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

Abstract

In this paper, the effects of gamma irradiation on Cast poly(3hydroxybutyrate-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.

Effects of hygrothermal aging on chemical, physical, and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/Cloisite 30B bionanocomposite

“…Furthermore, the results of solubility test corroborate with those obtained by SEC showing no X‐linking formation in the aged samples. Similar result was observed in previous studies [ 33–34 ] dealing with accelerated photooxidation and gamma irradiation of PHBV/3C30B bionanocomposite. According to Deroiné et al [ 35 ] , chain breakage and ester bond hydrolysis are the main reactions occurring during the degradation of PHAs.…”

“…In addition, the samples are too brittle and cannot be tested. According to the literature [33][34] , the decrease in Young's modulus and strength of PHBV during aging is attributed to the decrease of molar mass. Furthermore, the mechanical properties of the bionanocomposite are less altered compared with Cast PHBV.…”

Development of extrusion blown films of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) blends for flexible packaging

“…For comparative purposes, we included literature data for PHBV from the same supplier. 54 Our observed results exhibited a degradation of PHBV likely attributed to the batch mixing process. Thermal degradation during processing is a well-known concern for PHBV, involving random scission through β-hydrogen elimination, even at temperatures close to its melting point.…”

“… Note : Neat polymer data were measured on initial pellets and published in ref., 44 n.p. not present, PHBV molar mass data obtained from ref 54 …”

Effect of Radiation Crosslinking and Surface Modification of Cellulose Fibers on Properties and Characterization of Biopolymer Composites

“…At higher levels of gamma radiation, due to the considerable chain splitting, there is also a significant decrease in mechanical properties of the PHBV biocomposite. The negative effect of higher levels of gamma radiation on the decrease of mechanical properties of PHBV composite systems was recorded in the work of K. Iggui [ 40 ].…”