Polyhydroxyalkanoate polymeric product

Abstract

The present invention relates to a method for the preparation of a polymeric product comprising a first polyhydroxyalkanoate polymer and at least a second polymer, said method comprising : a) a step of forming a mixture comprising a first poly 3-hydroxybutyrate ( PHB) polymer, at least a second polymer and at least one oxidising agent and a plasticizer, and b) a step of heating said mixture to a temperature between 200 and 230 °C, to form said polymeric product.

Description

[0001] POLYHYDROXYALKANOATE POLYMERIC PRODUCT

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from Italian Patent Application No . 102024000005116 filed on March 7 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The present invention relates to a method for the preparation of a polymeric product based on a polyhydroxyalkanoate .

[0006] Context

[0007] It is now imposs ible to ignore the growing demand to replace plastics originating from non-renewable fossil and petrochemical sources with new innovative materials within the supply chain of plastic consumer goods .

[0008] Plastics , which are used daily for several applications , in addition to being produced using unsustainable and gradually deteriorating raw materials , are becoming increasingly di f ficult and complex to manage at the end of their use . Just think of consumer goods that are used on a daily basis , such as food packaging, disposable plastic utensils such as forks , plates and cups , or still plastic bags or film for packaging goods . All the examples j ust mentioned perfectly ful fil their designated functions , although they are then immediately thrown away as soon as their use has been ful filled . This vicious circle of "mass production - single-use - discard" has become an automatism of modern society that , while undoubtedly being beneficial and comfortable in the short term, has disastrous side ef fects from an environmental perspective due to the long degradation times of conventional plastic, sometimes over 1000 years . Over the past 60 years , global plastic production has grown from about 0 . 5 million tons in 1950 to more than 260 million tons today, and it continues to increase steadily every year .

[0009] The family of bioplastics known by the name of polyhydroxyalkanoates ( PHAs ) appears to be an excel lent and viable choice for a sustainable future with reduced CO2 emissions . Precisely within this class of polymers is polyhydroxybutyrate ( PHB ) , a natural biodegradable thermoplastic polyester that is considered a potential and viable substitute for synthetic polymers in many applications , by virtue of some of its excellent qualities .

[0010] PHB is produced naturally as an energy stock material within microorganisms and bacteria, from which it is subsequently extracted, processed and produced, typically in the form of pellets or granules .

[0011] In the following text , the term polyhydroxybutyrate ( PHB ) refers to a homopolymer of poly-3-hydroxybutyrate .

[0012] This type of production makes it a biological and biodegradable plastic, therefore able to perfectly meet the new demands of the market .

[0013] The main disadvantages linked to its use are due to its poor thermal stability and to its high fragility, which in many cases limit its potential use , especially in industrial applications or in the production of mass goods .

[0014] In order to overcome these di sadvantages , various strategies can be employed, such as the addition of plastici zers , heat treatments or mixing with other polymers .

[0015] Therefore , aim o f the present invention is to provide a new method for the production of a polymeric product based on polyhydroxybutyrate that has better characteristics in terms of elasticity and ductility, while retaining its benefits associated with its productive sustainability and biodegradability .

[0016] Summary

[0017] According to the present invention there is provided a method for the production of a polymeric product as defined in claim 1 .

[0018] Brief Description of the Drawings

[0019] To better understand the present invention preferred embodiments thereof will be now described, for merely exemplary and non-limiting purposes , with reference to the appended drawings , wherein :

[0020] - Figure 1 shows the mechanical data of a polymeric product obtained starting from a mixture of 30% PHB and 70% polylactic acid ( PLA) on the total of the polymer component , in the presence o f 1 % dicumyl peroxide ( DCP ) and 15% tri-n- butyl citrate ( TBC ) on the total of the mixture as a function of the process temperature : A) data relating to the trend of the strain at break when the temperature varies ; B ) data relating to the elastic modulus when the temperature varies .

[0021] Figure 2 shows the rheological behaviour of polyhydroxybutyrate without further additives and treatments ;

[0022] Figure 3 shows the rheological behaviour of polybutyrate-co-adipate terephthalate without further additives and treatments ; - Figure 4 shows the rheological behaviour of polylactic acid without further additives and treatments ;

[0023] - Figure 5 shows the rheological behaviour of a polymeric product based on 30% polyhydroxybutyrate and 70% polylactic acid whose mixture is treated at 200 °C without the addition of further additives and treatments ;

[0024] Figure 6 shows the rheological behaviour of the polymeric product of the invention based on 30% polyhydroxybutyrate and 70% polylactic acid with the addition of 1 % dicumyl peroxide , produced at 200 ° C ;

[0025] Figure 7 shows the rheological behaviour of the polymeric product of the invention based on 30% polyhydroxybutyrate and 70% polylactic acid with the addition of 1 % dicumyl peroxide , produced at 230 ° C .

[0026] Figure 8 shows the mechanical behaviour of the polymeric product according to example 1 .

[0027] - Figure 9 shows the mechanical behaviour of the polymeric product according to example 2 .

