyl groups which are optionally substituted by halogen such as fluorine and chlorine. Examples of such fourth groups include alkyl groups (for example methyl, ethyl, propyl, and butyl); cycloalkyl groups (for example cyclopentyl and cyclohexyl); alkenyl groups (for example vinyl and allyl); aryl groups (for example phenyl, and tolyl); aralkyl groups (for example 2-phenylethyl) and groups obtained by replacing all or part of the hydrogen in the preceding organic groups with halogen. Preferably however, the fourth silicon- bonded organic groups are methyl. Silanes and siloxanes which can be used as cross-linkers (ii) of the condensation curable (RTV) silicone composition include alkyltrialkoxysilanes such as methyltrimethoxysilane (MTM) and methyltriethoxysilane, alkenyltrialkoxy silanes such as vinyltrimethoxysilane and vinyltriethoxysilane, isobutyltrimethoxysilane (iBTM). Other suitable silanes include ethyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, alkoxytrioximosilane, alkenyltrioximosilane, 3,3,3-trifluoropropyltrimethoxysilane, methyltriacetoxysilane, vinyltriacetoxysilane, ethyl triacetoxysilane, di-butoxy diacetoxysilane, phenyl-tripropionoxysilane, methyltris(methylethylketoximo)silane, vinyl-tris-methylethylketoximo)silane, methyltris(methylethylketoximino)silane, methyltris(isopropenoxy)silane, vinyltris(isopropenoxy)silane, ethylpolysilicate, n-propylorthosilicate, ethylorthosilicate, dimethyltetraacetoxydisiloxane. The cross-linker used may also comprise any combination of two or more of the above. Alternatively, cross-linker (ii) of the condensation curable (RTV) silicone composition may comprise a silyl functional molecule containing two or more silyl groups, each silyl group containing at least one –OH or hydrolysable group, the total of number of –OH groups and / or hydrolysable groups per cross-linker molecule being at least 3. Hence, a disilyl functional molecule comprises two silicon atoms each having at least one hydrolysable group, where the silicon atoms are separated by an organic or siloxane spacer. Typically, the silyl groups on the disilyl functional molecule may be terminal groups. The spacer may be a polymeric chain having a siloxane or organic polymeric backbone. In the case of such siloxane or organic based cross-linkers the molecular structure can be linear, branched, cyclic or macromolecular. In the case of siloxane-based polymers the viscosity of the cross-linker will be within the range of from 0.5 mPa.s to 75,000 mPa.s at 25°C, alternatively from 0.5 mPa.s to 40,000mPa.s at 25oC. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter cone and plate fixture with the cone having a 1.988° cone angle, and 104 micrometer truncation at a shear rate of 1s-1. For example, cross-linker (ii) of the condensation curable (RTV) silicone composition may be a disilyl functional polymer, that is, a polymer containing two silyl groups, each having at least one hydrolysable group such as described by the formula RnSi(X)3-n–R3- Si(X)3-nRn where each R, X and n may be individually selected as hereinbefore described above. R3is an alkylene (divalent hydrocarbon radical), alternatively an alkylene group having from 1 to 10 carbon atoms, or further alternatively 1 to 6 carbon atoms or a combination of said divalent hydrocarbon radicals and divalent siloxane radicals. Preferred di-silyl functional polymer cross-linkers have n= 0 or 1, X=OMe and R3being an alkylene group with 4 to 6 carbons. Examples of disilyl polymeric cross-linkers with a silicone or organic polymer chain bearing alkoxy functional end groups include polydimethylsiloxanes having at least one trialkoxy terminal where the alkoxy group may be a methoxy or ethoxy group. Examples might include or 1, 6- bis(trimethoxy silyl)hexane, hexamethoxydisiloxane, hexaethoxydisiloxane, hexa-n- propoxydisiloxane, hexa-n-butoxydisiloxane, octaethoxytrisiloxane, octa-n-butoxytrisiloxane and decaethoxy tetrasiloxane. The amount of cross-linker (ii) present in the composition will depend upon the nature of the cross- linker and in particular, the molecular weight of the molecule selected. The compositions suitably contain cross-linker in at least a stoichiometric amount as compared to organopolysiloxane polymer (i) described above. One or more reinforcing fillers and / or non-reinforcing fillers (iii) of the condensation curable (RTV) silicone composition The one or more reinforcing fillers identified as component (iii) herein may for example be selected from precipitated silica, fumed silica, precipitated calcium carbonate, or a mixture of two or more thereof. Typically, the surface area of the reinforcing filler (iii) is at least 15 m² / g in the case of precipitated calcium carbonate measured in accordance with the BET method (ISO 9277: 2010), alternatively 15 to 50 m² / g, alternatively 15 to 25 m² / g. Silica reinforcing fillers have a typical surface area of at least 50 m² / g in accordance with the BET method (ISO 9277: 2010). In the case of high surface area fumed silica and / or high surface area precipitated silica, these may have surface areas of from 75 to 400 m² / g measured in accordance with the BET method (ISO 9277: 2010), alternatively of from 100 to 300 m² / g in accordance with the BET method (ISO 9277: 2010). The reinforcing fillers (iii) of the condensation curable (RTV) silicone composition