The Effects of Gamma Irradiation on Molecular Weight, Morphology and Physical Properties of PHBV/Cloisite 30B Bionanocomposites

摘要

In this paper,the effects of gamma irradiation on Cast poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)and PHBV/Cloisite 30B(C30B)(3 wt%)bionanocomposite prepared by melt compounding,were evaluated at various doses,i.e.,5,15,20,50 and 100 kGy at room temperature in air.Changes in molecular weight,morphology and physical properties were investigated.The study showed that the main degradation mechanism occurring in gamma irradiation in both Cast PHBV and C-PHBV/3C30B bionanocomposite is chain scission,responsible for the decrease of molecular weight.Differential scanning calorimetry(DSC)data indicated a regular decrease in crystallization temperature,melting temperature and crystallinity index for all irradiated samples with increasing the dose.Further,DSC thermograms of both Cast PHBV and PHBV bionanocomposite exhibited double melting peaks due probably to changes in the PHBV crystal structure.Tensile and DMA data showed a reduction in Young’s modulus,strength,elongation at break and storage modulus with the radiation dose;the decrease was however more pronounced for Cast PHBV.The morphological damages were much less pronounced for the PHBV bionanocomposite sample compared to Cast PHBV,for which some irregularities and defects were observed at 100 kGy.This study highlighted the ability of C30B to counterbalance the detrimental effect of radiolytic degradation on the functional properties of PHBV up to 100 kGy,thus acting as a potential anti-rad.