[0028] - Figure 10 shows the mechanical behaviour of the polymeric product according to example 3 .

[0029] - Figure 11 shows the mechanical behaviour of the polymeric product according to example 4 .

[0030] - Figure 12 shows the mechanical behaviour of the polymeric product according to example 5 .

[0031] Description of Embodiments

[0032] An embodiment of the present invention is a method for the production of a polymeric product comprising polyhydroxybutyrate ( PHB ) and at least a second polymer, said method comprising : a ) a step of forming a mixture comprising polyhydroxybutyrate ( PHB ) , at least a second polymer and at least one oxidising agent and a plastici zer, and b ) a step of heating said mixture to a temperature between 200 and 230 ° C, to form said polymeric product wherein said oxidising agent is present in a proportion of between 1 and 3% by weight on the total weight of the polymeric product .

[0033] Aim of this process is to activate , by means of a controlled thermal degradation technique , along the main linear chain of the PHB of the reactive sites to which it is possible to bind secondary chains of other biopolymers so as to obtain a branched copolymer . Obtaining a branched structure leads to a greater ductility and the consequent reduction in the fragility of the copolymer compared to the starting material .

[0034] Advantageously, the copolymers obtained with the method of the present invention have a better strain at break and an elastic modulus than the starting polyhydroxyalkanoate .

[0035] The mechanical data of a polymeric product according to the invention when the process temperature varies are shown in Figures 1A and IB . It appears an increasing linear trend in the case of the maximum strain at break sr(panel A) , and a decreasing linear trend with regard to the elastic modulus E (panel B ) therefore , as the process temperature increases , there is an increase in the maximum strain at break while the elastic modulus decreases .

[0036] The data of the curve at point 230 ° C corresponds to the data of example 2 ( PHB-PLA-DCP-TBC produced at 230 ° C ) . The polymeric product of the invention also shows a different rheological behaviour with respect to that of the starting polymers.

[0037] The first data to highlight, observing Figures 2, 3 and 4, is the difference between the rheological behaviour of PHB, PBAT and PLA.

[0038] In particular, in the case of PHB (Figure 2) , we can note how the viscosity initially decreases as the material melts, but once the temperature of 220°C-230°C is reached, it is possible to observe how the latter rises suddenly due to thermal degradation and branching phenomena that begin to take place. What has been said, however, is not applicable in the case of PBAT and PLA (Figure 3, Figure 4) , where it is only possible to appreciate a decrease in viscosity in relation to the increase in temperature and the dissolution of the material (the material flows and the viscosity decreases) , and therefore no phenomenon of branching and / or controlled degradation.

[0039] Interestingly, even in the case of the PHB / PLA formulation in Figure 5 (no additives, no peroxides) , no increase in viscosity is observed once the critical temperature is reached. On the other hand, taking under examination the same formulation but with the addition of peroxide (Figure 6) , we can note how the behaviour is different .

[0040] Once again, as in the case of pure PHB, we note how viscosity tends to increase once the controlled thermal degradation temperature is reached and exceeded. This behaviour can be translated into proof of occurred branching / cross-linking of the formulation. Finally, the same test on the same formulation but produced at higher temperature ( Figure 7 ) shows a further and more signi ficant increase in viscosity : the production process at high temperatures can favour a branched and / or cross-linked structure .

[0041] First polyhydroxybutyrate ( PHB ) polymer

[0042] In particular, PHB is characterised by a strain at break ( indicated with the Greek letter sr) and by an elastic modulus (measurement of the sti f fness of the material , indicated with letter E ) , measured by standard method following the international standard ASTM D- 638 for plastic materials ( " Standard Test Method for Tensile Properties of Plastics " ) , of :

[0043] Sr = 1 %

[0044] E = 2100 MPa and its copolymers , obtained with the method of the invention, reach values of strain at break and elastic modulus higher than 1000 times in the case of deformations , and about 100 times lower in the case of modulus ( in the best compositions ) .

[0045] In a further preferred embodiment , the polyhydroxybutyrate ( PHB ) may be present in the mixture to form the polymeric product of the invention in a percentage of between 5% and 90% by weight on the total weight of said mixture , preferably between 15% and 70 % , more preferably between 15% and 30% , on the total weight of said mixture .

