Polymeric materials

Abstract

A formulation for treatment of a polymeric material, for example recycled polyolefin, to enable relatively high quantities of recycled polyolefin, for example PCR, to be combined with virgin resin to achieve excellent mechanical properties comprises a radical generator and a branching agent. The radical generator may be a peroxide, a hindered amine, a nitroxide or a metal radical source and the branching agent may include a moiety: (I); or a moiety (II); and may be selected from 1 -Dodecene, Diethylmaleate, 1- Hexadecene, 1-Eicosene, Methyl Oleate, Triphenylethylene, 1,6-Hexanediol dimethacrylate and Benzyl methacrylate.

Description

[0001] POLYMERIC MATERIALS P45320 This invention relates to polymeric materials and particularly, although not exclusively, relates to polyolefins. Preferred embodiments relate to polymeric materials comprising polyethylene and / or polypropylene; and / or such polymeric materials which include relatively high levels of recycled polyolefin, for example post-consumer resin (PCR) and / or post-industrial resin (PIR). It is becoming increasingly important to maximize the amounts of recycled polyolefin used in producing new molded articles. For example, PCR (which may itself comprise a mixture of polyolefin resins and contamination from other polymers and organic or inorganic species) may be mixed with virgin resin to produce a mass of polymeric material which is formed into pellets or granules by, for example, melt- blending. The pellets or granules may then be extruded or injection molded to produce new articles. However, when quantities of recycled resin (e.g. PCR) increase above a nominal level (e.g. typically 25 wt%), mechanical properties of polymeric materials tend to deteriorate with consequent challenges in processing and articles produced may have relatively poor mechanical properties. For example, inclusion of recycled resin may disadvantageously impact key properties of the polymeric material, such as melt flow, tensile strength, tensile modulus, tensile elongation, flexural strength, flexural modulus, Heat Deflection Temperature (HDT), Vicat softening temperature and / or resistance to environmental stress cracking (ESCR). If PCR used has many heat histories, it could form gels or molecular weight may be lowered during processing due to chain scission. The net impact is that end use applications of polymeric materials incorporating PCR may lead to molded articles having product defects and generate excessive scrap. The use of recycled resin as described may lead to particular challenges in ESCR with a risk that, if too high a level of recycled resin is used, molded articles produced may be susceptible to failure under constant stress below the resin’s yield point. Packaged consumer goods, often produced by extrusion blow molding, are increasingly required to be produced with increasing levels of PCR. However, the greater the level of PCR, the greater the risk of ESCR failure. A number of commercial products are available, directed at solving some of the problems described herein. For example, CaCO3 may be added. However, this provides limited improvement in key mechanical properties and, disadvantageously, very high additional levels are required. Compatibilisers are known but tend to require high additional levels and tend to reduce the flexural strength of the article, in turn limiting its applicability. Special resin grades are commercially available; however, their utility reduces with increasing recycle content. It is an object of the preferred embodiments of the present invention to address the above-described problems. It is an object of preferred embodiments of the present invention to enable higher quantities of recycled polyolefin, for example PCR, to be usable without significantly negatively impacting mechanical properties (eg impact strength or flexural properties) of the polyolefin. It is an object of preferred embodiments of the present invention to enable higher quantities of recycled polyolefin, for example PCR, to be usable without significantly negatively impacting ESCR. According to a first aspect of the invention, there is provided a formulation for treatment of a polymeric material, the formulation comprising: (i) a radical generator; and (ii) a branching agent. Advantageously, a formulation as described herein can be used to treat recycled polyolefin and enable relatively high quantities of recycled polyolefin, for example PCR, to be combined with virgin resin to achieve excellent mechanical properties, including excellent resistance to ESCR. Said radical generator may be organic or an inorganic complex. For example, it may be an inorganic salt or a transition metal complex. Said radical generator may be a thermal radical initiator, a thermal cationic initiator, a photo radical initiator or a photo cationic initiator. Said radical generator is preferably a thermal radical initiator. Said radical generator may be a substituted or unsubstituted phthalimide, peroxyketal, alkyl or aryl peroxide, organic or inorganic radical generator, a combination of one or more radical generators, a polymeric radical initiator, an entity which generates radicals by a macroparticle such as polystyrene or polytetrafluoroethylene. Said radical generator may be a peroxide, a hindered amine, a nitroxide or a metal radical source. Preferably, said radical generator is stable and storable at room temperature (25 °C). Preferably, said radical generator is processible at 220 °C, for example at typical HDPE processing temperature. Preferably, said radical generator has a self-accelerating decomposition temperature (SADT) of more than 80 °C. This may be determined on the radical generator per se as described in Assessment 2. Preferably, said radical generator has a t ½ (half-life period) in the range 100-200°C, more preferably in the range 100-150°C. Preferably, said radical generator has the capability to initiate radical polymerization. Said radical generator, for example peroxide, preferably has a decomposition temperature, suitably measured by Differential Scanning Calorimetry (DSC), of at least 100°C, for example in the range 100°C to 300°C. Said radical generator is preferably a solid peroxide, preferably with a relatively high half life period and SADT as described. Usually peroxides with relatively high molecular weight and with bulky groups are thermally stable and, as such, are preferred. During melt-processing, for example reactive extrusion, preferred peroxides take part in a reaction by the radical generation. Said radical generator is preferably a peroxide. Said radical generator may be a peroxide with alkyl or aryl groups as substituents; or a peroxide with an active functional group selected from: acrylate, ester, ether, diimide and cyclic or acyclic hydrocarbons. Said