Polyhydroxybutyrate-hydroxyvalerate

Results obtained, by both methods, on Kraft paper and polyhydroxybutyrate-hydroxyvalerate (PHB-HV) did not differ [50]. ... 

Specifically, 70-30 parts poly(hydroxy-butyrate-co-hydroxyvalerate) (4 mol% valerate) or polyhydroxybutyrate was mixed with 30-70 parts PCL in an internal mixer at 100° or 160°C in the presence of 0-0.5 parts DCP or DBP radical initiator. Blends were characterized by SEM, mechanical properties, selective solvent extraction, and FTIR. 

Yagmurlu, M. R Korkusuz, R Gursel, I. Korkusuz, P Ors. U. and Hasirci, V. Sulbactam-cefoperazone polyhydroxybutyrate-co-hydroxyvalerate (PHBV) local antibiotic delivery system In vivo effectiveness and biocompatibility in the treatment of implantrelated experimental osteomyelitis. J. Biomed. Mater. Res. 1999, 46 494-503. 

The nomenclature of PHAs and their classification are still in the process of evolving, because new structures are continuing to be discovered. The main biopolymer in the PHA family is a homopolymer polyhydroxybutyrate (PHB). The most conunon copolymer is poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), whose chemical structure is presented in Figure 9.4. However, there are others, such as poly(hydroxybulyrate-co-hydroxyhexanoate) (PHBHx), poly(hydroxybutyrate-co-hydroxyoctanoate) (PHBO) and poly(ltydroxybulyrate-co-hydroxyoctadecanoate) (PHBOd), for example. 

Barak, P., Coquet, Y., Halbach, T.R.. and Molina, J.A.E., 1991, Biodegradability of polyhydroxybutyrate (co-hydroxyvalerate) and starch-incorporated polyethylene plastic films in soils. J. Environ. Qual. 20 173-179. 

Barkoula, N.M., Garkhail, S.K., and Peijs, T. (2010) Biodegradable composites based on flax/polyhydroxybutyrate and its copolymer with hydroxyvalerate. Ind. Crops Prod., 31 (1), 34—42. 

Fig. 2.7 (a) Spherulites in a thin film of polypropylene (Elaine Ann Perkins, University of Reading, UK, unpublished work, 1985), (b) spherulites in polyhydroxybutyrate-co-valerate (Reprinted with permission from Macromolecules, 2010, 43 4441-4444 Wang Z, Li Y, Yang J, Gou Q, Wu Y, Wu X, Liu Pand Gu Q (2010) Twisting of Lamellar Crystals in Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) Ring-Banded Spherulites Copyright (2010) American Chemical Society, (c) Schematic of sphaulite twisted orientations. Redrawn from Hsieh et al. (2014)... 

In the 1970s, PHBV (polyhydroxybutyrate-co-3-hydroxyvalerate) was successfully produced... 

A more recent biodegradable polymer is polyhydroxybutyrate-valerate copolymer (PHBV). These copolymers differ from many of the typical plastic materials in that they are produced through biochemical means. It is produced commercially by ICI using the bacteria Alcaligenes eutrophus, which is fed a carbohydrate. The bacteria produce polyesters, which are harvested at the end of the process. When the bacteria are fed glucose, the pure polyhydroxybutyrate polymer is formed, while a mixed feed of glucose and propionic acid will produce the copolymers. Different grades are commercially available that vary in the amount of hydroxyvalerate units and the presence of plasticizers. The pure hy-... 

Several biopolymers have been used as matrices for bionanocomposites, including starch poly(lactic acid), PLA poly(s-caprolactones), PCLs poly-hydroxyaUcanoates, PHAs, that include polyhydroxybutyrate, PHB and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, and poly(butylene succinate), PBS [10, 36-58, 86]. These matrices can be chemically synthesized or biosynthesized by some organisms [8, 87]. Biopolymers can be classified into four different groups depending on their synthesis (Figure 11.6) [87-89] ... 

PH A polymers comprise mainly homopolymers such as polyhydroxybu-tyrate (PHB) and polyhydroxyhexanoate (PHH), and different copolyesters, polyhydroxybutyrate-co-hydroxyalkanoates such as jx)ly(hydroxybutyrate-co-hydroxyvalerates) (PHBV) and poly(hydroxybutyrate-cohydroxyoctanoate) (PHBO)... 

The last category includes polymers produced by native microorganisms or genetically transformed bacteria. The best-known example of this category is constituted by polyhydroxyalkanoates (PHAs), mainly polyhydroxybutyrate (PHB) and copolymers of hydroxybutyrate and hydroxyvalerate (PHBV). 

Some polyesters are synthesised by certain bacteria such as metabolites which in this way ensure energy stock. Certain bacteria can accumulate up to 80% of their dry weight before auto-hydrolysis (Braunegg, 2002). In this category are found polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), poly(hydroxy-butyrate-hydroxyvalerate) (PHB/HV) and poly-e-caprolactones (PCL). These... 

PCL (polycaprolactone), PEA (polyesteramide), PHBV (polyhydroxybutyrate co-hydroxyvalerates), PHBO (polyhydroxybutyrate co-hydroxyoctonoate), PBSA (poly(butylene succinate/adipate)), PBAT (poly(butylene adipateco-terephthalate)),... 

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