[0046] Second polymer

[0047] In a preferred embodiment in the method according to the present invention the second polymer is selected from the group consisting of polylactic acid, polybutylene-co- adipate terephthalate , polycaprolactone, polybutyratesuccinate , polypropylene carbonate , natural rubber, epoxidi zed natural rubber, polybutadiene , polyisoprene , nitrile-butadiene copolymer rubber, butadiene-vinylpyridine copolymer rubber, styrene-butadiene copolymer rubber, neoprene , silicone , rubbers of the polyethylene elastomer family such as EPDM butadiene-ethylene-propylene rubbers or Hypalon type chlorosul fonated polyethylene , rubbers of the fluorolefin elastomer family such as tetrafluoroethylene and perfluoropropene and vinylidene fluoride , latex, cellulosederived bioplastics such as MaterBi type functionalised starch, plasticised starch such as corn starch plasticised with glycerol , corn starch plasticised with ethanolamine, corn starch plasticised with sorbitol , corn starch plasticised with sorbitol and glycerol , corn starch plasticised with urea, corn starch plasticised with urea and ethanolamine , corn starch plasticised with thymol , corn starch plasticised with glycerol and thymol , corn starch plasticised with l-ethyl-3-methylimidazolium acetate and water, potato starch plasticised with glycerol , potato starch plasticised with ethanolamine , potato starch plasticised with sorbitol , potato starch plasticised with sorbitol and glycerol , potato starch plasticised with urea, potato starch plasticised with urea and ethanolamine , potato starch plasticised with thymol , potato starch plasticised with glycerol and thymol , potato starch plasticised with 1- ethyl-3-methylimidazolium acetate and water, wheat starch plasticised with glycerol , wheat starch plasticised with 1- ethyl-3-methylimidazolium and water, rice starch plasticised with glycerol , rice starch plasticised with sorbitol , mango kernel starch plasticised with glycerol, mango kernel starch plasticised with sorbitol, cellulose cinnamate, cellulose acetate, lignin, cellulose, hemicellulose, LATI type hemp plastic or HempPlastic, coffee silverskin and conventional polymers such as polyesters, polyethers, polyamides, such as polyethylene, polystyrene, polyethylene terephthalate, polypropylene, acrylonitrile-butadiene-styrene, ethylene vinyl acetate, compact rigid polyurethane, compact elastic polyurethane, expanded polyurethane, thermoplastic polyurethane, polycarbonate, polybutylene terephthalate, polysulfone, polyvinyl alcohol and lactic acid oligomers. Preferably the second polymer is selected from the group consisting of polylactic acid, polybutylene adipate terephthalate, polycaprolactone, polybutyrate-succinate, natural rubber, latex and polypropylene carbonate.

[0048] In a preferred embodiment the second polymer may be present in the mixture to form the copolymer of the present invention in a percentage of between 10% and 95% by weight on the total weight of said mixture, preferably between 30% and 85%, more preferably between 70% and 85% by weight on the total weight of said mixture.

[0049] Oxidising agent

[0050] In a preferred embodiment the oxidising agent is selected from the group consisting of a peroxide, a plasticizer, an inorganic base and an inorganic oxide.

[0051] In particular, peroxides, once thermally activated, dissociate into the so-called free radicals, unstable molecules characterised by high energies and by an unpaired electron. When the radical arrives near the linear chain of PHA it can break a CH bond, tearing the H atom from the carbon and thus leaving a reactive site C* on the chain. This site becomes the point where the secondary chains of the selected biopolymer are linked, repeating the process and thus giving rise to the branched structure.

[0052] Therefore, the combined effect of the high temperature together with the addition of peroxide favours the formation of such architectures, solving the problem of the fragility of PHA but preserving its properties.

[0053] In a preferred embodiment the peroxidising agent is a peroxide selected from the group consisting of dicumyl peroxide, dibenzoyl peroxide, organic dialkyl peroxide type

[0054] 2.5-dimethyl-2 , 5-di ( t-butylperoxide ) hexane, 2,5-bis (t- butylperoxide ) -2, 5-dimethylhexane, tert-butylperoxide-2- ethyl -hexyl -carbonate t er t- amylperoxide -2 - ethyl hexyl - carbonate, n-butyl-4, 4-di- ( tert-butylperoxide ) valerate,

[0055] 2.5-dimethyl-di (t-butylperoxide) hexine-3, di-t-butyl peroxide, di-t-amyl peroxide, t-amyl peroxide-2-ethylhexyl carbonate (TAEC) , t-butyl cumyl peroxide, n-butyl-4 , 4-bis ( t- butylperoxide ) valerate, 1, 1-di (t-butylperoxide) -3, 3, 5- trimethylcyclohexane, 1, 1-bis (t-butylperoxide) -3, 3, 5- trimethylcyclohexane (CPK) , l,l-di (t- butylperoxide ) cyclohexane, 1, 1-di ( t-amylperoxide ) - cyclohexane, 2, 2-di (t-butylperoxide) butane, ethyl-3 , 3-di ( t- butylperoxide ) butyrate, 2, 2-di (t-amylperoxide) propane, ethyl-3, 3-di (t-amylperoxide) butyrate, t-butyl peroxideacetate, t-amyl peroxide acetate, t-butyl peroxide benzoate (TBPB) , t-amyl peroxide benzoate, di-t-butyl peroxide phthalate, bis-dimethyl benzyl peroxide, lauroyl peroxide, dodecanoyl peroxide, tert-butyl peroxybenzoate, tert-butyl perbenzoate and dimethylbenzoyl peroxide. Preferably said peroxide is dicumyl peroxide. In a preferred embodiment said peroxide is added to the mixture in a range of between 1% and 3%, with respect to the total weight of the mixture.

