Blends of Polyhydroxyalkanoates

Renard, E., Walls, M., Gu6rin, P., Langlois, V. Hydrolytic degradation of blends of polyhydroxyalkanoates and functionalized polyhydroxyalkanoates. Polym. Degrad. stab. 85(2), 779-787 (2004)... 

Some synthetic polymers like, polyurethanes, specifically polyether-polyurethanes, are likely to be degraded by microbes but not completely. However, several polymers such as, polyamides, polyfluorocarbons, polyethylene, polypropylene, and polycarbonate are highly resistant to microbial degradation. Natural polymers are generally more biodegradable than synthetic polymers specifically, polymers with ester groups like aliphatic polyesters [1]. Therefore, several natural polymers such as cellulose, starch, blends of those with synthetic polymers, polylactate, polyester-amide, and polyhydroxyalkanoates (PHAs) have been the focus of attention in the recent years [3]. 

CeccomUi G, PizzoU M, Scandola M (1993) Effect of a low-molecular-weight plasticizer on the thermal and viscoelastic properties of miscible blends of bacterial poly(3-hydroxybutyrate) with cellulose acetate butyrate. Macromolecules 26 6722-6726 Chanprateep S, Kikuya K, Shimizu H, Shioya S (2(X)2) Model predictive controller for biodegradable polyhydroxyalkanoate production in fed-batch culture. J Bacterid 95 157-169 Chen GQ, Wu Q (2005) The application of polyhydroxyalkanoates as tissue engineering materials. Biomaterials 26 6565-6578... 

Renard E, Temat C, Langlois V, Guerin P (2(X)3b) Synthesis of graft bacterial polyesters for nanoparticles preparation. Macromol Biosci 3 248-252 Renard E, Walls M, Guerin P, Langlois V (2004) Hydrolytic degradation of blends of poly hydroxyalkanoates and functionalized polyhydroxyalkanoates. Polym Degrad Stab 85 779-787... 

The first chapter on polyhydrojg alkanoates and their blends, composites and nanocomposites covers the state of the art, new challenges, and opportunities for polyhydroxyalkanoates based studies and research. The second chapter provides an overview of polyhydroxyalkanoates their stmc-ture, properties and sources. The third chapter concentrates mainly on the recovery of polyhydroxyalkanoates. The chapter s authors discuss the... 

T. Gerard and T. Budtova, Preparation and characterization of polyhydroxyalkanoates (PHA) andpolylactide (PLA) blends, presented in part at the 27th World Congress of the Polymer Processing Society, Polymer Processing Society, Morocco, 2011. 

The blending of NR with two types of biodegradable plastics, namely polylactic acid (PLA) and polyhydroxyalkanoates (PHAs) are discussed in this section. 

Amass W, Amass A, Tighe BA (1998) Review of biodegradable polymers uses, current developments in the synthesis and characterization of biodegradable polyesters, blends of biodegradable polymers and recent advances in biodegradation studies. Polym Int 47 89-144 Anderson AJ, Dawes EA (1990) Occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates. Microbiol Rev 54 450-472 Anderson AJ, Haywood GW, Dawes EA (1990) Biosynthesis and composition of bacterial poly(hydroxyalkanoates). Int J Biol Macromol 12 102-105 Bowien B, Kusian B (2002) Genetics and control of CO(2) assimilation in the chemoautotroph Ralstonia eutropha. Arch Microbiol 178 85-93... 

The compatibility of the individual components of polymeric blends can lead to significant effects on the degradation of the polyhydroxyalkanoate component. This has been illustrated in a study on blends of PHB homopolymer with polycaprolactone, poly( 1,4-butylene adipate) and polyvinyl acetate [57]. Blends over wide composition ranges were incubated as thin films in aqueous solutions of an extracellular PHB depolymerase at 37 °C. The relative degradation rates were related to the miscibility and microstructure of the polymeric phases. For blends where PHB formed the continuous phase, degradation was relatively fast. 

Two types of polyhydroxyalkanoate (PHA) biosynthesis gene loci (phb and pha) of Pseudomonas sp. strain 61-3, which produces a blend of poly-3-hydroxybutyrate [PHB] homopolymer and a random copolymer poly(3-hydroxybutyrate-co-3-hydroxyalkanoate) [P(3HB-co-3HA] consisting of 3HA units of 4 to 12 carbon atoms, were cloned and analyzed at the molecular level [274]. In the phb locus, three open reading frames encoding polyhydroxybutyrate (PHB) synthase (PhbCPs), 6-ketothiolase (PhbAPs), and NADPH-dependent acetoacetyl coenzyme A reductase (PhbBPs) were... 

Other blends such as polyhydroxyalkanoates (PHA) with cellulose acetate (208), PHA with polycaprolactone (209), poly(lactic acid) with poly(ethylene glycol) (210), chitosan and cellulose (211), poly(lactic acid) with inorganic fillers (212), and PHA and aUphatic polyesters with inorganics (213) are receiving attention. The different blending compositions seem to be limited only by the number of polymers available and the compatibiUty of the components. The latter blends, with all natural or biodegradable components, appear to afford the best approach for future research as property balance and biodegradabihty is attempted. Starch and additives have been evaluated ia detail from the perspective of stmcture and compatibiUty with starch (214). 

---