radical generator may be selected from 1,1-Di(tert-amylperoxy)cyclohexane, Di(4- tert.butylcyclohexyl)peroxydicarbonate, Dibenzoyl peroxide, 2,2-Di(tert.butylperoxy)butane, Dicetylperoxydicarbonate, 1,1-Di(tert.butylperoxy)cyclohexane, Acetylacetone peroxide, tert.Butylperoxybenzoate, Methyl ethyl ketone peroxide / Cumyl hydroperoxide, Cumyl hydroperoxide, Methyl isobutyl ketone peroxide, Methyl ethyl ketone peroxide, tert.Amylperoxy-2-ethylhexylcarbonate, 2,5-Dimethyl-2,5-di(tert.butylperoxy)hexane, tert.Butylperoxy-2-ethylhexylcarbonate, Di(2,4- dichlorobenzoyl)peroxide, Dicumylperoxide, 2,5-Dimethyl-2,5-di(tert.butylperoxy)hexane, Di(tert.butyl)peroxide, Di(tert.butyl)peroxide, 2,5-Dimethyl-2,5-di(tert.butylperoxy)hexyne-3, Di(2- ethylhexyl)peroxydicarbonate, Di(3,5,5-trimethylhexanoyl)peroxide, Dilauroyl peroxide, Dimyristylperoxydicarbonate, tert.Butylperoxy-2-ethylhexylcarbonate, tert.Butylperoxy-2- ethylhexanoate, tert.Amylperoxy-2-ethylhexanoate, tert.Butylperoxyneodecanoate, tert.Butylperoxy- 3,5,5-trimethylhexanoate, 1,1-Di(tert.butylperoxy)-3,3,5-trimethylcyclohexane, 1,1- Di(tert.butylperoxy)cyclohexane, Di(4-tert.butylcyclohexyl)peroxydicarbonate, Dimyristylperoxydicarbonate, Acetylacetone peroxide, Methyl ethyl ketone peroxide, 1,1- Di(tert.butylperoxy)-3,3,5-trimethylcyclohexane, Acetylacetone peroxide, Methyl ethyl ketone peroxide, Acetylacetone peroxide, Methyl ethyl ketone peroxide / Cumyl hydroperoxide, Methyl ethyl ketone peroxide / Acetylacetone peroxide, tert.Butylperoxybenzoate, Acetylacetone peroxide, Methyl isobutyl ketone peroxide, Methyl ethyl ketone peroxide, Acetylacetone peroxide, tert.Butylperoxybenzoate, Acetylacetone peroxide, Peroxide Dye Concentrates, Disuccinoylperoxide, tert.Amyl hydroperoxide, tert.Amylperoxy-2-ethylhexanoate, Tert. Amylperoxy-2-ethylhexylcarbonate, tert.Amylperoxypivalate, tert.Butyl hydroperoxide, tert.Butylperoxyacetate, tert.Butylperoxy-2-ethylhexanoate, tert.Butylperoxy-2- ethylhexylcarbonate, tert.Butyl-peroxy-isobutyrate, tert.Butylperoxy-3,5,5-trimethylhexanoate, tert.Butylperoxyneodecanoate, tert.Butylperoxypivalate, 1,1-Di(tert.butylperoxy)-3,3,5- trimethylcyclohexane, 1,3-bis(tert-butylperoxyisopropyl) benzene, 1,4-bis(tert-butylperoxyisopropyl) benzene, Tert-butylcumylperoxide, n-butyl-4,4-di(tert-butylperoxy)valerate, t-butyl peroctoate, t-butyl peroxypivalate, di-tertiary butyl peroxide, alpha-cumyl peroxyneodecanoate, 3-hydroxy-1,1-dimethyl butyl-peroxyneodecanoate, Di(4-methylbenzoyl) peroxide and 3,3,5,7,7-Pentamethyl-1,2,4-trioxepane Said radical generator may be a di-(optionally-substituted)alkyl peroxide. Where it is optionally- substituted, it may be substituted by a hydrocarbon moiety (eg containing hydrogen and carbon atoms only), for example a phenyl moiety. Said radical generator may be a dialkyl peroxide. Said radical generator may be selected from dicumyl peroxide, 1,1-Di(tert.butylperoxy)cyclohexane, tert.Butylperoxybenzoate, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane and 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate. Said radical generator may include one or more peroxide (O-O) groups in combination only with moieties which include carbon and hydrogen atoms only. Said radical generator may include peroxide groups in combination with moieties of formula -CR50R51R52wherein R50, R51and R52independently are selected from phenyl and methyl groups and the free carbon atom is preferably directly bonded to an oxygen atom of a peroxide group. One preferred group of radical generators have a t ½ (half-life period) in the range 100-150°C. Preferred examples include 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexyne-3 3,6,9-Triethyl-3,6,9-trimethyl-1,4,7- triperoxonane, Di(tert-butyl)peroxide, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane, Di(tert-butylperoxy- isopropyl)benzene, tert-Butyl cumyl peroxide, Di-(tert-amyl)-peroxide, Dicumyl peroxide,Butyl 4,4- di(tert-butylperoxy)valerate, tert-Butylperoxybenzoate, 2,2-Di(tert-butylperoxy)butane, tert-Amyl peroxy- benzoate, tert-Butylperoxy-acetate , tert-Butylperoxy-(2-ethylhexyl)carbonate, tert-Butylperoxy isopropyl carbonate, tert-Butyl peroxy-3,5,5-trimethyl-hexanoate, 1,1-Di(tert-butylperoxy)cyclohexane, tert-Amyl peroxyacetate,tert-Amylperoxy-(2-ethylhexyl)carbonate,1,1-Di(tert-butylperoxy)-3,5,5- trimethylcyclohexane,1,1-Di(tert-amylperoxy)cyclohexane, tert-Butyl-monoperoxy-maleate,1,1’- Azodi(hexahydrobenzonitrile), Di(4-methylbenzoyl) peroxide and 3,3,5,7,7-Pentamethyl-1,2,4- trioxepane. Said radical generator may be selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane and dicumyl peroxide. Said branching agent may be an olefin with an internal or terminal C=C double bond; and / or said branching agent may be congugated or non-conjugated; and / or said olefin may be substituted or unsubstituted; and / or said olefin may have a molecular weight in the range of 50-1500, and / or said olefin may have a C4-C100 carbon chain; and / or said olefin may be an oligomer or low molecular weight polymer; and / or said olefin may be linear or branched; and / or said olefin may include a reactive group which may include an epoxide, cyanide or oxazinone functional group; and / or said olefin may be an alkyne and / or liquid rubber, for example polyisobutylene or polybutadiene. Said branching agent may be an α-olefin or an activated alkene, for example one arranged to react with a radical source to generate a new covalent linkage. Said branching agent may include a moiety (I); or a moiety (II). When said branching agent includes a moiety of Formula I, it may be of Formula wherein R1represents a hydrogen atom or an optionally-substituted moiety which may include carbon and hydrogen atoms only and / or may include saturated or unsaturated hydrocarbon moieties and / or may be an optionally-substituted alkyl or alkenyl group and / or may include one or more functional groups selected from ether, nitro, ester, amide and hydroxy; and R2represents an optionally-substituted moiety which may include carbon and hydrogen atoms only and / or may include saturated or unsaturated hydrocarbon moieties and / or may be an optionally- substituted alkyl or alkenyl group and / or may include one or more functional groups selected from ether, nitro, ester, amide and hydroxy; and / or R1and R2together define an optionally-substituted cyclic structure. When said branching agent include a moiety of formula II, it may be of formula wherein: R3and R4independently represent optionally-substituted alkyl or aryl groups, or represents an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV. An optionally-substituted alkyl group may be an optionally-substituted C1-C10 alkyl groups. Such an alkyl group may be optionally- substituted, for example by ester moieties. An aryl group may be an optionally-substituted, for