may be hydrophobically treated for example with one or more aliphatic acids, e.g., a fatty acid such as stearic acid or a fatty acid ester such as a stearate, or with organosilanes, organosiloxanes, or organosilazanes hexaalkyl disilazane or short chain siloxane diols to render the filler(s) hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other adhesive components. Specific examples organosilanes, organosiloxanes, or organosilazanes may include, but are not restricted to, silanol terminated trifluoropropylmethylsiloxane, silanol terminated vinyl methyl (ViMe) siloxane, silanol terminated methyl phenyl (MePh) siloxane, liquid hydroxyldimethyl-terminated polydiorganosiloxane containing an average from 2 to 20 repeating units of diorganosiloxane in each molecule, hydroxyldimethyl terminated phenylmethyl Siloxane, hexaorganodisiloxanes, such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes, such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane and tetramethyldi(trifluoropropyl)disilazane; hydroxyldimethyl terminated polydimethylmethylvinyl siloxane, octamethyl cyclotetrasiloxane, and silanes including but not limited to methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlorotrimethyl silane, dichlorodimethyl silane, trichloromethyl silane. The surface treatment of the fillers makes them easily wetted by component (I). These surface modified fillers are preferably in a finely divided form and do not clump and can be homogeneously incorporated into the silicone polymer (i) of the condensation curable (RTV) silicone composition. This results in improved room temperature mechanical properties of the uncured compositions. The fillers may be pre-treated or may be treated in situ when being mixed with component (i). A small amount of water can be added together with the silica treating agent(s) as processing aid. Depending on the filler(s) chosen the reinforcing fillers (iii) may be present in an amount of from 2.5 to 60 wt. % of the composition. In the case when the selected fillers are precipitated silica and / or fumed silica or a combination thereof the inorganic fillers (iii) are present in a range of from about 5.0 to 35 wt. % of the composition, alternatively of from 5 to 30 wt. % of the composition, alternatively of from 5 to 25 wt. % of the composition. However, when reinforcing filler (iii) is precipitated calcium carbonate, the composition will tend to include a larger wt. % of the composition, e.g., from 25 to 60 wt. % of the composition, alternatively of from 30 to 60 wt. % of the composition, alternatively of from 35 to 55 wt. % of the composition. When component (iii) of the condensation curable (RTV) silicone composition is a mixture of silica and precipitated calcium carbonate the wt. % will typically somewhere therebetween. Non-reinforcing fillers, Non-reinforcing fillers, which might be used alone or in addition to the above reinforcing filler in the condensation curable (RTV) silicone composition include aluminite, calcium sulphate (anhydrite), gypsum, nepheline, syenite, quartz, ground calcium carbonate, calcium sulphate, magnesium carbonate, clays such as kaolin, aluminium trihydroxide, magnesium hydroxide (brucite), graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g., zarachite, barium carbonate, e.g., witherite and / or strontium carbonate e.g., strontianite. Silicates from the group consisting of olivine group; garnet group; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The olivine group comprises silicate minerals, such as but not limited to, forsterite and Mg2SiO4. The garnet group comprises ground silicate minerals, such as but not limited to, pyrope; Mg3Al2Si3O12; grossular; and Ca2Al2Si3O12. Aluminosilicates comprise ground silicate minerals, such as but not limited to, sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5. The ring silicates group comprises silicate minerals, such as but not limited to, cordierite and Al3(Mg,Fe)2[Si4AlO18]. The chain silicates group comprises ground silicate minerals, such as but not limited to, wollastonite and Ca[SiO3]. The sheet silicates group comprises silicate minerals, such as but not limited to, mica; K2AI14[Si6Al2O20](OH)4; pyrophyllite; Al4[Si8O20](OH)4; talc; Mg6[Si8O20](OH)4; serpentine for example, asbestos; Kaolinite; Al4[Si4O10](OH)8; and vermiculite. The non-reinforcing fillers may also be hydrophobically treated as described above. Condensation Catalyst (iv) of the condensation curable (RTV) silicone composition Some of the compositions disclosed herein do not require a catalyst to aid in curing the composition although suitable catalysts may be used if appropriate. Hence, the composition may comprise a condensation catalyst (iv). This increases the speed at which the composition cures. The catalyst (iv) chosen for inclusion in a particular silicone sealant composition depends upon the speed of cure required. Catalyst (iv) of the condensation curable (RTV) silicone composition may be a tin-based catalyst. Tin based catalysts are typically used in compositions which are stored in two parts and mixed together immediately prior to use as discussed further below. Suitable tin based condensation catalysts (iv) include tin triflates, dialkyltin compounds, selected from dimethyltin di-2- ethylhexanoate, dimethyltin dilaurate, di-n-butyltin diacetate (DBTDA), di-n-butyltin