HYDROXY VALERATE COPOLYMER

Rosin and its derivatives are frequently used as polymer additives in different capacities. Their role as plasticizers is illustratedby recent work related to the paper coating for foodpackaging with a 3-hydroxybutirate/3-hydroxy valerate copolymer (PHBW) [112, 113]. The addition of tall oil rosin to the copolymer was found to improve its water vapour barrier properties as well as to reduce the pinhole density of the corresponding laminated papers. 

Millar, N. D. and Williams, D. F. (1987) On the biodegradation of poly (j5-hydroxybutyrate) (PHB) homopolymer and poly (j -hydroxybutyrate/hydroxy-valerate) copolymers. Biomaterials, 8,129-37. 

Some specific recent applications of the GC-MS technique to various types of polymers include the following PE [49,50], poly(l-octene) [51], poly(l-decene) [51], poly(l-dodecene) [51], 1-octene-l-decene-l-dodecene terpolymer [51], chlorinated polyethylene [52], polyolefins [53, 54], acrylic acid methacrylic acid copolymers [55], polyacrylates [56], styrene-butadiene and other rubbers [57-59], nitrile rubber [60], natural rubbers [61, 62], chlorinated natural rubber [63, 64], polychloroprene [65], PVC [66-68], silicones [69, 70], polycarbonates [71], styrene-isoprene copolymers [72], substituted PS [73], polypropylene carbonate [74], ethylene-vinyl acetate copolymers [75], Nylon [76], polyisopropenyl cyclohexane a-methyl styrene copolymers [77], m-cresol-novolac epoxy resins [78], polymeric flame retardants [79], poly(4-N-alkyl styrenes) [80], polyvinyl pyrrolidone [81], vinyl pyrrolidone-methyl acryloxysilicone copolymers [82], polybutylcyanoacrylate [83], polysulfide copolymers [84], poly(diethyl-2-methacryloxy)ethyl phosphate [85], ethane-carbon monoxide copolymers [86], polyetherimide [87], bisphenol A [88], ethyl styrene [89], styrene-isoprene block copolymer [89], polyvinyl alcohol-co-vinyl acetate [90], epoxide thiol [91], maleic acid-propylene copolymer [92], P-hydroxy butyrate-P-hydroxy valerate copolymer [93], polycaprolactams [39,94], PS [95,96], polypyrrole [95,96], polyhydroxy alkanoates [97], poly(p-chloromethyl) styrene [81], polybenzooxazines and siloxy substituted polyoxadisila-pentanylenes [98,99] poly benzyl methacrylates [100], polyolefin blends after ageing in soil [101] and polystyrene peroxide [43]. 

Wang used reactive-extrusion polymerization with 2,5-di-methyl-2,5-di-t-bu-tylperoxy hexane to prepared a graft copolymer, (11), by free radically grafting polyethylene-glycol malonic acid onto the biodegradable substrate of poly((3-hydroxybutyrate-co- p-hydroxy valerate). 

This is a copolymer consisting of hydroxybutyrate and hydroxy valerate units incorporated randomly along the chain. The hydroxyvalerate content may be varied by adding controlled amounts of a simple organic acid. 

Synthetic or man-made, e.g., PVAl, CA, polylactams e.g., polycaprolactam), polyglycols (e.g., polyethylene glycol), poly(aspartic acid), poly(butylene succinate-co-adipate), as well as poly(3-hydroxy butyrate) or PHB, poly(P-hydroxybutyric acid) or PHBA, poly(hydroxy-valerate) or PHV, poly(lactic acid) or PLA, polyCglycolic acid), polyglycolides, polybu-tyric acid, their copolymers and mixtures. 

Higher molecular weight PHB and its copolymers with poly(3-hydroxy-valerate) (PHV) can be synthesized from racemic P-butyrolactone and P Valerolactone, using an oligomeric alumoxane catalyst. These polyesters, with only partial stereoregularity, are less susceptible to enzymatic degradation than the bacterial ones. Polyhydroxy-butyrate-valerate (PHBV) is produced by Monsanto as Biopol . 

EVAl 3-hydroxy butyrate-valerate copolymer Webb et al., 1992... 

The functional architecture of this class of PHA copolymers is substantially different from that of more familiar types of PHAs, such as poly[(/ )-3-hydroxybutyrate] (PHB) homopolymer or poly[(/ )-3-hydroxybutyrate-c<9-(/ )-3-hydroxy valerate] (PHBV) copolymer. The size of the side groups in the conventional PHAs is limited only to short-side-chain types with no more than two carbon atoms. Although PHAs with only one or two carbon side groups may be viewed essentially as linear polymers, PHA copolymers with mcl side groups belong to a broad class of moderately branched polymers. The inclusion of a small amount of mcl-3HA units into the PHA polymer backbone leads to some profound changes in important physical properties of this class of copolymers. 