example, unsubstituted phenyl group; and R10represents a hydrogen atom or an optionally-substituted alkyl or aryl groups, or represents an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV. An optionally-substituted alkyl group may be an optionally-substituted C1-C10 alkyl groups. Such an alkyl group may be optionally- substituted, for example by ester moieties. An aryl group may be an optionally-substituted, for example, unsubstituted phenyl group. When R10represents a hydrogen atom, R3and R4may independently represent optionally-substituted alkyl groups, for example optionally-substituted C1-C10 alkyl groups, or represents an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV. Such alkyl groups may be independently optionally-substituted, for example by ester moieties. In one embodiment, R3, R4and R5may independently represent optionally-substituted, preferably unsubstituted, alkyl or aryl groups. In the embodiment, preferably at least one, preferably each, of R3, R4and R5independently represent optionally-substituted, preferably unsubstituted, aryl groups, for example phenyl groups. When R10represents an optionally-substituted alkyl or aryl groups, it preferably represents an optionally- substituted, preferably unsubstituted, aryl group, for example a phenyl group. Said branching agent may include 4 to 100, preferably 6 to 50, more preferably 10 to 30 carbon atoms. Said branching agent may have a melting point of greater than 10oC, for example of greater than 50oC or greater than 90oC; and said melting point may be less than 300oC or less than 200oC. Said branching agent may have a boiling point of greater than 150oC, for example of greater than 175oC; and said boiling point may be less than 400oC or less than 300oC or less than 250oC. For the avoidance of doubt, the aforementioned boiling points refer to the branching agent in isolation. In some embodiments, a liquid carrier, as hereinafter described, may have the effect of reducing the vapor pressure of the branching agent in the formulation. When said branching agent includes a moiety of formula I and / or is of formula III, it may be an α-olefin. Preferred α-olefin include 6 to 30, or 8 to 22 or 10 to 25 carbon atoms. A preferred α-olefin is 1-dodecene. When said branching agent includes a moiety of formula I and / or is of formula III, it may be selected from 4-Vinylanisole, α-Methylstyrene, 3-Nitrostyrene, Benzyl methacrylate, 1,1-Diphenylethylene, Camphene, Diacetone acrylamide, 1,9-decadiene, Vinylcyclohexene and Eugenol. In some cases, when said branching agent includes a moiety of formula III, it may be 3,9-Divinyl-2,4,8,10- tetraoxaspiro[5.5]undecane. When branching agent includes a moiety of formula IV, R3may be selected from a moiety of formula or an alkyl group, preferably a linear alkyl group, which is optionally-substituted by an ester moiety; and R4may selected from a moiety of formula (V) or an alkyl group, preferably a linear alkyl group, which is optionally-substituted by an ester moiety. When said branching agent includes a moiety of formula IV, R3and R4may independently be selected from (VI); and (VII) wherein the * carbon indicates the position of bonding to the double bond of moiety IV and n, m and q are integers, preferably in the range 1 to 10. In preferred embodiments, n may be in the range 1 to 3; m may be in the range 2 to 10, preferably 4 to 9; and q may be in the range 2 to 10, preferably 4 to 9. When said branching agent includes a moiety of formula IV, preferably at least one of R3or R4includes a moiety (V) or (VI). When said branching agent includes a moiety of formula IV, preferably both R3and R4are not a moiety of formula VII. Examples of compounds of formula IV include methyl oleate and diethyl maleate. Examples of branching agents include 1-Dodecene, Diethylmaleate, 1-Hexadecene, 1-Eicosene, Methyl Oleate, Triphenylethylene, 1,6-Hexanediol dimethacrylate and Benzyl methacrylate. Said formulation may include 0.0001 to 50.0 wt% of said radical generator. Said formulation may include 1 to 10wt%, preferably 1 to 8wt%, more preferably 2 to 7wt% of said radical generator. The sum of the wt% of all radical generators in the formulation may be in the range 0.0001 to 50.0wt%. Said sum may be in the range 1 to 10wt%, preferably 1 to 8wt%, more preferably 2 to 7wt%. Said formulation may include 0.0001 to 99.0 wt% of said branching agent. Said formulation may include 1 to 50wt%, preferably 5 to 30wt%, more preferably 10 to 25wt% of said branching agent. The sum of the wt% of all branching agents in the formulation may be in the range 0.0001 to 99.0 wt%. Said sum may be in the range 1 to 50wt%, preferably 5 to 30wt%, more preferably 10 to 25wt%. In said formulation, a ratio defined as the wt% of said radical generator divided by the wt% of said branching agent may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. In said formulation, a ratio defined as the sum of the wt% of all radical generators divided by the sum of the wt% of all branching agents may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. In an embodiment (A1), said formulation may not include a carrier (eg a component which is inert and / or is arranged to dissolve or disperse the radical generator and / or branching agent but otherwise is not intended to react or form reactive species when the formulation is used to treat a polyolefin) separate from said radical generator and said branching agent. In this case, the sum of the wt% of all radical generators and all branching agents in said formulation may be at least 90wt%, for example at least 94wt%, at least 98wt% or at least 99wt%. In embodiment (A1), said branching agent may be selected to act both as a branching agent and a carrier for the radical generator. In this case, said branching agent is preferably a liquid and said radical generator may be a liquid which is miscible with the branching agent or may be a solid which is finely dispersed in the branching agent. In embodiment (A1), said formulation may include 1 to 50 wt% of said radical generator and 50 to 99 wt% of said branching agent. Preferably, said formulation include 10 to 50 wt% of said radical generator and 50 to 90 wt% of said branching agent. In said embodiment (A1), said formulation may include 1 to 50 wt% in total of radical generators and 50 to 99 wt% in total of branching agents. Preferably, said formulation include 10 to 50 wt% in total of radical generators and 50 to 90 wt% in total of branching agents. In said embodiment (A1), a ratio defined as the wt% of said radical generator divided by the wt% of said branching agent may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. In said embodiment (A1), a ratio defined as the sum of the wt% of all radical generators divided by the sum of the wt% of all branching agents may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. Said