di-2- ethylhexanoate, dimethyltin dineodecanoate (DMTDN), dioctyltin dineodecanoate (DOTDN), di-n- butyltin dicaprylate, di-n-butyltin di-2,2-dimethyl octanoate, di-n-butyltin octanoate, di-n- butyltin dilaurate (DBTDL), di-n-butyltin distearate, di-n-butyltin dimaleate, di-n-butyltin dioleate, di-n- octyltin di-2-ethylhexanoate, di-n-octyltin di-2,2-dimethyl octanoate, di-n-octyltin dimaleate, Di-n- octyl tin dilaurate (DOTDL), di-n-butyl tin oxide, tin butyrate, butyltintri-2-ethylhexoate, tin naphthenate, tin octoate, triethyltin tartrate and di-n-octyl tin oxide. The tin catalyst may be present in an amount of from 0.001 to 3 wt. % of the composition; alternatively, 0.1 to 0.75 wt. % of the composition. Titanate and / or zirconate-based catalysts (iv) of the condensation curable (RTV) silicone composition are more often utilised in one-part sealant compositions, i.e., compositions not requiring mixing prior to use. Suitable titanate and / or zirconate-based catalysts (iv) i.e., alkoxy titanates and alkoxy zirconates may comprise a compound according to the general formula M[OR22]4 where M is titanium or zirconium and each R22may be the same or different and represents a monovalent, primary, secondary or tertiary aliphatic hydrocarbon group which may be linear or branched containing from 1 to 10 carbon atoms. Optionally the titanate or zirconate may contain partially unsaturated groups. However, preferred examples of R22include but are not restricted to methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl and a branched secondary alkyl group such as 2, 4-dimethyl-3-pentyl. Preferably, when each R22is the same, R22is an isopropyl, branched secondary alkyl group or a tertiary alkyl group, in particular, tertiary butyl. Suitable examples include for the sake of example, tetra n-butyl titanate, tetra t-butyl titanate, tetra t-butoxy titanate, tetraisopropoxy titanate and diisopropoxydiethylacetoacetate titanate. Alternatively, the titanate or zirconate may be chelated. The chelation may be with any suitable chelating agent such as an alkyl acetylacetonate such as methyl or ethylacetylacetonate. Alternatively, the titanate may be monoalkoxy titanates bearing three chelating agents such as for example 2-propanolato, tris isooctadecanoato titanate. The titanium or zirconium catalyst may be present in an amount of from 0.01 to 3 wt. % of the composition; alternatively, 0.1 to 0.75 wt. % of the composition. Optional additives Other ingredients which may be included in the condensation curable (RTV) silicone composition include but are not restricted to plasticisers or extenders, rheology modifiers; adhesion promoters, pigments, heat stabilizers, flame retardants, UV stabilizers, chain extenders, cure modifiers, electrically and / or heat conductive fillers, and fungicides and / or biocides and the like. Plasticizer or extender The condensation curable (RTV) silicone composition composition as hereinbefore described may comprise a plasticizer or extender (sometimes referred to as a processing aid) in the form of a silicone or organic fluid which is unreactive with organopolysiloxane polymer(s) (i) and / or crosslinker(s) (ii), whether reactive or unreactive. If present the plasticizer or extender content will be present in an amount of from 5 to 30 wt. % of the composition, alternatively from 5 to 25 wt. % or the composition. These may function as component (e)(ii) if an unreactive component (e)(ii) is desired and their viscosity is suited for the purpose. Examples of non-reactive silicone fluids useful as plasticizers include polydiorganosiloxanes such as polydimethylsiloxane having terminal triorganosiloxy groups wherein the organic substituents are, for example, methyl, vinyl or phenyl or combinations of these groups. Such polydimethylsiloxanes can for example have a viscosity of from about 5 to about 100,000 mPa.s at 25oC. When present, these can be in Part A or in Part B of the two-part composition with a cross-linker and catalyst and if the viscosity of the plasticiser id 15,000mPa.s at 25oC it may additionally function as a non-reactive swelling agent (e) (ii). Alternatively compatible organic plasticisers may be utilised additionally to or instead of the silicone fluid plasticiser include dialkyl phthalates wherein the alkyl group may be linear and / or branched and contains from six to 20 carbon atoms such as dioctyl, dihexyl, dinonyl, didecyl, diallanyl and other phthalates, and analogous adipate, azelate, oleate and sebacate esters; polyols such as ethylene glycol and its derivatives; and organic phosphates such as tricresyl phosphate and / or triphenyl phosphates. Examples of extenders for use in compositions herein include mineral oil based (typically petroleum based) paraffinic hydrocarbons, mixtures of paraffinic and naphthenic hydrocarbons, paraffin oils comprising cyclic paraffins and non-cyclic paraffins and hydrocarbon fluids containing naphthenics, polycyclic naphthenics and paraffins, or polyalkylbenzenes such as heavy alkylates (alkylated aromatic materials remaining after distillation of oil in a refinery). Examples of such extenders are discussed in GB2424898 the content of which is hereby enclosed by reference. The condensation curable room temperature vulcanisable (RTV) silicone composition, said composition may be stored as one-part compositions or in multiple