[0056] In a further preferred embodiment the oxidising agent is a hydroxide or an oxide selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, magnesium hydroxide, copper hydroxide, iron hydroxide, zinc hydroxide, aluminium hydroxide, rubidium hydroxide, potassium hydroxide, caesium hydroxide, strontium hydroxide, tetramethylammonium hydroxide, beryllium hydroxide, arsenic hydroxide, boron hydroxide, chromium hydroxide, cobalt hydroxide, gallium hydroxide, gold hydroxide, indium hydroxide, iridium hydroxide, lead hydroxide, manganese hydroxide, mercury hydroxide, molybdenum hydroxide, nickel hydroxide, osmium hydroxide, palladium hydroxide, platinum hydroxide, silver hydroxide, thallium hydroxide, tungsten hydroxide, vanadium hydroxide, yttrium hydroxide, zirconium hydroxide, titanium hydroxide, tin hydroxide, tantalum hydroxide, ruthenium hydroxide, rhodium hydroxide, niobium hydroxide, neodymium hydroxide, lanthanum hydroxide, cadmium hydroxide, bismuth hydroxide, ammonium hydroxide, sodium oxide, potassium oxide, calcium oxide, barium oxide, lithium oxide, magnesium oxide, copper oxide, iron oxide, zinc oxide, aluminium oxide, rubidium oxide, potassium oxide, caesium oxide, strontium oxide, tetramethylammonium oxide, beryllium oxide, arsenic oxide, boron oxide, chromium oxide, cobalt oxide, gallium oxide, gold oxide, indium oxide, iridium oxide, lead oxide, manganese oxide, mercury oxide, molybdenum oxide, nickel oxide, osmium oxide, palladium oxide, platinum oxide, silver oxide, thallium oxide, tungsten oxide, vanadium oxide, yttrium oxide, zirconium oxide, titanium oxide, tin oxide, tantalum oxide, ruthenium oxide, rhodium oxide, niobium oxide, neodymium oxide, lanthanum oxide, cadmium oxide, bismuth oxide, acetone (or dimethylketone) , ammonia (nitrogen trihydride) , pyridine, guanidine, n-butyllithium, lithium di-isopropylamide, lithium di-ethylamide, sodium ammonide, sodium hydride, lithium bis (trimethylsilyl) amide, potassium sodium carbonate, potassium cyanide, diethylamine, ethylamine, dimethylamine, methylamine, trimethylamine, hydrazine, morphine, nicotine, oxydrylamine, aniline, and urea .

[0057] Preferably said oxidising agent is a hydroxide or oxide is selected from the group consisting of magnesium hydroxide or calcium oxide.

[0058] In one embodiment said oxidising agent is present in the mixture in percentages from 0.1% to 5% with respect to the total weight of the mixture.