formulation of the first aspect may be a liquid formulation or a solid formulation, for example a solid masterbatch. Said formulation may comprise: (i) said radical generator; (ii) said branching agent; and (iii) a carrier. The radical generator and branching agent are preferably dispersed, preferably substantially homogeneously, in the carrier. The radical generator and branching agent are preferably compatible with the carrier. Preferably, unless otherwise stated herein, the reference to “liquid” and “solid” refer to a state at 25°C and standard pressure (101325Pa). When said formulation is a liquid, the carrier is preferably a liquid. Said carrier may have a boiling point at 760mmHg in accordance with ASTM D1078 in the range 150 to 1150°C, preferably in the range 275°C to 1000°C or in the range 275°C to 500°C. Said carrier may have a viscosity measured using a Brookfield viscometer, spindle 2, 20rpm at 20°C in the range 50-3500cP, more preferably in the range 200-1800cP. Said carrier may comprise a hydrocarbon-containing liquid. Said carrier may comprise one or more liquids, for example, one or more hydrocarbon-containing liquids. Said carrier may comprise a low molecular weight wax. Said carrier may comprise a triglyceride. Said carrier may comprise liquid rubber. Said carrier may comprise mineral oil. When said formulation is a liquid, said radical generator is preferably fully dissolved in the carrier at the concentration used or is itself a liquid. When said formulation is a liquid, said branching agent is preferably fully dissolved in the carrier at the concentration used or is a liquid. Examples of liquid rubbers include polyisobutylene of low MW (eg 1000 – 2500) and / or having viscosity in the range 200 – 4750 cSt; polybutadiene (MW 5000 – 10000); and ethylene-alpha-olefin co-polymer (MW 2700 – 16000). In general terms, said carrier may have a viscosity in the range 400- 50000 cps. When said carrier comprises one or more liquids, it may comprise one or more of the carriers referred to. For example, said carrier may comprise a mixture of mineral oil (eg 10 to 30wt%) and polyisobutylene and / or liquid rubber (eg 70 to 90wt%). When said formulation is a solid, said carrier may comprise a polyolefin and / or a thermoplastic elastomer (TPE). Said carrier may comprise a carrier typically used in solid masterbatches. Said carrier may comprise a polyolefin, for example polyethylene (eg HDPE or LDPE) or polypropylene, a styrenic block polymer (eg styrene-ethylene-butylene-styrene (SEBS) or styrene-butadiene copolymer (SBC), ethylene-vinyl acetate (EVA) or ethylene Propylene Rubber (EPR). Said formulation which includes said carrier may include 1 to 10wt%, preferably 1 to 8wt%, more preferably 2 to 7wt% of said radical generator. The sum of the wt% of all radical generators in the formulation may be in the range 1 to 10wt%, preferably 1 to 8wt%, more preferably 2 to 7wt%. Said formulation which includes said carrier may include 5 to 30wt%, preferably 10 to 25wt% of said branching agent. The sum of the wt% of all branching agents in the formulation may be in the range 5 to 30wt%, more preferably 10 to 25wt%. In said formulation which includes said carrier, a ratio defined as the wt% of said radical generator divided by the wt% of said branching agent may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. In said formulation which includes said carrier, a ratio defined as the sum of the wt% of all radical generators divided by the sum of the wt% of all branching agents may be in the range 1:1 to 1:100, for example in the range 1:1 to 1:10. Said formulation may include 50 to 94 wt%, preferably 70 to 90wt% of said carrier. The sum of the wt% of all carriers in said formulation may be in the range 50 to 94 wt%, preferably 70 to 90wt%. In said formulation, a ratio defined as the wt% of all carriers divided by the sum of the wt% of all radical generators may be in the range 1 to 95 or 2 to 90. In said formulation, a ratio defined as the wt% of all carriers divided by the sum of the wt% of all branching agents may be in the range 1 to 95 or 2 to 90. Said formulation may include a radical mediator / polymerization inhibitor which is suitably able to accept or donate a radical and prevent pre-reaction of monomers, for example the branching agent. Said radical mediator / polymerization inhibitor may include sterically hindered hydroxy groups. Said radical mediator / polymerization inhibitor may be selected from a hydroquinone, for example monomethyl ether hydroquinone, TEMPO derivatives, lipophilic organic compounds, for example butylated hydroxytoluene (BHT), Copper(II) Dibutyldithiocarbamate, cobalt 2-ethylhexanoate and phenothiazine. Preferably, said radical mediator / polymerization inhibitor is selected from BHT, hydroquinone and TEMPO. Said formulation may include 0 to 5wt%, for example 0.001 to 3 wt%, of said radical mediator / polymerization inhibitor. Said formulation may include a colorant which may be a pigment. Said formulation may include 0 to 50wt%, for example 0 to 10wt%, of colourant, in total. Colorant may be included to counter any discoloration in the polymeric material to which the formulation may be added as described herein. Said formulation may include an antioxidant / heat stabilizer. Said formulation may include an antioxidant which may be a phenolic, phosphite, thio-ether or organic sulfide. Said formulation may include an antioxidant / free radical scavenger / anti-crosslinking agent selected from: glutathione, lipoic acid, vitamins such as ascorbic acid (vitamin C), vitamin B, vitamin D, vitamin-E, tocopherols (synthetic or natural, alpha-, gamma-, delta-), acetate vitamin esters, water soluble tocopherol derivatives, tocotrienols, water soluble tocotrienol derivatives; melatonin, carotenoids including carotenes, lutein, pycnogenol, glycosides, trehalose, polyphenols and flavonoids, quercetin, lycopene, lutein, selenium, nitric oxide, curcuminoids, 2-hydroxytetronic acid; cannabinoids, synthetic antioxidants such as tertiary butyl hydroquinone, 6-amino-3-pyrodinoles, butylated hydroxyanisole, butylated hydroxytoluene, ethoxyquin, tannins, propyl gallate, other gallates, Aquanox™ family; Irganox® and Irganox® B families including Irganox® 1010, Irganox® 1076, Irganox® 1330, Irganox® 1035; Irgafos® family; phenolic compounds with different chain lengths, and different number of OH groups; enzymes with antioxidant properties such as superoxide dismutase, herbal or plant extracts with antioxidant properties such as St. John's Wort, green tea extract, grape seed extract, rosemary, oregano extract, mixtures, derivatives, analogues or conjugated forms of these. Said formulation may include an antioxidant which is a primary antioxidant with reactive OH or NH groups such as hindered phenols or secondary aromatic amines; or