Influence of monomeric composition on properties of MMC-produced polyhydroxyalkanoates

This study aims at investigating the effect of the 3-hydroxyalerate (3HV) units concentration on the properties of poly-3hydroxybutyrate-co-3hydroxyvalerate copolymers (PHBV). Different samples, char- acterized by a high 3HV content, were produced in mixed microbial cultures by vaying the operating condi- tion and extracted in chloroform. The comparison of the results of the thermal and morphological character- ization with those obtained by variable temperature FTIR spectroscopy evidenced a complex behavior due to the heterogeneous chemical structures of the samples, possibly composed of copolymers with different composition and homopolymers. Stress-strain tests showed that the mechanical properties depend directly on sample crystallinity, indirectly related to copolymer compositions.