The Effect of Irradiation Sterilization on Poly(Lactic) Acid Films
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ORIGINAL PAPER
The Effect of Irradiation Sterilization on Poly(Lactic) Acid Films Patnarin Benyathiar1 · Susan E. Selke1 · Bruce R. Harte1 · Dharmendra K. Mishra2 Accepted: 15 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Ionizing radiation is known to cause the deterioration of polymeric materials. In this study, the goal was to determine the effect of gamma and E-beam radiation on poly(lactic) acid (PLA) film at irradiation dosages of 1 to 30 kGy and on postirradiated PLA after 9-months storage. The physical, chemical, mechanical, thermal, and permeability properties were investigated. Ionizing radiation of the commercial PLA film resulted in a decrease in molecular weight, crystallization temperature and melting temperature Tc and T m, which suggested a degradation of PLA by irradiation. Irradiation had no effect on the color of the PLA film. The surface tension of PLA was decreased by gamma irradiation at dose of 1–10 kGy and E-beam irradiation at dose of 1–5 kGy. A decrease in the tensile strength, break elongation and elastic modulus was found for the gamma and E-beam irradiated PLA. Irradiation resulted in a decrease in water vapor and carbon dioxide permeability of PLA while there was no effect on oxygen permeability. Keywords Bio-based material · PLA · Ionizing radiation · Packaging sterilization · Packaging material properties Abbreviations CoPLA Non-irradiated poly (lactic) acid GMPLA Gamma irradiated poly (lactic) acid EBPLA E-beam irradiated poly (lactic) acid
Introduction Presently, the use of synthetic packaging materials has been reduced and/or replaced by biodegradable materials due to the current ecological problems and increasing environmental awareness [1]. Polylactic acid (PLA) is a biodegradable polymer that is also biocompatible. PLA is a linear aliphatic thermoplastic polyester obtained by ring-opening polymerization of lactide dimer a fermentation product available from the conversion of dextrose, which is derived from renewable resources such as corn, sugar beets, rice, sugarcane, To represent the sample codes at different storage times, 3M (3 months), 6M (6 months) and 9M (9 months) were used as an extension to the codes presented above. * Patnarin Benyathiar [email protected] 1
School of Packaging, Michigan State University, 448 Wilson Rd., East Lansing, MI 48824‑1223, USA
Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
2
wheat and sweet potato [2, 3]. The fermentation of carbohydrates can produce lactic acid, which is a basic constituent of PLA. Lactide dimer exists in three different forms: L,Llactide (called L-lactide), D,D-lactide (called D-lactide) and L,D-lactide or D,L-lactide (called meso-lactide) [4]. PLA properties depend on the ratio of the L- to the D-isomer of lactic acid [5]. PLA is a unique polymer since it behaves like polyethylene terephthalate (PET) and also like polypropylene (PP). Moreover, its ability to be stress crystallized, thermally crystallized, impact modified, fil
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