secondary antioxidants such as organophosphorus compounds or thiosynergists; or multifunctional antioxidants, hydroxylamines, or carbon centered radical scavengers such as lactones or acrylated bis-phenols. Antioxidants may be selected individually or used in any combination. Antioxidants may be used in conjunction with hydroperoxide decomposers. Said formulation may include 0.0001-50%, preferably less than 5wt%, more preferably 0.0001-2wt%, of antioxidant / heat stabilizer in total. When said formulation is a liquid, said formulation may include a viscosity control agent. A viscosity control agent may be a surfactant and / or fumed silica. A viscosity control agent may be a wax, silicon dioxide, povidone, carbomer, poloxamer, carboxymethyl cellulose, hydroxyethyl cellulose or a polyacrylic acid. Said formulation may include 0 to 50wt%, 0.0001 to 50wt%, 0.0001 to 5wt% or 0.0001 to 3wt% of viscosity control agent. In some cases, said formulation may include one or more fillers (eg inorganic fillers, such as CaCO3). Preferably, said formulation includes less than 1wt%, less than 0.5wt% or less than 0.1wt% of fillers, for example inorganic fillers. According to a second aspect of the invention, there is provides a mixture comprising: (a) a polymeric material; (b) a radical generator or a residue thereof; (c) a branching agent or a residue thereof; and, optionally (but preferably) (d) a carrier. Preferably, the mixture comprises said polymeric material and the formulation of the first aspect. Said mixture may comprise a residue of said radical generator produced by heat processing, for example reactive extrusion of, the mixture. Said mixture may comprise a residue of said branching agent produced by heat processing, for example reactive extrusion of, the mixture. When said carrier is unfunctionalised (eg it comprises an oil such as mineral oil), said carrier may be solubilized in the polymeric material. When said carrier is functionalized, said carrier may undergo cleavage or reaction produced by heat processing, for example reactive extrusion of, the mixture. Said polymeric material preferably comprises one or more polyolefins. It preferably comprises at least two polyolefins from different sources and / or which have different identity and / or properties. Said polymeric material preferably comprises polyethylene. It may include 50 to 100wt% polyethylene. Said polymeric material preferably comprises recycled material, for example PCR or PIR. It may comprise polyethylene PCR, especially HDPE PCR. Said polymeric material preferably comprises at least 25wt% recycled material, for example PCR. Said polymeric material may comprise 25 to 100wt%, 25 to 75wt% or 25 to 50wt%, recycled material, for example PCR. Said polymeric material may comprise up to 50wt% of polypropylene (PP), for example 10 to 50wt% PP. Compositions of PCR may vary as between one another. For example, PCR may include inorganic contamination and / or may be contaminated with fillers. For example, said PCR may include up to 3wt%, for example 0.5 to 1wt% of inorganic contamination. Said polymeric material may comprise virgin polymer, for example virgin polyethylene, especially virgin HDPE. Said polymeric material preferably comprises at least 25wt% virgin polymer. Said polymeric material may comprise 25 to 75wt% or 50 to 75wt% virgin polymer. In some cases, said polymeric material may comprise about 100wt% of virgin polymer, for example PE. Said radical generator, branching agent and carrier may have any feature as described in the first aspect. Said mixture may be in a solid form, for example in the form of pellets or granules. Said mixture may include at least 90wt%, preferably at least 94wt%, more preferably at least 96wt%, of polyolefins in total. It may include less than 99wt% or less than 98wt% of polyolefins in total. Said mixture may include at least 90wt%, preferably at least 94wt%, more preferably at least 96wt%, of polyethylene in total. It may include less than 99wt% or less than 98wt% of polyethylene in total. According to a third aspect, there is provided a product of the treatment (eg melt-processing and / or reaction, for example reactive extrusion) of: (a) a polymeric material; with (b) a radical generator; (c) a branching agent; and, optionally (but preferably) (d) a carrier. The product may be produced by the treatment (eg melt-processing and / or reaction, for example reactive extrusion) of said polymeric material with the formulation of the first aspect. Said product may be in the form of granules or pellets. Alternatively, said product may be in the form of a molded article, for example produced by extrusion, such as by extrusion blow molding, by compression molding or by injection molding. The molded article may be a packaging article such as a receptacle or container or a sheet. Said polymeric material, radical generator, branching agent and carrier may have any feature as described in the first and / or second aspects. According to a fourth aspect of the invention, there is provided a method of improving mechanical properties of a polymeric material which, optionally, includes recycled polymeric material, the method comprising: (i) selecting a first mass of polymeric material, wherein said first mass includes a first polymeric material and, optionally, recycled polymeric material; (ii) contacting said first mass with said formulation of the first aspect and / or producing a mixture of the second aspect; and (iii) melt-processing, for example by reactive extrusion, the combination produced in step (ii). Said first polymeric material may comprise a polyolefin for example polyethylene and / or polypropylene. Said first polymeric material is preferably not recycled polymeric material, for example it is not PCR. Said first polymeric material may be virgin polymeric material, for example virgin polyolefin. It may be virgin polyethylene or virgin polypropylene. It is preferably virgin polyethylene. Said first polymeric material may comprise at least 80 wt%, at least 90 wt% or at least 95 wt% of virgin polyolefin. Said first polymeric material may comprise at least 80 wt%, at least 90 wt% or at least 95 wt% of virgin polyethylene; or said first polymeric material may comprise at least 80 wt%, at least 90 wt% or at least 95 wt% of virgin polypropylene. Said recycled polymeric material may, if included, comprise scrap polymeric material, PCR or PIR. Said recycled polymeric material may comprise recycled polyolefin, for example recycled polyethylene and / or polypropylene. Said recycled polymeric material may comprise PCR. A polymeric material produced in the method may include 50 to 100wt% of said first polymeric material and 0 to 50wt% of recycled polymeric material. Said polymeric material produced in the method may include 50 to 80wt% of said first polymeric material