parts (e.g., two or three parts) prior to use, with the parts being mixed together shortly before use in the latter case. In the case of multiple part condensation curable compositions, as the chemically tuned preformed silicone elastomeric particulates (e)(i) have been chemically tuned, they may be introduced into any or all of the Parts after the preformed silicone elastomeric particulates (e)(i) have been chemically tuned and pre-swollen by (e)(ii). Alternatively, the chemically tuned preformed silicone elastomeric particulates (e)(i) may undergo the swelling step (4) in one or more of the multiple part compositions. In such a case the swelling agent (e)(ii) being utilised is mixed into the Part selected typically before the addition of chemically tuned preformed silicone elastomeric particulates (e)(i). Again, in one alternative, when some of organopolysiloxane polymer (i) has a sufficiently low viscosity (i.e., less than 15,000mPa.s) said organopolysiloxane polymer (i) may be utilised to function as component (e)(ii), in which case the chemically tuned preformed silicone elastomeric particulates (e)(i) can be added directly into the selected Part composition and be allowed to swell for a period of time. When the preformed silicone elastomeric particulates (e)(i) and component (e)(ii) are mixed together in a pre-mix, the pre-mix of component (e) may, once said period of time allowed for swelling the preformed silicone elastomeric particulates (e)(i) has expired, be added directly into the selected Part or may be kept separately alone or with additional organopolysiloxane polymer (i) which and then mixed into the final composition simultaneously with the other parts. Most often one-part compositions are catalysed with a titanium and / or zirconium-based catalyst. These tend to cure via a skin or diffusion cured process are applied in a layer that is thinner than typically 15 mm. and takes place by the formation of a cured skin at the composition / air interface subsequent to the sealant / encapsulant being applied on to a substrate surface. Thereafter, the cure speed is dependent on the speed of diffusion of moisture from the sealant / encapsulant interface with air to the inside (or core), leading to a gradual thickening of the cured skin over time from the outside / surface to the inside / core. In contrast the two-part compositions cure throughout the bulk of the sealant and therefore tend to be faster curing and curing typically starts once the multiple parts are mixed together. In the two-part compositions the chemically tuned preformed silicone elastomeric particulates (e)(i) may be introduced into either part. The incorporation of the mechanically recycled elastomeric silicone rubber particulates reduces the carbon footprint by reusing the particulates to replace new silicone ingredients and the swelling step (4) caused by the mixing of components (e)(i) and (e)(ii) provides a route for reusing the recycled particulates. The cured materials made from the compositions herein may be used for example in adhesives, refrigerant spacers, potting agents and coatings and sealants such as weatherproofing sealants and coatings and / or tire sealants in the case of condensation cured (RTV) silicone elastomers or in or as airbag coatings, gaskets and seals, adhesives, coatings, molded rubber articles, hoses and tubing like medical tubing and potting agents or the like, for silicone rubber elastomers prepared from hydrosilylation curable compositions and peroxide cure compositions. Examples In the following examples, the compositions are defined in weight % (wt. %) unless otherwise stated. Vinyl group and Si-H group content was measured by Infrared spectroscopy in accordance with ASTM E168 using standards of the carbon double bond stretch and silicon-hydrogen bond stretch respectively. Unless otherwise indicated all viscosity measurement given for hydrosilylation and peroxide cure systems are zero-shear viscosity (ηo) values, obtained by extrapolating to zero the value taken at low shear rates (or simply taking an average of values) in the limit where the viscosity-shear rate curve is rate-independent, which is a test-method independent value provided a suitable, properly operating rheometer is used. For example, the zero-shear viscosity of a substance at 25 °C may be obtained by using commercial rheometers such as an Anton-Parr MCR-301 rheometer or a TA Instruments AR- 2000 rheometer equipped with cone-and-plate fixtures of suitable diameter to generate adequate torque signal at a series of low shear rates, such as 0.01 s-1, 0.1 s-1and 1.0 s-1while not exceeding the torque limits of the transducer. Alternatively, the viscosity measurements may be obtained using an ARES-G2 rotational rheometer, commercially available from TA Instruments using a steady rate sweep from 0.1 to 10 s-1on a 25 mm cone and plate. If the zero-shear plateau region cannot be observed at shear rates accessible to the rheometer or viscometer, we report the viscosity measured at a standard shear rate of 0.1 s-1at 25 °C. For the condensation cure compositions, the viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter cone and plate fixture with the cone having a 1.988° cone angle, and 104 micrometer truncation at a shear rate of 1s-1. All viscosity measurements were taken at 25oC unless otherwise indicated. All