Preparation and Properties of a Novel Class of Polyhydroxyalkanoate Copolymers

Abstract

Polyhydroxyalkanoates (PHAs) are biodegradable aliphatic polyesters, known to be produced by many common microorganisms. Nodax is a recently introduced family of PHA copolymers comprising 3-hydroxybutyrate units and a relatively small amount of other medium chain length 3-hydroxyalkanoate (mcl-3HA) comonomers with side groups of at least three carbon units or more. There are several different grades of copolymers available, depending on the average molecular weight, average mcl-3HA content within the copolymer, and side group chain length of the chosen mcl-3HA unit. PHA copolymers with different mcl-3HA types and contents can be made either by bacterial fermentation or by chemical synthesis. The incorporation of mcl-3HA units into PHAs effectively lowers the crystallinity and T(m) in a manner similar to the effect of alpha-olefins in linear low-density polyethylene. The T(m) can be lowered well below the thermal decomposition temperature of PHAs to make this material much easier to process. The reduced crystallinity provides the ductility and toughness required for many practical applications. The mcl-3HA content regulates the T(m) and crystallinity of copolymer almost independently of the branch size, as long as more than three carbons are present in the side group. On the other hand, the side group chain length of the mcl-3HA has a profound effect on the flexibility of copolymer.

Production of renewable polymers from crop plants

“…The simplest PHA, poly-3-hydroxybutyrate (PHB), is a relatively hard and brittle material with a melting point that is slightly below the thermal decomposition temperature (Lenz and Marchessault, 2005). While the use of C5 monomers to produce poly(3-hydroxybutyrateco-3-hydroxyvalerate) [P(HB-co-HV)] improves the properties of the material to some extent, inclusion of a small proproportion of longer monomers (C6 and longer) has resulted in materials that are much easier to process, and are similar to polypropylene (Noda et al, 2005). PHAs consisting of higher-molecular-weight monomers (C6-C16, referred to as medium-chain-length PHA; mclPHA) are typically rubberlike materials with an amorphous soft/sticky consistency.…”

“…This type of polymer has been developed by Proctor & Gamble and Kaneka under the trade name Nodax Ò (Noda et al, 2005). Enzymes that accept both types of monomers include the native PHA synthases from A. caviae and Pseudomonas sp.…”

Properties of melt-processed poly(hydroxybutyrate-co-hydroxyvalerate)/starch 1:1 blend nanocomposites

“…Improved properties have been achieved for PHA copolymers of 3-hydroxybutyrate and other medium-chain length 3-hydroxyalcanoate comonomers. An increase in toughness, flexibility and processability, and a reduction in crystallinity and brittleness were observed for copolymers with a relatively small amount of those comonomers [6] . To improve the properties of PHAs, composites [7][8][9][10][11][12][13] and polymer blends [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] were also studied.…”

Mining the Information Content Buried in Infrared and Near-Infrared Band Shapes by Temporal, Spatial, and other Perturbations

“…5 This blend system is of special current interest, as both polymers are biodegradable plastics made from renewable resources. 6,7 The structures of PLA and P(3HB-co-3HHx) are given in Scheme 1.…”