and 20 to 50wt% of recycled polymeric material. The polymeric material produced in the method may be in the form of granules or pellets. The polymeric material may in the form of a molded article, for example produced by extrusion, such as by extrusion blow molding, compression molding or injection molding. The molded article may be a packaging article such as a receptacle or container. The molded article may be an extrusion blow molded article. The molded article may be a packaging article such as a receptacle or container or a sheet. Said method is preferably a method of improving ESCR of said polymeric material. For example, when ESCR is determined as described herein, there may be an improvement of at least 50%, preferably at least 100%, more preferably at least 200%. Such high % improvement may be required to ensure rHDPE can be utilized in higher value applications such as consumer goods. According to a fifth aspect, there is provided a molded article, pellets or granules which comprise a polymeric material, for example as described herein (eg it comprises the first polymeric material and optional recycled polymeric material of the fourth aspect) and a trace amount of one or more of the following: a radical generator or a residue thereof as described herein; a branching agent or a residue thereof as described herein; and / or a carrier or a residue thereof as described herein. The polymeric material is suitably modified by use of the formulation of the first aspect, for example such that the branching agent in the formulation used becomes part of the polymer backbone with an associated advantageous effect on mechanical properties. The reaction of the branching agent with the polymer backbone may be determine via analytical methods designed to analyse polymer fragments such as pyrolysis GC-MS. The presence of remnants / degradation of the radical generators and branching agent may be determined by LC-MS / GC-MS. Preferably, said molded article includes a trace amount of both said radical generator or a residue as described herein and said branching agent or a residue as described herein. Any feature of any aspect of any invention described herein may be combined with any feature of any other invention described herein mutatis mutandis. Specific embodiments of the invention will now be described, by way of example. The following materials are referred to hereinafter: Virgin HDPE - refers to HDPE grade H055025 from Ineos; PCR HDPE - refers to commercially-available recycled HDPE; Luperox 101 – refers to 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane Cas No 78-63-7 Molecular weight: 290.4 g Melting point: 8°C Active oxygen: 11.1% from Arkema; Luperox 101XL45 - refers to 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane Cas No 78-63-7 blend with calcium carbonate and silica from Sigma Aldrich; The following assessments were undertaken: Assessment 1 – Environmental Stress-Cracking Test (ESCR) This was assessed by a bent strip test, using ASTM D1693 under Condition B. At condition B, a bent strip of a test resin is placed in a 10% Igepal® solution at 50 °C. The strip is a plaque that is of dimension L x B x Thickness (4 cm x 1.5 cm x 3mm). A 0.5 mm notch is cut across the strip to create a stress point before immersion into the 10% Igepal® solution at 50 °C. The time to failure is measured. Assessment 2 – Self-accelerating decomposition temperature (SADT) measurement A test peroxide is placed in an oven set at a test temperature. A timer is started when peroxide reaches 2°C below the test temperature. The oven is held at constant temperature for up to one week or, until a runaway event occurs. A peroxide “Passes” if it does not exceed the test (oven) temperature by 6°C within one week. A peroxide “Fails” if it exceeds the test temperature by 6°C within one week. The test is repeated in 5°C increments until a failure is reached. The failure temperature is reported as the SADT for that peroxide. Secondary information about the violence of the decomposition can also be recorded. Example 1 – General procedure for preparation of HDPE granules from recycled HDPE. Virgin HDPE and PCR HDPE in 50:50 wt% ratio were mixed with a formulation comprising a carrier, peroxide and branching agent. After thorough mixing, the samples were processed in a twin-screw extruder at a nominal temperature screw profile of 230° C and productivity of 15 kg / h to produce granules. Example 2 – General procedure for compression or injection molding of granules. Granules as prepared in Example 1 were compression molded or injection molded to prepare test pieces for testing as described. In the case of compresssion molding, test pieces are compression molded plates with dimensions of L x B x Thickness (20 cm x 15 cm x 3mm). Further, the compression molded plates are die punched into rectangular test specimen of dimensions L x B x Thickness (4 cm x 1.5 cm x 3mm). In the case of compresssion molding, injection molding was arranged to produce rectangular test specimens with dimensions L x B x Thickness (4 cm x 1.5 cm x 2mm). Examples 3 to 13 – Specific formulations used in preparation of granules Following the procedure referred to in Example 1, granules were produced using the ingredients in the table below, with the balance being made up of Virgin HDPE and PCR HDPE in a 50:50 wt% ratio. Example Mineral oil Identity of Amount of Identity of Amount of No. (carrier) peroxide peroxide branching agent branching (wt%) (wt%) agent (wt%) 3 0.1 Dicumyl 0.007 1-Dodecene 0.05 peroxide 4 0.1 Dicumyl 0.012 1-Dodecene 0.025 peroxide 5 0.1 Luperox 101 0.015 1-Dodecene 0.025 6 0.1 Luperox 101 0.015 1-Dodecene 0.025 7 0.1 Dicumyl 0.006 1-Dodecene 0 peroxide 8 0.1 Dicumyl 0.012 1-Dodecene 0 peroxide 9 0.1 Dicumyl 0.007 1-Dodecene 0.025 peroxide 10 0.1 Dicumyl 0.012 1-Dodecene 0.05 peroxide 11 0.1 Dicumyl 0.016 1-Dodecene 0.05 peroxide 12 0.1 Dicumyl 0.016 1-Dodecene 0.10 peroxide 13 0.1 Dicumyl 0.01 Diethyl maleate 0.01 peroxide 14 0.0825 Dicumyl 0.012 1-Dodecene 0.025 peroxide 15 0.124 Dicumyl 0.018 1-Dodecene 0.0373 peroxide 16 0.1 Dicumyl 0.018 1-Dodecene 0.0384 peroxide 17 0.1 Dicumyl 0.021 1-Dodecene 0.0437 peroxide 18 0.1 Dicumyl 0.009 1-Dodecene 0.01875 peroxide 19 0.1 Dicumyl 0.015 1-Dodecene 0.03125 peroxide Example 20 - Extrusion and compression molding data for PCR from a general recycle stream Granules comprising a 50:50 mixture of EBM grade virgin HDPE and PCR HDPE from a general recycle stream with a baseline ESCR (F50) 17h were selected and compression molded as described in Example 2 and ESCR and other properties were measured as described in Assessment 1. The aforementioned was compared to granules produced and compression molded from the same HDPE as described in Examples 1 and 2. Results are provided below: Impact, Example No Tensile Tensile Tensile ESCR MFI