Syntheses and photobiodegradable properties of graft copolymers of vinyl ketones and starch

Graft copolymerizations of methyl vinyl ketone (MVK) or phenyl vinyl ketone (PVK) on to starch (S) were carried out with eerie ammonium nitrate (CAN) as initiator. The structures of the synthesized graft copolymers, S-g-poly(MVK) and S-g-poly(PVK), were identified by FT-IR spectroscopy. The thermal stability was also determined by TGA. The photodegradation of the graft copolymers was investigated by Fade-o-Meter and the biodegradation was estimated for the samples incubated with Aspergillus niger. The weight average molecular weights of the grafted side chains isolated from the original graft copolymers after UV irradiation were in the ranges of 3700 similar to 6400 compared to those of the same chains with 68000 similar to 168000 of samples before irradiation. The graft copolymers showed higher photodegradable properties because of the carbonyl-containing polymers in the graft copolymers. In photobiodegradation tests, the graft copolymers exhibited extensive grooves and pits due to photobiodegradable properties of carbonyl and starch moieties. (C) 1998 Elsevier Science Limited. All rights reserved.