[0059] In a preferred embodiment the oxidising agent is a plasticizer selected from the group consisting of tri-n- butyl citrate, tributyrin, glycerol, polyglycerol, glycerol triacetate, glycerol tributyrate, chitosan, cellulose nanocrystals, polyethylene glycol, polypropylene glycol, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, butyryl triesyl citrate, salicylic acid, acetyl salicylic acid, ethyl salicylic acid, hexyl salicylic acid, decyl salicylic acid, 2-butyloctyl salicylic acid, ethyl acetylsalicylic acid, hexyl acetylsalicylic acid, decyl acetylsalicylic acid, arylpropionic acid, phthalic acid, triglycidyl isocyanurate, propanediol, 1 , 4-propanediol , 1,2- butanediol, 1 , 3-butanediol , pentanediol, 1 , 5-hexanediol , 1 , 6-hexanediol , 1,3-bis ( t-butylperoxysopropyl ) benzene [ 1 , 3-Bis-butylperoxysopropyl ) benzene] , 1 , 2 , 6-hexanetriol , 1 , 3 , 5-hexanetriol , neopentyl glycol, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, sorbitol diethoxylate, sorbitol hexaethoxylate, sorbitol dipropoxylate, aminosorbitol, trihydroxymethylaminomethanebutanediol, neopentyl glycol, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, butyl glucoside, diisononyl adipate, propionate, orthocresol, lactone monoethoxylate, mannitol monoacetate, mannitol monoethoxylate, butyl glucoside, glucose monoethoxylate, a-methyl glucoside, carboxymethyl tallow sodium salt, polyglycerol monoethoxylate, formamide, N-me thy 1 formamide, 1 , 3 -bis ( 4 , 5-dihydro-2-oxazolyl ) benzene, 1 , 4 -bis ( 4 , 5-dihydro-2-oxazolyl ) benzene, 2, 2 -bis (4,5- dihydro-2-oxazolyl ) benzene triallyl isocyanurate, triallyl trimester, triallyl trimesate, trimethylpropane triacrylate, triallyl cyanurate, pentaerythrole triacrylate, 1,1,1- trimethyl olethanetrinitrate, 1,2,4-butane triol trinitrate, 1 , 3-biscarbazoyl propane, propane 1,2 diol, propane 1,3 diol, 1 , 3-diphenylpropane-l , 3-dionate, 2,2-bis (p- hydroxyphenyl ) propane diglycidyl ether; nitrogen compounds such as phenylurea, N, N ' -diphenylthiourea and 2- phenylindole, 1 , 4-cyclohexane dimethanol dibenzoate, abietic acid, adipic acid, alkyl sulfonate, azelaic acid, benzoates, dibenzoates, benzoyl acid, chloroparaffin, stearyl citrate, ethyl citrate, butyl citrate, hexyl citrate, polyglycid nitrate, bisdinitropropyl , dimethyl methylenedinitramine, di-2-ethylhexylphthalate, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene, tetrapropylene glycol, glutaric acid, paraffin, isoparaffin, cyclohexane, decalin, naphthalene, dibenzothiophene, carbazole, 2 , 2 , 4-trimethyl-l , 3-pentadiol diisobutyrate, sucrose diacetate hexisobutyrate, pentaerythrole, phosphoric acid, phthalic acid, isoprene, isobutylene, methyl vinylidene, ricinoleic acid, p-toluene sulphonamide, n-butylbenzene sulphonamide, trimellytate, pyromellytate, dicyclohexylbiphenyl, calcium stearate, diurethane, 2- ( 2 ' -hydroxyphenyl ) benzotriazole, such as 2- ( 2 ' -hydroxy-5 ' -methylphenyl ) -benzotriazole 2- hydroxybenzophenone, an unsubstituted or substituted benzoic acid ester, such as 4-tert-butylphenyl salicylate, phenyl salicylate, acrylate, nickel compound, oxalamide such as 4 , 4 ' -dioctyloxyoxanilide, 2 , 2 ' -dioctyloxy-5, 5'-ditert- butyleusanilide, 2- (2-hydroxyphenyl) -1, 3, 5-triazine, such as 2, 4, 6-tris (2-hydroxy-4-octyloxyphenyl) -1, 3, 5-triazine 2- ( 2-hydroxy-4-octyloxy ) phenyl ) -4 , 6-bis (2, 4- dimethylphenyl) -1, 3, 5-triazine and sterically hindered amines such as bis (2, 2, 6, 6-tetramethylpiperidin-4-yl sebacate) ) , and bis (2, 2, 6, 6-tetramethylpiperidin-4-yl) succinate. Preferably said plasticizer is tri-n-butyl citrate .

[0060] Preferably said plasticizer is contained in the mixture in percentages of 5%-20% with respect to the total weight of the mixture . In one embodiment, the mixture comprises an oxidising agent and a plasticizer, preferably a peroxide and a plasticizer, more preferably dicumyl peroxide and tri-n- butyl citrate .

[0061] In the following, the present invention will be shown by means of some examples , which are not intended to be considered limiting of the scope of the invention .

[0062] Examples

[0063] Example 1

[0064] Preparation of a copolymer of PHB and polylactic acid .

[0065] A mixture was produced with PHB and PLA (polylactic acid) in proportions of 30% and 70% , respectively, to which 15% with respect to the total weight of the mixture of tri- n-butyl citrate as bioplastici zer was added . Taking advantage of the high temperatures , a partial degradation of PHB was induced .

[0066] To measure the mechanical properties shown in Figure 8 , a universal test machine was used by performing a mono-axial tensile test following the ASTM D- 638 standard for plastic materials .

[0067] Process parameters :

[0068] • T = 200 ° C

[0069] • Degradation time = 5- 10 '

[0070] Results :

[0071] • sr= 218 %

[0072] • E = 383 Mpa

[0073] Example 2

[0074] Preparation of a copolymer of PHB and polylactic acid

[0075] A mixture was produced with PHB and PLA (polylactic acid) in proportions of 30% and 70% , respectively, to which 1 % with respect to the total weight of the mixture of the peroxide dicumyl peroxide and 15% with respect to the total weight of the mixture of tri-n-butyl citrate as bioplasticizer were added.

[0076] Taking advantage of the high temperatures, a partial degradation of PHB was induced, to which the further effect of peroxide to produce a copolymer with a branched structure and high ductility is associated.

[0077] To measure the mechanical properties shown in Figure 9, a universal test machine was used by performing a mono-axial tensile test following the ASTM D-638 standard for plastic materials .

[0078] Process parameters:

[0079] • T = 230 °C

[0080] • Degradation time = 5-10'

[0081] Results :

[0082] • sr= 277%

[0083] • E = 217 MPa

[0084] Example 3

[0085] Preparation of a copolymer of PHB and poly butyrate-co- adipate terephthalate

[0086] A mixture was produced with PHB and PBAT (poly butyrate- co-adipate terephthalate) in proportions, of 30% and 70%, respectively, to which 1% with respect to the total weight of the mixture of the peroxide dicumyl peroxide was added. Also in this case, PHB underwent thermal degradation.