Izod, Tensile of Strength Strength Elongation Increase 190C / 21. Notched (I Modulus, formulation @ Yield @ Break @ Yield, % 6kg SO) ISO (MPa) used (MPa) (MPa) ISO (%) (kJ / m^2) None 0 20.97 21.0 13.4 7.7 57.2 866 3 182 % 22.0 20.84 14.2 7.6 57.6 874 4 176 % 20.15 19.18 14.9 7.6 49.4 891 The table shows that key mechanical properties of the HDPE resin are largely unchanged by incorporation of the formulations, but there is, advantageously, significant impact on ESCR. Example 21 - Compression molding data for food contact grade PCR The procedure of Example 20 was followed using food contact grade PCR with a baseline ESCR (F50) of 15 h. Results are provided in the table below: Example No of formulation used ESCR Improvement None 0 5 120% Food grade PCR may originate from a closed loop recycle stream and as such has greater purity but typically reduced ESCR performance owing to the grades of resin used in that marketplace. It should be appreciated that, by the inclusion of the formulation of Example 5, the ESCR of this food contact resin can be increased by 120%. Example 22 - Compression molding data for a commercially-availble low ESCR grade virgin HDPE The procedure of Example 20 was followed using a low quality virgin resin grade PCR with a baseline ESCR (F50) of 8h. Results are provided in the table below: Example No of ESCR Improvement formulation used None 0 6 112% Example 23 – Injection molding data for PCR from a general recycle stream Granules comprising a 50:50 mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) 495h. were injection molded as described in Example 2 and ESCR was measured as described in Assessment 1. Results are provided below which show that the presence of a short chain branching agent offers benefits over peroxide only formulations Examples 7 and 8. Example No of ESCR Improvement formulation used None 0 7 (Comparative) -13% 8 (Comparative) 59% 9 136% 10 112% 11 146% 12 165% Example 24 – Injection molding data for PCR with lower baseline level of ESCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 135 h. was injection molded and results are provided in the table below. Example No of ESCR Improvement formulation used None 0 10 73% Example 25 – Injection molding data for PCR with lower baseline level of ESCR and di- substituted alkene as branching agent Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 147 h. was injection molded and results are provided in the table below. Example No of ESCR Improvement formulation used None 0 13 77% Example 26-31 – Compression molding data using formulations comprising alternate chain branching agents Following the procedure described in Example 20, formulations described in the following table were prepared as described and ESCR was assessed as described in Assessment 1. Example Mineral Identity of Amount of Identity of Amount of % ESCR No. oil peroxide peroxide branching agent branching Improvement (carrier) (wt%) agent (wt%) (wt%) 26 0.1 Dicumyl 0.012 1-Hexadecene 0.033 71 peroxide 27 0.1 Dicumyl 0.012 1-Eicosene 0.041 50 peroxide 28 0.1 Dicumyl 0.0082 Methyl Oleate 0.0484 44 peroxide 29 0.1 Dicumyl 0.012 Triphenylethylene 0.05 83 peroxide 30 0.1 Dicumyl 0.0082 1,6-Hexanediol 0.0088 165 peroxide dimethacrylate 31 0.1 Dicumyl 0.012 Benzyl 0.01 31 peroxide methacrylate Example 32 – Injection molding data for flake PCR Flakes comprising a 100% post-consumer recycle with a baseline ESCR (F50) of 17 hr were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 14 141% 15 100% Example 33 – Injection molding data for flake PCR Flakes comprising a 100% post-consumer recycle with a baseline of 130 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 14 383% 15 587% Example 34 – Injection molding data for food grade PCR Granules comprising of 100% food-grade post-consumer recycle with a baseline of 64 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 14 39% 15 73% Example 35 – Injection molding data for PCR with medium baseline level of ESCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 215 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 16 116% 17 130% Example 36 – Injection molding data for PCR with a medium baseline level of ESCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 281 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 18 172% 19 206% Example 37 – Injection molding data for PCR with a medium baseline level of ESCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 127 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 17 331% 18 167% 19 227% Example 38 – Injection molding data for PCR with a low baseline level of ESCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and PCR from a general recycle stream with a baseline ESCR (F50) of 88 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 17 707% 18 136% 19 417% Example 39 – Injection molding data for food contact grade PCR Following the procedure of Example 23, a 50:50 resin mixture of EBM grade virgin HDPE and food contact grade PCR with a baseline ESCR (F50) of 88 h, were injection molded as described in example 2 and ESCR was measured as described in Assessment 1. Example No of formulation ESCR Improvement used 17 151% 18 22% 19 263% Example 40-43 – Compression molding data using formulations comprising an alternate peroxide. Granules comprising of 100% virgin EBM grade virgin HDPE with a ESCR (F50) baseline of 8 h, were selected and compression molded as described in example 2. The formulations in the following table were prepared as described and ESCR was assessed as described in Assessment 1. Example Mineral Identity Amount Identity of branching Amount of ESCR No. oil of of agent branching improvement (carrier) peroxide peroxide agent (wt%) (wt%) (wt%) 40 0 Luperox 0.015 1-Dodecene 0.03 125% 101XL45 41 0 Luperox 0.015 1-Dodecene 0.05 150% 101XL45 42 0 Luperox 0.015 1-Dodecene 0.03 200% 101XL45 43 0 Luperox 0.015 1-Dodecene 0.05 150% 101XL45 Example 44-45 - Compression molding data using formulations in food-grade PCR Granules comprising of 100% food-grade post-consumer recycle with a baseline of 11 h, were selected and compression molded as described in example 2. The formulations in the following table were prepared as described and ESCR was assessed as described in Assessment 1. Example Mineral Identity Amount Identity of branching Amount of ESCR No. oil of of agent branching improvement (carrier) peroxide peroxide agent (wt%) (wt%) (wt%) 44 0.0062 Dicumyl 0.012 1-Dodecene 0.025 200% peroxide 45 0.0062 Dicumyl 0.024 1-Dodecene 0.05 27% peroxide Example 46-47 Compression molding data using formulations in general use PCR Granules comprising of 100% general use post-consumer recycle with a baseline of 29 h, were selected and compression molded as described in example 2. The formulations in the following table were prepared as described and ESCR was assessed as described in Assessment 1.

