Method for preparing biodegradable polyhydroxyalkanoate - copolymers having improved crystallization properties

摘要

A method for enhancing the rate of a first biodegradable polyhydroxyalkanoate comprising a copolymer, or a blend thereof, of at least two randomly repeating monomer units (RRMU), wherein the first RRMU has the structure (I) wherein R1 is H, or C1 or C2 alkyl, and n is 1 or 2; and the second RRMU is different from the first RRMU and comprises at least one monomer selected from the group consisting of the structures (II) wherein R2 is a C3-C19 alkyl or C3-C19 alkenyl, and (III) wherein m is from 2 to about 16, and wherein the copolymer has a melting point Tm1, by solution blending or melt blending the first biodegradable polyhydroxyalkanoate with (b) a second crystallizable biodegradable polyhydroxyalkanoate homopolymer or copolymer, which comprises at least one randomly repeating monomer unit having the structure (IV) wherein R3 is H, or C1 or C2 alkyl, and p is 1 or 2. The second biodegradable polyhydroxyalkanoate has a melting point Tm2, wherein Tm2 is at least about 20 °C greater than Tm1. Methods for forming shaped articles from the blending of components (a) and (b) are also disclosed.