Shore hardness measurements were measured using the Shore A hardness scale or in the case of softer elastomers using the Shore 00 scale as defined ASTM D2240-15. Swelling Reference Examples Hydrosilylation cure In order to show that low viscosity organopolysiloxane polymers will swell a hydrosilylation cured silicone elastomer when the elastomer is soaked / immersed in a low viscosity silicone fluid, the following experiment was undertaken. A slab of a cured silicone liquid silicone rubber material was prepared following the instructions supplied with the product for mixing the two-part compositions provided. Three 1-inch x 1-inch x 0.08 inch (2.54cm x 2.54 cm x 2mm) rectangular samples were cut from the slabs. The three rectangular samples were immersed in three dimethylvinyl terminated polydimethylsiloxanes having different viscosities, the first had an approximate viscosity of 30mPa.s, the second fluid had an approximate viscosity of 430mPa.s and the third fluid had an approximate viscosity of 44,000mPa.s in each case the values provided were zero-shear values measured as described above at 25oC. Each sample remained immersed in the respective fluid for 24 hours after which they were analysed for changes. It was found that the sample immersed in the fluid having a viscosity of 44,000mPa.s gained no mass and did not change in size. The sample immersed in the 430 mPa.s fluid had an 8% increase in mass and size. The sample immersed in 30 mPa.s fluid had a 30% increase in mass and size. Hence, it can be seen that swelling did take place when the samples were immersed in low viscosity silicone fluids, but no noticeable swelling occurred when immersed in the fluid having a viscosity of 44,000mPa.s. Condensation Cure An analogous experiment was undertaken in order to show that low viscosity silicone fluids swell a condensation cured silicone elastomer when the elastomer was immersed in a low viscosity silicone fluid. A condensation cured slab of silicone elastomer, made from a two-part sealant composition using a tin catalyst, was prepared and the test repeated. In the case of the condensation cured samples, it was found that the sample immersed in 44,000mPa.s gained no mass and did not change in size. The sample soaked in 430 mPa.s fluid had an 8% increase in mass and size. The sample immersed in 30 mPa.s fluid had a 30% increase in mass and size. Hence, it can be seen that swelling does take place when the samples were immersed in low viscosity silicone fluids and as a consequence similar swelling occurs to the preformed silicone elastomeric particulates. Laboratory Preparation of particulates In one example, cured condensation cured silicone elastomer block samples were shredded with a paper shredder and cut with scissors until they were of a predetermined size of less than 2cm particle size. They were then fed into a MikroTMUMP-B mill commercially available from Hosokawa Micron Corporation. The shredded / cut rubber samples were mixed with dry ice (the dry ice had been previously crushed to a powder using mortar and pestle) in a weight ratio of approximately 1:1 in order to reduce the temperature of the rubber and help stiffen it for milling. The cured silicone elastomer / dry ice mixture was then fed into the mill using a knife blade rotor rotating at an rpm of > 10,000. The rubber was then allowed to leave the milling chamber through a stainless-steel screen when it was cut finer than the hole size of the screen. The screen had 2-3 mm diameter round holes for a first pass. The cured silicone elastomer milled in the first pass was then subjected to a second pass with dry ice again as before and fed through the MikroTMUMP-B mill for a second pass this time using a 1mm slotted screen. Analytical Assessment of Particle Size. The particle size distribution of the milled preformed silicone elastomeric particulates was measured using laser diffraction. A Beckman CoulterTMLS 13320 Particle Size Analyzer with the Tornado (dry) module was used. Approximately 25 mL of a milled bulk solids sample was added into a vial, which was placed in the LS 13320 Tornado module which was then activated. When activated, the Tornado module automatically vacuumed the sample past a laser and the diffraction signal of the sample was measured. Beckman CoulterTMsoftware then used to deconvolute the diffraction signal to a particle size distribution determined using Fraunhofer diffraction model. In the following examples a hydrosilylation cure liquid silicone rubber composition was utilised to provide a series of examples and comparative examples. The composition was prepared as two-Part compositions, Part A and Part B. To make the final compositions the Parts A & B were intermixed before cure. The composition was kept in the two parts prior to use to ensure premature cure was avoided. The compositions of the basic liquid silicone rubber composition used in the examples Parts A and B are provided below in Tables 1a and 1b and prior to use the compositions were mixed together in a 1 : 1 weight ratio. Table 1a: Liquid silicone rubber composition used in the preparation of Ref.1, comparative 1, Ex.1 and Ex.3 (in wt. %) Material Part Part Part A(1) B(1) B(2) g a . . The Shore A hardness for the above composition once cured, as defined ASTM D2240-15 was 10 and this is depicted as Ref.1 in the following Tables.