[0002] Example Mineral Identity Amount Identity of branching Amount of ESCR No. oil of of agent branching improvement (carrier) peroxide peroxide agent (wt%) (wt%) (wt%) 46 0.0062 Dicumyl 0.012 1-Dodecene 0.025 179% peroxide 47 0.0062 Dicumyl 0.024 1-Dodecene 0.05 148% peroxide The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS 1 A formulation for treatment of a polymeric material, the formulation comprising: (i) a radical generator; and (ii) a branching agent. 2 A formulation according to claim 1, wherein said radical generator is a peroxide, a hindered amine, a nitroxide or a metal radical source. 3 A formulation according to claim 1 or clam 2, wherein said radical generator is a peroxide. 4 A formulation according to any preceding claim, wherein said radical generator is selected from dicumyl peroxide, 1,1-Di(tert.butylperoxy)cyclohexane, tert.Butylperoxybenzoate, 2,5-dimethyl-2,5-di- (tert-butylperoxy)hexane and 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate. 5 A formulation according to any preceding claim, wherein said branching agent is an olefin which includes an internal or terminal C=C double bond. 6 A formulation according to any preceding claim, wherein said branching agent includes a moiety (I); or a moiety (II). 7 A formulation according to claim 6, wherein: A) said branching agent includes a moiety which is of formulawherein: R1represents a hydrogen atom or an optionally-substituted moiety which includes carbon and hydrogen atoms only and / or includes saturated or unsaturated hydrocarbon moieties and / or is an optionally- substituted alkyl or alkenyl group and / or includes one or more functional groups selected from ether, nitro, ester, amide and hydroxy; and R2represents a hydrogen atom or an optionally-substituted moiety which includes carbon and hydrogen atoms only and / or includes saturated or unsaturated hydrocarbon moieties and / or is an optionally- substituted alkyl or alkenyl group and / or includes one or more functional groups selected from ether, nitro, ester, amide and hydroxy; or R1and R2together define an optionally-substituted cyclic structure; or B) said branching agent includes a moiety which is of formulawherein: R3and R4independently represent optionally-substituted alkyl or aryl groups, or represent an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV; and R10represents a hydrogen atom or an optionally-substituted alkyl or aryl groups, or represents an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV. 8 A formulation according to claim 7, wherein, when R10represents a hydrogen atom, R3and R4independently represent optionally-substituted alkyl groups, for example optionally-substituted C1-C10 alkyl groups, or represents an ester group bonded by its carbonyl carbon to the alkenyl carbon atom of moiety IV.9 A formulation according to any preceding claim, wherein said branching agent includes 4 to 100, preferably 6 to 50, more preferably 10 to 30, carbon atoms; and / or said branching agent has a melting point of greater than 10oC; and said melting point is less than 300oC or less than 200oC. 10 A formulation according to any preceding claim, wherein said branching agent is an α-olefin, for example, 1-dodecene; or said branching agent is selected from 4-Vinylanisole, α-Methylstyrene, 3- Nitrostyrene, Benzyl methacrylate, 1,1-Diphenylethylene, Camphene, Diacetone acrylamide, 1,9- decdiene, Vinylcyclohexene and Eugenol. 11 A formulation according to any preceding claim, wherein said branching agent includes a moiety of formulaIV, wherein R3and R4are independently selected from:(VI); and (VII)wherein the * carbon indicates the position of bonding to the double bond of moiety IV and n, m and q are integers. 12 A formulation according to any preceding claim, wherein said branching agent is selected from 1- Dodecene, Diethylmaleate, 1-Hexadecene, 1-Eicosene, Methyl Oleate, Triphenylethylene, 1,6- Hexanediol dimethacrylate and Benzyl methacrylate.13 A formulation according to any preceding claim, wherein said formulation includes a carrier. 14 A formulation according to claim 13, wherein said radical generator is fully dissolved in the carrier and / or said branching agent is fully dissolved in the carrier, wherein, optionally, said carrier comprises a hydrocarbon-containing liquid. 15 A formulation according to any of claims 1 to 13, wherein said formulation is a solid which, optionally, is selected from a polyolefin, a Styrenic block polymer, Ethylene-vinyl acetate (EVA) or Ethylene Propylene Rubber (EPR). 16 A formulation according to any preceding claim, wherein said formulation includes: 1 to 10 wt% of said radical generator; 1 to 50 wt% of said branching agent; 49 to 98 wt% of said carrier. 17 A formulation according to any of claims 13 to 16, wherein: a sum of the wt% of all radical generators in the formulation is in the range 0.01 to 2.0 wt%; a sum of the wt% of all branching agents in the formulation is in the range 0.01 to 2.0 wt%; and a sum of the wt% of all carriers in said formulation is in the range 50 to 99.9 wt%. 18 A formulation according to any preceding claim, wherein, in said formulation: a ratio defined as the wt% of said radical generator divided by the wt% of said branching agent is in the range 1:1 to 1:100, for example in the range 1:1 to 1:10; and / or a ratio defined as the sum of the wt% of all radical generators divided by the sum of the wt% of all branching agents is in the range 1:1 to 1:100, for example in the range 1:1 to 1:10.19 A formulation according to any preceding claim, wherein said formulation includes a radical mediator / polymerization inhibitor able to accept or donate a radical and prevent pre-reaction of monomers. 20 A mixture comprising: (a) a polymeric material; (b) a radical generator or a residue thereof; (c) a branching agent or a residue thereof; and, optionally (but preferably) (d) a carrier. 21 A mixture according to claim 20, wherein the mixture comprises said polymeric material and the formulation of any of claims 1 to 19. 22 A mixture according to claim 20 or claim 21, wherein said polymeric material comprises one or more polyolefins. 23 A mixture according to any of claims 20 to 22, wherein said mixture comprises at least two polyolefins from different sources and / or which have different identities and / or properties. 24 A mixture according to any of claims 20 to 23, wherein said polymeric material comprises polyethylene. 25 A mixture according to any of claims 20 to 24, wherein said polymeric material comprises recycled material, for example PCR or PIR. 26 A mixture according to any of claims 20 to 25, wherein said polymeric material comprises at least 25wt% virgin polymer. 27 A mixture according to any of claims 20 to 26, wherein said mixture is in a solid form, for example in the form of pellets or granules. 28 A product of the treatment of: (a) a polymeric material; with(b) a radical generator; (c) a branching agent; and, optionally (but preferably) (d) a carrier. 29 A product according to claim 28, wherein the product is produced by the treatment (eg melt- processing and / or reaction) of said polymeric material with the formulation of any of claims 1 to 19 and said product is in the form of granules or pellets or an article, for example a container or extruded sheet or film. 30 A method of improving mechanical properties of a polymeric material which, optionally, includes recycled polymeric material, the method comprising: (i) selecting a first mass of polymeric material, wherein said first mass includes a first polymeric material and, optionally, recycled polymeric material; (ii) contacting said first mass with said formulation of any of claims 1 to 19 and / or with a mixture of any of claims 20 to 27; and (iii) melt-processing the combination produced in step (ii). 31 A method according to claim 30, wherein said first polymeric material comprises a polyolefin for example polyethylene and / or polypropylene and comprises at least 80 wt% of virgin polyolefin. 32 A method according to claim 30 or claim 31, wherein a polymeric material produced in the method includes 50 to 100wt% of said first polymeric material and 0 to 50wt% of recycled polymeric material; and, optionally, said polymeric material produced in the method is in the form of granules or pellets. 33 A method according to any of claims 30 to 32, wherein said method is a method of improving environmental stress cracking (ESCR) of said polymeric material. 34 A molded article, pellets or granules which comprise a polymeric material and a trace amount of one or more of the following: a radical generator or a residue thereof as described in any preceding claim; a branching agent or a residue thereof as described in any preceding claim; and / or a carrier or a residue thereof as described in any preceding claim; and / orwherein said polymeric material includes a part of a branching agent as herein described.

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