Effects of geometric structure in unsaturated aliphatic polyesters on their biodegradability

Melt or solution polycondensation of cyclic anhydrides (succinic, methylsuc cinic. maleic. and citraconic) or fumaric acid with ethylene glycol was con ducted under various conditions. The resulting unsaturated polyesters were found to have various ratios of different two configurations at the C=C dou ble bond from their H-1 and C-13 NMR spectra. The biodegradability of these polyester samples was evaluated from enzymatic degradation tests with Rizo pous delemar lipase, and biochemical oxygen demand (BOD) values in an activ ated sludge. Introducing methyl group on the polymer chain tends to reduce its biodegradability. In comparison with saturated polyesters. efficient bi odegradation was prevented by unsaturated monomer units. particularly by Z- configuration of C=C double bond.