Physico-chemical characteristics of biodegradable poly (lactic acid) and poly (lactic acid)/ chitosan composites under the influence of gamma irradiation

Abstract

PLA and its nanocomposite containing 3% chitosan nanoparticles (PLA-3CsNP) were studied to see how γ -irradiation affected their characteristics. Different doses of γ -irradiation were applied to the investigated materials under inquiry (5–40 kGy) using 60Co at ambient condition. The irradiation materials were characterized by FT-IR, GPC, mechanical tensile test, DSC, XRD, and TGA in solid and chloroform solutions. The molecular weight of the studied materials was lowered when the irradiation dose was increased, indicating that γ-irradiation had the dominating effect through oxidative degradation, and chain scission. The addition of chitosan to PLA reduces the impact of γ-irradiation, while the samples irradiated in solution showed more degradation after irradiation than irradiated solid films. Irradiation caused a decrease in tensile strength and elongation at break values. Both the melting temperature (Tm) and the glass transition temperature (Tg) decreased as the irradiation dose was increased. The cold crystallization peak temperatures were reduced when pure PLA was irradiated in solution. The thermal stability of PLA was diminished as the irradiation dose was raised, and this effect was more pronounced in samples irradiated in chloroform solution.