[0087] To measure the mechanical properties shown in Figure 10, a universal test machine was used by performing a mono- axial tensile test following the ASTM D-638 standard for plastic materials.

[0088] Process parameters:

[0089] • T = 230 °C

[0090] • Degradation time = 5-10' Results :

[0091] £ 100%

[0092] • E = 180 MPa

[0093] Example 4

[0094] Preparation of a copolymer of PHB and poly butyrate-co- adipate terephthalate .

[0095] A mixture was produced with PHB and PBAT (poly butyrate- co-adipate terephthalate ) in proportions , of 30% and 70% , respectively, to which 15% with respect to the total weight of the mixture of tri-n-butyl citrate as bioplastici zer was added . Also in this case the PHB has undergone degradation .

[0096] To measure the mechanical properties shown in Figure 11 , a universal test machine was used by performing a mono- axial tensile test following the ASTM D- 638 standard for plastic materials .

[0097] Process parameters :

[0098] • T = 200 ° C

[0099] • Degradation time = 5- 10 '

[0100] Results :

[0101] • £r= 786%

[0102] • E = 25 MPa

[0103] Example 5

[0104] Preparation of a copolymer of PHB and poly butyrate-co- adipate terephthalate

[0105] A mixture was produced with PHB and PBAT (poly butyrate- co-adipate terephthalate ) in proportions , of 25% and 75% , respectively, to which 20% with respect to the total weight of the mixture of tri-n-butyl citrate as bioplastici zer and 1 % with respect to the total weight of the mixture of magnesium hydroxide as oxidising agent were added . Also in this case the PHB has undergone degradation .

[0106] To measure the mechanical properties shown in Figure 12 , a universal test machine was used by performing a mono- axial tensile test following the ASTM D- 638 standard for plastic materials .

[0107] Process parameters :

[0108] • T = 230 ° C

[0109] • Degradation time = 5- 10 '

[0110] Results : • £r = 905%

[0111] • E = 35 MPa

[0112] From the above examples it is evident how the new mixtures produced by means of the controlled degradation process of the invention can find applications in various fields , overcoming the limitations imposed by conventional PHB and being usable for the production of consumer goods .

Claims

CLAIMS1 . A method for the preparation of a polymeric product comprising polyhydroxybutyrate ( PHB ) and at least a second polymer, said method comprising : a ) a step of forming a mixture comprising polyhydroxybutyrate , at least a second polymer and at least one oxidising agent and a plastici zer, and b ) a step of heating said mixture to a temperature between 200 and 230 ° C, to form said polymeric product , said second polymer being selected from the group consisting of polylactic acid, polybutylene-co-adipate terephthalate , polycaprolactone , polybutyrate-succinate , polypropylene carbonate , natural rubber, epoxidi zed natural rubber, polybutadiene , polyisoprene , nitrile-butadiene copolymer rubber, butadiene-vinylpyridine copolymer rubber, styrenebutadiene copolymer rubber, neoprene , silicone , EPDM butadiene-ethylene-propylene rubbers , chlorosulphonated polyethylene , tetrafluoroethylene , perfluoropropene , vinylidene fluoride , latex, functionalised starch, corn starch plasticised with glycerol , corn starch plasticised with ethanolamine , corn starch plasticised with sorbitol , corn starch plasticised with sorbitol and glycerol , corn starch plasticised with urea, corn starch plasticised with urea and ethanolamine , corn starch plasticised with thymol , corn starch plasticised with glycerol and thymol , corn starch plasticised with l-ethyl-3-methylimidazolium acetate and water, potato starch plasticised with glycerol , potato starch plasticised with ethanolamine , potato starch plasticised with sorbitol , potato starch plasticised with sorbitol and glycerol , potato starch plasticised with urea,potato starch plasticised with urea and ethanolamine, potato starch plasticised with thymol, potato starch plasticised with glycerol and thymol, potato starch plasticised with 1- ethyl-3-methylimidazolium acetate and water, wheat starch plasticised with glycerol, wheat starch plasticised with 1- ethyl-3-methylimidazolium and water, rice starch plasticised with glycerol, rice starch plasticised with sorbitol, mango kernel starch plasticised with glycerol, mango kernel starch plasticised with sorbitol, cellulose cinnamate, cellulose acetate, lignin, cellulose, hemicellulose, hemp plastic, coffee silverskin, polyethylene, polystyrene, polyethylene terephthalate, polypropylene, acrylonitrile-butadiene- styrene, ethylene vinyl acetate, compact rigid polyurethane, compact elastic polyurethane, expanded polyurethane, thermoplastic polyurethane, polycarbonate, polybutylene terephthalate, polysulfone, polyvinyl alcohol and lactic acid oligomers, wherein said oxidising agent is present in a proportion of between 1 and 3% by weight on the total weight of the polymeric product.

2. Method according to claim 1, characterised in that said second polymer is selected from the group consisting of polylactic acid, polybutylene adipate terephthalate, polycaprolactone, polybutyrate-succinate, natural rubber, latex and polypropylene carbonate.