[0002] Table 1b: Liquid silicone rubber composition 2 used in the preparation of Ref.2, comparative 2, Ex.2 and Ex.4 (in wt. %) Material Part Part Part A(2) B(3) B(4) 6 0 as 50 . . Cross-linker 1 in the above compositions of Tables 1a was a trimethyl terminated methylhydrogen dimethylsiloxane polymer having a zero-shear viscosity of about 5 mPa.s. Cross-linker 2 in the above compositions of Tables 1b was a trimethyl terminated methylhydrogen dimethylsiloxane polymer having a zero-shear viscosity of about 15 mPa.s. In Tables 2a and 2b the relative amounts of the silicone rubber compositions identified in Tables 1a and 1b above together with the amounts of swelling agents and capping agents used in each of C.1 to C.2 and Ex.1 to Ex. 4 are provided. Table 2a: Components utilised in Ref.1 and 2 and Comparative 1 and 2 (in parts by weight per 100 part by weight of relative to Part B(1) of LSR 1 or Part B(3) of LSR 2 (Table 1b)) Ref.1 C.1 Ref.2 C.2 Table 2b: Components utilised in Ex.1 to 4 (in parts by weight per 100 parts by weight of Part B(2) of LSR 1 (Table 1a) or Part B(4) of LSR 2 (Table 1b) as required Ingredient type Ex.1 Ex.2 Ex.3 Ex.4 Part B(2) of LSR 1 (Table 1a) 100 100 reactive swelling agents are expressed as parts by weight per 100 parts by weight of the respective Part B composition. In Tables 2a and 2b Physically recycled silicone rubber particulates 1 were prepared from a hydrosilylation cured liquid silicone rubber (LSR) coating composition containing an HMDZ treated fumed silica having a Shore A hardness of about 10. Physically recycled silicone rubber particulates 2 were prepared from a hydrosilylation cured liquid silicone rubber (LSR) coating composition containing an HMDZ treated fumed silica- containing having a Shore A hardness of about 40. It had a Shore A hardness value of about 40 prior to being turned into particulates measured in accordance with ASTM D 2240-15. Reactive swelling agent used was a vinyldimethyl terminated polydimethylsiloxane having a zero- shear viscosity of about 450mPa.s. Non-Reactive swelling agent was Trimethylsiloxy terminated polydimethylsiloxane with a zero- shear viscosity of about 10,000mPa.s. Capping Agent was 1-dodecene in a diluent in the form of trimethylsiloxy terminated polydimethylsiloxane with a zero-shear viscosity of 10,000 mPa.s. In the method used in examples 1 to 4 the hydrosilylation cured physically recycled silicone rubber selected were first mixed with a non-reactive swelling agent in the form of trimethylsiloxy terminated polydimethylsiloxane with viscosity of 10,000 mPa.s after which the capping agent 1- dodecene (C10H21CH=CH2) was added. The resulting mixture was then left for a period of about 72 hours at room temperature and pressure to enable the capping agent to react with residual Si-H groups in or on said preformed silicone elastomeric particulates (e)(i) and simultaneously for the non-reactive capping agent to penetrate and swell said preformed silicone elastomeric particulates (e)(i). The resulting mixture of passivated preformed silicone elastomeric particulates (e)(i) in the nonreactive swelling agent was then introduced into the relevant part B composition and were able to undergo further swelling in the additional presence of a reactive swelling agent. Whilst the passivated preformed silicone elastomeric particulates (e)(i) may be mixed into either the Part A or Part B compositions given the chemical tuning, in this case passivation, of the excess Si-H groups by reaction with the capping agent but for the sake of these examples the relevant Part B composition of Table 1a or 1b was prepared and the mixture resulting from the capping activity was mixed therewith for a period of 1 hour. After completion of the swelling steps the resulting mixture containing 100 parts by weight of the Part B(1), B(2) B(3) or B(4) compositions respectively incorporating the swelled particulates was inter-mixed with 100 parts by weight of the part A(1) composition of LSR 1 or the Part A(2) composition of LSR 2 (in a Part A : Part B weight ratio of 1 : 1 excluding the particulates) resulting in there being equivalent to about 9.88 wt. % (unswelled weight) of particulates in the total composition of Part A + Part B as well as 2.27 wt.% of the non-reactive swelling agent, and about 0.09 wt.% of the capping agent. The loading of capping agent was selected to be molar equivalent to the number of moles of residual Si-H in the regrind, assuming full vinyl conversion during the original cure of the elastomer prior to physicalrecycling. The resulting hydrosilylation curable silicone rubber composition was cured by compression molding rectangular slabs of dimensions 5 in by 5 in by 0.08 in (12.7cm x 12.7 cm x 0.2mm) of the different compositions at 150 °C for 10 minutes. Subsequent to cure, the resulting cured samples were analysed for their physical properties in accordance with the ASTM methods described below and the results are depicted in Table 3a (Shore A and Shore 00 hardness) and 3b (tensile testing). For tensile testing, tensile bars with a 40 mm gauge length were cut from the rectangular slab using a metal die, otherwise Tensile strength, elongation at break and modulus at 100% elongation results were determined in accordance with ASTM D412. Five replicates were performed for each sample. Table 3a: Shore A results for Ref.2, C.2, Ex.2 and Ex.4 and Shore 00 results for Ref.1, C.1, Ex. 1 and Ex.3(ASTM D2240-15). Shore A Shore 00 In the above, Shore 00 measurements were only taken for the softer materials which would register results. Table 3b: Tensile properties for Ref.1 C.1 Ex.1 and Ex.3 and comparisons were made to Ref.1 (tested in accordance with ASTM D412). Modulus at % of Ref. % % of % of 100% 1 (M100) Elongation Ref.1 Tensile Ref.1 As prev having a Shore A hardness value of 10 which gave a Shore 00 hardness of about 71. Samples C.1, Ex.1, and Ex.3 all comprise cured materials made from the LSR composition described in Table 1a but containing preformed silicone elastomeric particulates (e)(i) identified as Mechanically recycled silicone rubber 1 in Table 2a and 2b above. C.1 is made from the simplest preformed silicone elastomeric particulates (e)(i) containing composition using particulates which have not been passivated. Ex.1 is similar to C.1 but is in accordance with this disclosure as the particulates were passivated before swelling. Ex.3 is similar to Ex.1 with the addition of reactive swelling agent. A large increase in elongation at break with minimal change in tensile strength is observed for Ex.1 and Ex.3 compared to C.1. Such an increase in elongation without a corresponding decrease in tensile strength is generally desirable and reflects the advantages of the unique network structure enabled by the capping agent. Furthermore, the modulus at 100% elongation of Ex.1 and Ex.3 are lower than that of C.1, approaching that of the Ref.1 but without the hardening effect seen in C.1. The lower moduli for the capping agent samples Ex.1 and Ex.3 demonstrates that the Si-H capping agent successfully passivated residual Si-H in the particulates present and does not suggest chemical reaction with the LSR composition of Table 1a during cure which would create localized regions of high crosslink density and thus high hardness. These localized regions of high crosslink density pose an issue for obtaining high elongation materials, as they concentrate stress and promote premature fracture. The high elongations of Ex.1 and Ex.3 compared to C.1 thus demonstrate the advantages of the capping agent approach. Table 3c: Tensile properties for Ref.2, C.2, Ex.2 and Ex.4 and comparisons were made to Ref.2 (tested in accordance with ASTM D412). Modulus at % of Ref. % % of % of 100% 2 (M100) Elongation Ref.2 Tensile Ref.2 As pre erial having a Shore A hardness value of 35. Samples C.2, Ex.2, and Ex.4 all comprise cured materials made from the LSR composition described in Table 1b but containing preformed silicone elastomeric particulates (e)(i) identified as physically recycled silicone rubber 2 in Table 2a and 2b above. C.2 is made from the simplest preformed silicone elastomeric particulates (e)(i) containing composition using particulates which have not been passivated. Ex.2 is similar to C.2 but is in accordance with this disclosure as the particulates were passivated before swelling. Ex.4 is similar to Ex.2 with the addition of reactive swelling agent. Similar results are observed for the higher durometer series as well. Ex.2 and Ex.4 have higher elongation at break and similar or even higher tensile strengths as C.2. Like the low Shore hardness materials based on Ref.1 above the moduli at 100% extension of Ex.2 and Ex.4 approach that of the Ref.2, while C.2 has a slightly higher modulus. Rationale for the improved performance of the medium Shore hardness materials based around the Ref.2 formulation follows that of the low Shore hardness materials series based on Ref.1, namely that capping agent minimizes chemical reaction between cured silicone material and preformed silicone elastomeric particulates which cause regions of high local crosslink density. Overall, the low and medium durometer series demonstrate the potential broad applicability of this formulation approach for incorporating recycled silicone rubber.

