SYNTHESIS AND CONTROLLED PHOTODEGRADABILITY AND BIODEGRADABILITY OF LY[(HYDROXYBUTYRATE-CO-HYDROXYVALERATE)-G-STYRENE]

The graft copolymer, P(HBV-g-St), was synthesized by graft polymerizat ion of styrene (St) onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [PHBV] under nitrogen atmosphere using benzoyl peroxide (BPO). The str ucture of ly[(hydroxybutyrate-co-hydroxyvalerate)-g-styrene] [P(HBV-g- St)] was identified by FT-IR, H-1-NMR and C-13-NMR spectra. The effect s of weight ratio of St to PHBV in feed, initiator concentration, reac tion time and reaction temperature on the grafting ratio and grafting efficiency were investigated. The thermal decomposition temperature of P(HBV-g-St) was 273 degrees C. The tensile strengths of P(HBV-g-St) b efore and after photo- or biodegradation were also measured. The photo degradability of P(HBV-g-St) was better than that of PHBV. The film su rface of P(HBV-g-St) treated with Aspergillus nigger showed extensive grooves and pits as compared with the untreated P(HBV-g-St). It was fo und that the photo- and biodegradation rates of P(HBV-g-St) and tensil e strength of P(HBV-g-St) can be ''controlled'' by changing the weight ratio of St to PHBV in feed.