3. Method according to claim 1, characterised in that said oxidising agent is selected from the group consisting of peroxide, an inorganic base and an inorganic oxide.

4. Method according to claim 3, characterised in that said peroxide is selected from the group consisting ofdicumyl peroxide, dibenzoyl peroxide, organic dialkyl peroxide type 2 , 5-dimethyl-2 , 5-di ( t-butylperoxide ) hexane, 2, 5-bis (t-butylperoxide) -2, 5-dimethylhexane, tert- butylperoxide-2-ethyl-hexyl-carbonate, ter t-amylperoxide- 2- ethylhexyl-carbonate, n-butyl-4, 4-di- (tertbutylperoxide) valerate, 2, 5-dimethyl-di (t- butylperoxide ) hexine-3 , di-t-butyl peroxide, di-t-amyl peroxide, t-amyl peroxide-2-ethylhexyl carbonate (TAEC) , t- butyl cumyl peroxide, n-butyl-4 , 4-bis ( t- butylperoxide ) valerate, 1, 1-di (t-butylperoxide) -3, 3, 5- trimethylcyclohexane, 1, 1-bis (t-butylperoxide) -3, 3, 5- trimethylcyclohexane (CPK) , l,l-di (t- butylperoxide ) cyclohexane, 1, 1-di ( t-amylperoxide ) - cyclohexane, 2, 2-di (t-butylperoxide) butane, ethyl-3 , 3-di ( t- butylperoxide ) butyrate, 2, 2-di (t-amylperoxide) propane, ethyl-3, 3-di (t-amylperoxide) butyrate, t-butyl peroxideacetate, t-amyl peroxide acetate, t-butyl peroxide benzoate (TBPB) , t-amyl peroxide benzoate, di-t-butyl-diperoxide phthalate, bis-dimethyl benzyl peroxide, lauroyl peroxide, dodecanoyl peroxide, tert-butyl peroxybenzoate, tert-butyl perbenzoate and dimethylbenzoyl peroxide.

5. Method according to claim 4, characterised in that said peroxide is dicumyl peroxide.

6. Method according to claim 3, characterised in that said oxidising agent is a hydroxide or an oxide selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, magnesium hydroxide, copper hydroxide, iron hydroxide, zinc hydroxide, aluminium hydroxide, rubidium hydroxide, potassium hydroxide, caesium hydroxide, strontiumhydroxide, tetramethylammonium hydroxide, beryllium hydroxide, arsenic hydroxide, boron hydroxide, chromium hydroxide, cobalt hydroxide, gallium hydroxide, gold hydroxide, indium hydroxide, iridium hydroxide, lead hydroxide, manganese hydroxide, mercury hydroxide, molybdenum hydroxide, nickel hydroxide, osmium hydroxide, palladium hydroxide, platinum hydroxide, silver hydroxide, thallium hydroxide, tungsten hydroxide, vanadium hydroxide, yttrium hydroxide, zirconium hydroxide, titanium hydroxide, tin hydroxide, tantalum hydroxide, ruthenium hydroxide, rhodium hydroxide, niobium hydroxide, neodymium hydroxide, lanthanum hydroxide, cadmium hydroxide, bismuth hydroxide, ammonium hydroxide, sodium oxide, potassium oxide, calcium oxide, barium oxide, lithium oxide, magnesium oxide, copper oxide, iron oxide, zinc oxide, aluminium oxide, rubidium oxide, potassium oxide, caesium oxide, strontium oxide, tetramethylammonium oxide, beryllium oxide, arsenic oxide, boron oxide, chromium oxide, cobalt oxide, gallium oxide, gold oxide, indium oxide, iridium oxide, lead oxide, manganese oxide, mercury oxide, molybdenum oxide, nickel oxide, osmium oxide, palladium oxide, platinum oxide, silver oxide, thallium oxide, tungsten oxide, vanadium oxide, yttrium oxide, zirconium oxide, titanium oxide, tin oxide, tantalum oxide, ruthenium oxide, rhodium oxide, niobium oxide, neodymium oxide, lanthanum oxide, cadmium oxide, bismuth oxide, acetone (or dimethylketone) , ammonia (nitrogen trihydride) , pyridine, guanidine, n-butyllithium, lithium di-isopropylamide, lithium di-ethylamide, sodium ammoniumide, sodium hydride, lithium bis (trimethylsilyl) amide, potassium sodium carbonate,potassium cyanide, diethylamine, ethylamine, dimethylamine, methylamine, trimethylamine, hydrazine, morphine, nicotine, hydroxylamine, aniline, and urea.

7. Method according to claim 6, characterised in that said oxidising agent is a hydroxide or an oxide selected from the group consisting of magnesium hydroxide and calcium oxide .

