Effects of geometrical difference of unsaturated aliphatic polyesters on their biodegradability III. Cross effects of molecular weight and geometric structure of poly(ethylene maleate/fumarate) and its model compounds

Abstract

Unsaturated polyesters, P1a and P2a, having different molecular weight were synthesized by solution polycondensation of maleic anhydride (MAn) with ethylene glycol (EG). Furthermore, unsaturated polyesters, poly(ethylene maleate/fumarate) (P1b-e and P2b-e), which have various ratios of different Z-/E-configuration at the C=C double bond were readily delivered from P1a and P2a, respectively, in 1,2-dichloroethane by using morpholine as a catalyst for isomerization. In order to discuss separately the effects of molecular weight of the samples on their biodegradability from the effects due to configuration of C=C double bond, several Z- or E-rich oligomeric model compounds having methyl esters as the terminal groups were prepared. The biodegradability of these polyester samples and oligomeric model compounds was evaluated from biochemical oxygen demand (BOD) values in the presence of an activated sludge. As the number-average molecular weight of both oligomeric model compounds and unsaturated polyesters was higher, their biodegradability was lowered by introducing C=C double bond, especially, by that of Z-configuration.