PHBV and PEA Based on Biodegradable HMAs

PHB is produced by micro-organisms apparently in response to the conditions of physiological stress. The poly-3-hydroxybutyrate (P3HB) form of PHB is probably the most common type of polyhydroxyalkanoate, but many other polymers of this class are produced by a variety of polymers including poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhy-droxyoctanoate (PHO) and their copolymers. [84] 

In order to enhance the property of the HMA, some proper additives are used. Grigat Ernst et al. [91] developed a kind of PEA-based biodegradable HMA. The ester segments of the PEA used consist of oligo-esters with Mn=800- 1300 and 2 COOH end-groups obtained by melt condensation of diols with adipic acid and the amide segments are preferably obtained by reaction of these COOH end-groups with hexamethylene diisocyanate. The ordinary additives such as plasticizers, fire retardants, and/or fillers were mixed into the system. 

Besides, Sasaki Shingo et al. [92] prepared a biodegradable HMA. The HMA comprised aliphatic polyester resin, which was obtained by depolymerizing an aliphatic polyester resin. The test results suggested that the HMA had a well 

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