8. Method according to claim 1, characterised in that said plasticizer is selected from the group consisting of tri-n-butyl citrate, tributyrin, glycerol, polyglycerol, glycerol triacetate, glycerol tributyrate, chitosan, cellulose nanocrystals, polyethylene glycol, polypropylene glycol, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, butyryl triesyl citrate, salicylic acid, acetyl salicylic acid, ethyl salicylic acid, hexyl salicylic acid, decyl salicylic acid, 2-butyloctyl salicylic acid, ethyl acetylsalicylic acid, hexyl acetylsalicylic acid, decyl acetylsalicylic acid, arylpropionic acid, phthalic acid, triglycidyl isocyanurate, propanediol, 1,4- propanediol, 1 , 2-butanediol , 1 , 3-butanediol , pentanediol, 1 , 5-hexanediol , 1 , 6-hexanediol, 1,3-bis (t- butylperoxyisopropyl ) benzene [1,3-Bis- butylperoxyisopropyl ) benzene] , 1 , 2 , 6-hexanetriol , 1,3,5- hexanetriol, neopentyl glycol, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, sorbitol diethoxylate, sorbitol hexaethoxylate, sorbitol dipropoxylate, aminosorbitol , trihydroxymethylaminomethanebutanediol , neopentyl glycol, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, butyl glucoside, diisononyl adipate, propionate, ortho-cresol, lactone monoethoxylate,mannitol monoacetate, mannitol monoethoxylate, butyl glucoside, glucose monoethoxylate, a-methyl glucoside, sodium salt of tallow carboxymethyl, polyglycerol monoethoxylate, formamide, N-methylformamide, l,3-bis (4,5- dihydro-2-oxazolyl ) benzene, 1, 4-bis (4, 5-dihydro-2- oxazolyl ) benzene, 2 , 2 -bis ( 4 , 5-dihydro-2-oxazolyl ) benzene triallyl isocyanurate, triallyl trimester, triallyl trimesate, trimethylpropane triacrylate, triallyl cyanurate pentaerythrole triacrylate, 1 , 1 , 1-trimethyl olethanetrinitrate, 1,2,4-butane triol trinitrate, 1,3- biscarbazoyl propane, propane 1,2 diol, propane 1,3 diol, 1, 3-diphenylpropane-l , 3-dionate, 2, 2-bis (p-hydroxyphenyl ) propane diglycidyl ether; nitrogen compounds such as phenylurea, N, N ' -diphenylthiourea and 2-phenylindole, 1,4- cyclohexane dimethanol dibenzoate, abietic acid, adipic acid, alkyl sulfonate, azelaic acid, benzoates, dibenzoates, benzoyl acid, chloroparaffin, stearyl citrate, ethyl citrate, butyl citrate, hexyl citrate, polyglycide nitrate, bisdinitropropyl , dimethyl methylenedinitramine, di-2- ethylhexylphthalate, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene, tetrapropylene glycol, glutaric acid, paraffin, isoparaffin, cyclohexane, decalin, naphthalene, dibenzothiophene, carbazole, 2 , 2 , 4-trimethyl-l , 3-pentadiol diisobutyrate, sucrose diacetate hexaisobutyrate, pentaerythrol, phosphoric acid, phthalic acid, isoprene, isobutylene, methyl vinylidene, ricinoleic acid, p-toluene sulphonamide, n- butylbenzene sulphonamide, trimellytate, pyromellytate, dicyclohexylbiphenyl, calcium stearate, diurethane, 2- (2'- hydroxyphenyl ) benzotriazole, such as 2- ( 2 ' -hydroxy-5 ' -methylphenyl) -benzotriazole-2-hydroxybenzophenone, an unsubstituted or substituted benzoic acid ester, such as 4- tert-butylphenyl salicylate, phenyl salicylate, acrylate, nickel compound, oxalamide such as 4 , 4 ' -dioctyloxyoxanilide, 2 , 2 ' -dioctyloxy-5, 5 ' -ditert-butyleusanilide, 2— (2— hydroxyphenyl) -1, 3, 5-triazine, such as 2 , 4 , 6-tris ( 2- hydroxy-4-octyloxyphenyl ) -1, 3, 5-triazine 2- ( 2-hydroxy-4- octyloxy) phenyl ) -4 , 6-bis (2, 4-dimethylphenyl) -1, 3, 5- triazine and sterically hindered amines such as bis (2, 2, 6, 6- tetramethylpiperidin-4-yl sebacate) ) , and bis (2,2, 6, 6- tetramethylpiperidin-4-yl ) succinate .

9. Method according to claim 8, characterised in that said plasticizer is tri-n-butyl citrate.

10. Method according to claim 1, characterised in that said mixture comprises an oxidising agent and a plasticizer.

11. Method according to claim 1 wherein said polyhydroxybutyrate is present in the mixture in a percentage of between 5% and 90% by weight on the total weight of said mixture, preferably between 15% and 70%, more preferably between 15% and 30% by weight on the total weight of said mixture .

12. Method according to claim 1 wherein said second polymer is present in the mixture in a percentage of between 10% and 95% by weight on the total weight of said mixture, preferably between 30% and 85%, more preferably between 70% and 85% by weight on the total weight of said mixture.

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