Biodegradation of poly(vinylalcohol-co-ethylene) with the fungus phanerochaete chrysosporium

Abstract  

Under appropriate conditions for lignine peroxidase production in a culture medium that contains spores of Phanerochaete Chrysosporium fungus, the biodegradation of ethylene vinyl alcohol (EVOH) pellets with 27% mole of ethylene content was observed after 30 days. The oxidative degradation was detected by Fourier Transform Infrared Spectroscopy (FTIR) through the formation of hydroperoxides containing chains which were broken with degradation time. Differential Scanning Calorimetry (DSC) initially showed only one melting peak and after 30 days two peaks appeared on the thermogram, one due to the remaining copolymer that did not change with degradation time and the other due to the polymer degradation sequence.

When EVOH film with a similar amount of ethylene was used, the initial melting temperature (T_m) decreased during degradation and a second crystalline sequence with a lower T_m was produced, indicating that both copolymer sequences were degraded. Observed differences in the biodegradative behavior between EVOH pellets and EVOH film were mainly due to the changes in crystallinity of the copolymer induced by film processing. The initial EVOH film showed a lower crystallinity and the presence of double bonds, which favors the degradative process.