Claims

CLAIMS 1. A method of preparing a curable silicone composition comprising the steps of (1) obtaining preformed silicone elastomeric particulates (e)(i) having an average unswollen particle size of 1 mm or less, cured by a predetermined cure process; (2) chemically tuning said preformed silicone elastomeric particulates (e)(i) by mixing the preformed silicone elastomeric particulates (e)(i) with a capping agent in the form of a compound having a single reactive chemical group (e)(iii) which will undergo a chemical reaction with anticipated residual chemical groups in or on said preformed silicone elastomeric particulates (e)(i) and allowing same to react for a period of time; to provide chemically tuned preformed silicone elastomeric particulates (e)(i); (3) optionally isolating said chemically tuned preformed silicone elastomeric particulates (e)(i); (4) mixing the chemically tuned preformed silicone elastomeric particulates (e)(i) with an organopolysiloxane polymer swelling agent (e)(ii) having a zero-shear viscosity of less than or equal to (≤) 15,000 mPa.s at 25oC for a defined period to enable said organopolysiloxane polymer swelling agent (e)(ii) to penetrate and swell said chemically tuned preformed silicone elastomeric particulates (e)(i) to form component (e); (5) forming a step (5) mixture by mixing component (e) from step (4) into at least part of a curable silicone composition; (6) if required mixing the step (5) mixture with the remainder of said curable silicone composition.

2. A method of preparing a curable silicone composition in accordance with claim 1 wherein Step (4), Step (5) and optionally Step (6) may be undertaken together as a single step or wherein Step (2) Step (4), Step (5) and optionally Step (6) may be undertaken together as a single step.

3. A method of preparing a curable silicone composition in accordance with claim 1 or 2 wherein the curable silicone composition is selected from a hydrosilylation curable silicone composition, a peroxide cure silicone composition or a condensation curable (RTV) silicone composition.

4. A method of preparing a curable silicone composition in accordance claim 1, 2 or 3 wherein preformed silicone elastomeric particulates (e)(i) are obtained from silicone rubber elastomers prepared from hydrosilylation curable silicone compositions or condensation cured silicone compositions.

