On the Mechanism of Electron Beam Radiation-Induced Modification of Poly(lactic acid) for Applications in Biodegradable Food Packaging

Eleanor C Grosvenor,Charlotte M Wentz,Catherine A Lewis,Justin C Hughes,Lilly Ding,Olivia L Mihok,Lorelis González López,Robert L Blanchard,Andrea C Fox,Sydney M Whitaker,Chris Acha,Mohamad Al-Sheikhly,Cade W Stanfield,Ananya Uniyal,Kristen Lee,Jonathan R Brodsky,Kalina Gibson,Lawrence R Sita,Ann Hoy

doi:10.3390/app12041819

Eleanor C Grosvenor, Charlotte M Wentz + Show 17 more

Open Access

https://doi.org/10.3390/app12041819

Copy DOI

Journal: Applied Sciences	Publication Date: Feb 10, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: University of Maryland, College Park

Abstract

Poly(lactic acid) (PLA) is a biodegradable polymer used for food packaging. The effects of electron beam radiation on the chemical and physical properties of amorphous PLA were studied. In this study, amorphous, racemic PLA was irradiated at doses of 5, 10, 15, and 20 kGy in the absence of oxygen. Utilizing electron paramagnetic resonance spectrometry, it was found that alkoxyl radicals are initially formed as a result of C-O-C bond scissions on the backbone of the PLA. The dominant radiation mechanism was determined to be H-abstraction by alkoxyl radicals to form C-centered radicals. The C-centered radicals undergo a subsequent peroxidation reaction with oxygen. The gel permeation chromatography (GPC) results indicate reduction in polymer molecular mass. The differential scanning calorimetry and X-ray diffraction results showed a subtle increase in crystallinity of the irradiated PLA. Water vapor transmission rates were unaffected by irradiation. In conclusion, these results support that irradiated PLA is a suitable material for applications in irradiation of food packaging, including food sterilization and biodegradation.

Highlights

Introduction1.3 billion tons of food are wasted globally [1,2]
Every year, 1.3 billion tons of food are wasted globally [1,2]
Despite the fact that electron beam radiation provides a high dose rate and the absence of oxygen, the electron paramagnetic resonance (EPR) and gel permeation chromatography (GPC) results demonstrate that the predominant effect of radiation is the scission

Summary

Introduction

1.3 billion tons of food are wasted globally [1,2]. This figure corresponds to almost one third of all food produced for humans [2]. According to the United States Department of Agriculture, 31 percent of U.S food supply at the retail and consumer levels is wasted [4]. Our waste management systems face an overwhelming influx of discarded plastic products [6]. Even so-called recyclable materials have a limited number of cycles before they undergo phase separation and become unusable, meaning that recycling is not an effective solution to plastic waste [7]

Objectives

Methods

Results

Conclusion