Fig. 5.17 Plot of melting temperature against the melt composition for random copolymers of 3-hydroxy butyrate and 3-hydroxy valerate. (From Scandala, et al. (131))...

Solid-state carbon-13 NMR studies of these copolymers also demonstrate isodimorphism over the complete composition range.(135,136) These studies are consistent with the plot in Fig. 5.17 and the x-ray diffraction results. Moreover, the NMR studies have also shown that the 3HB/3HV ratio in the crystalline phase of poly-(3-hydroxy butyrate-co-3-hydroxy valerate) is less than that for the nominal composition of the copolymer. The minor component thus enters the lattice at a smaller concentration than the composition of the pure melt. The ratio of 3HV in the crystal to that in the melt increases with increasing 3HV content. In principle, a complete conventional type phase diagram based on composition could be obtained by this method. We should recall, however, that when treating copolymers the important quantity is the sequence distribution within the crystal relative to that of the melt. 

Most of the papers on PHA fibres deal with poly(hydroxybutyrate). Although sometimes a copolymer of PHB with a low amount of poly(hydroxy valerate) is also referred to as PHB in the literature quoted in this review such inconsistency is not expected. The reason for not using PHBV may consist in the fact that the copolymer has a much lower crystallinity and consequently, also, modulus is lower compared to PHB. Thus, the processing to fibres may be more difficult because of low crystalline content and also the properties of the fibres may be expected to be less impressive. Moreover, PHBV itself is much tougher compared to PHB, but also more expensive, so that the need of an improvement of toughness via drawing is not crucial while the price may be prohibitive if the expected modest improvement in the properties of fibres is considered. 

High molecular weight poly(3-hydroxy-butyrate) and its copolymers poly(3-hydroxy-valerate) can also be produced synthetically from butyrolactone and p-valerolactone, using an oligomeric alumoxane catalyst. 

Poly(b-hydroxybutyric acid), PHBA 3-hydroxy butyrate-valerate copolymer Polylactic acid, PLA, polyglycolides, polybutyric acid or copolymers of butyric and valeric acid... 

In particular, this chapter will concentrate on the physical properties of the first polyhydroxyalkanoates to be commercially exploited, the Biopol resins, launched by ZENECA Bio Products, Billingham, UK. These materials are copolymers of 3-hydroxybutyric acid (3HB) and 3-hydroxy valeric acid (3H V) ... 

The presence of a second monomer in PHAs copolymers seems to have a certain stabilizing effect in thermal degradation, as revealed by thermogravimetry for PHB, and its copolymers with hydroxy valerate and hydroxyhexanoate [12]. Moreover, in the case of... 

An example of isodimorphism, and the related crystallization kinetics, is typified by the random copolymers of 3-hydroxy butyrate-3-hydroxy valerate.(82) The melting temperature-composition relation of this copolymer was given in Fig. 5.17 (Volume 1). For this copolymer, depending on the composition, either of the comonomers can co-crystallize in the other s lattice. When the concentration of the 3-hydroxy butyrate is less than 40 mol percent, crystallization occurs in the poly(3-hydroxy butyrate) lattice. When its concentration is greater than 40 mol percent, crystallization takes place in the poly(3-hydroxy valerate) lattice. The copolymer that contains 41 mol percent of 3-hydroxy valerate reflects the coexistence of both crystal phases and corresponds to a pseudo-eutectic composition. 

It is well known that certain kinds of bacteria, e.g., Azotobacter, Bacillus, Alcaligenes, and Zoogloea, accumulate high amounts of poly[(/ )-3-hydroxybutyrate] when they are cultured under limited nitrogen conditions. (/ )-p-Hydroxybutyric acid ester of high optical purity (100% e.e.) was obtained by alcoholysis of this biopolymer [9]. When propionic acid and glucose were used as the carbon sources, Alcaligenes eutrophus produced a copolymer of (/ )-p-hydroxybutyric acid and (/ )-P-hydroxyvaleric acid. (/ )-p-Hydroxy-valeric acid ester (100% e.e.) was obtained from this copolymer by a procedure similar to that described above [16] (Scheme 6). 

Composites of granular starch with poly(hydroxy alkanoates) (PHAs) have been extensively studied. PHAs are produced as energy storage polymers by a wide range of microorganisms. Poly(hydroxy butyrate-co-valerate) (PHBV) copolymers have been commercialized. These copolymers are completely biodegradable, but currently are several times more costly than commodity polymers such as PE and PS. Because of its low cost, starch is an attractive filler for these materials. 

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