5. A method of preparing a curable silicone composition in accordance with claim 4 wherein preformed silicone elastomeric particulates (e)(i) are obtained from silicone rubber elastomers prepared from hydrosilylation curable silicone compositions and the capping agent is selected from one or more linear or branched compounds containing one alkene group or one alkyne group in each case comprising from 2 to 20 carbons, per molecule or a monoalkenyl-functional monomer or oligomer or a monoalkynyl-functional monomer or oligomer,alkylvinyl ethers, monovinyl polydimethylsiloxane, acrylates and methacrylates, polyalkylene glycols comprising one alkenyl or alkynyl group, monoallyloxy polyalkylene glycols, styrene, a- methyl styrene, acrylic acid, and hexafluoroisopropyl methacrylate.

6. A method of preparing a curable silicone composition in accordance with claim 4 wherein preformed silicone elastomeric particulates (e)(i) are obtained from silicone rubber elastomers condensation cured silicone compositions and the capping agent is selected from alkoxysilanes, alkenyl trialkoxysilanes, alkenyldialkoxyalkylsilanes, alkenylalkoxydialkylsilanes, glycidoxyalkyltrialkoxysilanes, glycidoxyalkyldialkoxyalkylsilanes, glycidoxyalkylalkoxydialkylsilanes and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

7. A method of preparing a curable silicone composition in accordance with any one of claims 1, 2, 3, 45 or 6 wherein component (e)(ii) has a zero-shear viscosity of from 100 to 5,000mPa.s at 25oC.

8. A method of preparing a curable silicone composition in accordance with any one of claims 1, 2, 3, 4, 5, 6 or 7 wherein the preformed silicone elastomeric particulates (e)(i) are physically recycled and / or reclaimed silicone elastomeric particulates prepared by grinding, milling, or pulverizing silicone elastomers into particulates.

9. A curable silicone composition which is the product of the method in accordance with any one of claims 1 to 8.

10. A curable silicone composition obtained or obtainable by a method comprising the steps of one of claims 1 to 8.

11. A cured silicone material which is the cured product of the curable silicone composition in accordance claim 9 or 10.

12. Use of a compound having a single reactive chemical group (e)(iii) to chemically tune preformed silicone elastomeric particulates (e)(i) in a method to make a curable silicone composition comprising the steps of (1) obtaining preformed silicone elastomeric particulates (e)(i) having a an average unswollen particle size of 1 mm or less, cured by a predetermined cure process; (2) chemically tuning said preformed silicone elastomeric particulates (e)(i) by mixing the preformed silicone elastomeric particulates (e)(i) with a capping agent in the form of a compound having a single reactive chemical group (e)(iii) which will undergo a chemical reaction with anticipated residual chemical groups in or on said preformed silicone elastomeric particulates (e)(i) and allowing same to react for a period of time; to provide chemically tuned preformed silicone elastomeric particulates (e)(i); (3) optionally isolating said chemically tuned preformed silicone elastomeric particulates (e)(i); (4) mixing the chemically tuned preformed silicone elastomeric particulates (e)(i) with an organopolysiloxane polymer swelling agent (e)(ii) having a zero-shear viscosity of less than or equal to (≤) 15,000 mPa.s at 25oC for a defined period to enable said organopolysiloxane polymerswelling agent (e)(ii) to penetrate and swell said chemically tuned preformed silicone elastomeric particulates (e)(i) to form component (e); (5) forming a step (5) mixture by mixing component (e) from step (4) into at least part of a curable silicone composition; (6) if required mixing the step (5) mixture with the remainder of said curable silicone composition.

13. Use of a compound having a single reactive chemical group (e)(iii) to chemically tune preformed silicone elastomeric particulates (e)(i) in a method in accordance with claim 12 wherein Step (4), Step (5) and optionally Step (6) are undertaken together as a single step or wherein Step (2) Step (4), Step (5) and optionally Step (6) may be undertaken together as a single step.

14. Use in accordance with claim 12 or 13 wherein preformed silicone elastomeric particulates (e)(i) are obtained from silicone rubber elastomers prepared from hydrosilylation curable silicone compositions d the capping agent is selected one or more linear or branched compounds containing one alkene group or one alkyne group in each case comprising from 2 to 20 carbons, per molecule or a monoalkenyl-functional monomer or oligomer or a monoalkynyl-functional monomer or oligomer, alkylvinyl ethers, monovinyl polydimethylsiloxane, acrylates and methacrylates, polyalkylene glycols comprising one alkenyl or alkynyl group, monoallyloxy polyalkylene glycols; styrene, a-methyl styrene, acrylic acid, and hexafluoroisopropyl methacrylate.

15. Use in accordance with claim 12 or 13 wherein preformed silicone elastomeric particulates (e)(i) are obtained from silicone rubber elastomers condensation cured silicone compositions and the capping agent is selected from alkoxysilanes,alkenyl trialkoxysilanes, alkenyldialkoxyalkylsilanes, alkenylalkoxydialkylsilanes, glycidoxyalkyltrialkoxysilanes, glycidoxyalkyldialkoxyalkylsilanes, glycidoxyalkylalkoxydialkylsilanes and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

16. Use in accordance with claim 12, 13, 14 or 15 wherein the preformed silicone elastomeric particulates (e)(i) are physically recycled and / or reclaimed silicone elastomeric particulates.

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