PHV poly

Many other polymers of this class are produced by a variety of organisms these include poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), poly-hydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO) and their copolymers. 

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. 

Phenoxy Polyhydroxyether of bisphenol-A PHV Poly(hydroxy valerate)... 

However, the major reaction following radiolysis of poly glutamic acid is decarboxylation (Hill, D.J.T. Ho, S.Y. O Donnell, J.H. Pomery, P.J. Radiat. Phvs. Chem.. submitted for publication). 

The copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-PHV) produced by A eutrophus has generated more interest than poly-(R)-3-hydroxybutyrate (PHB) homopolymer. Since these bacterial polyesters are biodegradable thermoplastics, their mechanical and physical properties have received much attention. PHB is a relatively stiff and brittle material because of its high crystallinity. However, the physiochemi-cal and mechanical properties of [P(HB-HV)] vary widely and depend on the molar percentage of 3-hydroxyvalerate (HV) in the copolymer (4,5) as shown inTable 1. Propionic acid is converted by a synthetase to propionyl-CoA, and the biosynthetic P-ketothiolase catalyzes the condensation of propionyl-CoA with acetyl-CoA to 3-ketovaleryl-CoA by the acetoacetyl-CoA reductase. The hydroxyvaleryl moiety is finally covalently linked to the polyester by the PHA synthase (6). 

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 . 

PHB-co-PHV [54] is obtained from Azotobacter chroococcum [58, 63). The biodegradation is slower for the copolymers than poly-3-hydroxybutyrate. 3-hydroxy-n-phenylalkanoic acids and 3-hydroxyaliphatic acids are obtained from Pseudomonas putida [59]. Poly (3-hydroxyoctanoic acid) and poly (6-hydroxyhexanoic acid) and poly (3-hydroxyoctanoic acid) [64], Poly-(R)-3-hydroxybutyrate/polyphosphate (PHB/polyP) complexes are isolated from the plasma membranes of bacteria [65,66]. Polyhydroxyoctanoate is produced by feeding octanoic acid to Pseudomonas oleovorans [67]. 

Poly(hydroxy alkanoate), PHA, [poly(hydroxy butyrate) PHB, poly(hydroxyl valerate) PHV]... 

Shen X-W, Yang Y, Jian J, Wu Q, Chen G-Q (2009) Production and characterization of homopolymer poly(3-hydroxyvalerate) (PHV) accumulated by wild type and recombinant Aeromonas hydrophila strain 4AK4. Bioresour Technol 100 4296-4299 Shenoy SL, Bates WD, Frisch HL, Wnek G (2005a) Role of chain entanglements on fiber formation during electrospinning of polymer solutions good solvent, non-specific polymer-polymer interaction limit. Polymer 46 3372-3384... 

Uchi5rama, A., and Yatabe, T. (2003). Analysis of extraordinary birefringence dispersion of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide)/atactic pol5rstyrene blend films. Ion. I. Add/. Phvs.. 42, 3503-3507. 

Figure 21.9 The biodegradable polyester family poly(hydroxyalkanoates) (PHA), poly(hydroxybulyrate) (PHB), poly(hydro3qdiexanoate) (PHH), poly(hydrox3rvalerate] (PHV), polyflactic acid) (PLA), poly(caprolactone) fPCL), poly(butylene succinate) (PBS), poly(butylene succinate adipate) (PBSA), aliphatic-aromatic copolyesters (AAC), poly(ethylene terephthalate) (PET), poly(butylene adipate/terephthalate) (PBAT), poly(methylene adipate/terephthalate) (PTMAT). Adapted from [103].

Li,Y.,Wang,Y.,Liu,L,Han,L.,Xiang,F.,andZhou,Z.(2009).Crystallization improvement of poly(L-lactide) induced by functionalized multiwalled carbon nanotubes. I. Polvm.. 9c/. Part B Polvm. Phvs.. 47, 326-339. 

Kim, Y., Jung, R., Kim, H. S., and Jin, H. J. (2009). Transparent nanocomposites prepared by incorporating microbial nanofibrils into poly(L-lactic acid). Curr. AddI. Phvs.. 9, S69-S71. 

Ogata, N., Jimenez, G., Kawai, H., and Ogihara, T. [1997J. Structure and thermal/mechanical properties of poly(L-lactideJ-clay blend. 1. Polvm. Set Parts Polvm. Phvs.. 35, 389-396. 

Besides the common polyhydroxybutyrate (PHB), other polymers of this class are produced by a variety of organisms such as poly-4-hydroxybutyrate, PHV, and polyhy-droxyhexanoate. PHV is a naturally occurring bacterial polyester, which was first isolated by Wallen and coworkers [172,173]. Also, PHV/PHB copolymers have been studied to make a wide range of thermally processable polyesters, which exhibit the necessary long-term degradation profile required for a degradable fracture fixation device [174]. 

Nagai, K., Sugawara, A., Kazama, S. and Freeman, B.D. 2004. Effects of physical aging on solubility, diffusivity, and permeability of propane and n-butane in poly(4-methyl-2-pentyne). J. Polvm. Sci. B Pol. Phvs. 42(12) 2407-2418. 

Kravets, L., Dmitriev, S., Lizunov, N., Satulu, V, Mitu, B. and Dinescu, G. 2010. Properties of poly(ethylene terephthalate) track membranes with a polymer layer obtained by plasma polymerization of pyrrole vapors. Nucl. Instrum. Methods Phv.[Pg.208]

Poncin-Epaillard, R, Medard, N. and Souti, J.C. 2000. Reactivity of surface groups attached on a plasma treated poly(propylene) film. Application to a new concept of a chelating membrane. Macromol. Chem. Phvs. 201 212-219. 

Polylactic acid (PLA), polyglycolate (PGA), poly(3-hydroxybutyrate), polyc-aprolactone (PCL), polyhydroxyvalerate (PHV) and their copolymers poly(butylene succinate) (PBSu), poly(ethylene succinate) (PESu), poly(propylene adipate) (PPAd), etc., are the most commonly used aliphatic polyesters for such applications as packaging materials, mulch Aims, tissue engineering, implants, drug delivery etc. 

For example, natural biopolymers have been developed for use in the manufacturing of plastic containers. Poly-(hydroxyalkanoates) such as poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyvalerate) (PHV) are naturally occurring polyesters produced by certain bacteria. 

PHB has many physical properties in common with poly(propylene), and a PHB-PHV copolymer (BIOPOL) has recently been used to manufacture plastic shampoo bottles. PHB-PHV is of special interest because it is biodegradable. Since it is a naturally occurring polymer, it is easily degraded by enzymes produced by soil microorganisms and therefore does not persist in the environment after disposal. Other biodegradable polymers, such as polyesters derived from e-caprolactone and lactic acid, are also known and have been commercialized. Although it remains to be seen how widespread the use of biodegradable plastics will become, research and development of these materials is sure to continue as we try to deal with contemporary environmental issues. ... 

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