Polyethylene Terephthalate (PET) Recycling: Gamma irradiation impact on crystallinity, chemical structure and thermal stability

Abstract

This study explores the effects of Cobalt-60 gamma irradiation at underexplored low-doses of 0, 20, and 80 kGy on the crystallinity, chemical structure, and thermal stability of waste polyethylene terephthalate (PET). Characterization techniques, including XRD, Raman spectroscopy, DSC, and TGA, revealed that gamma irradiation modify crystallinity and thermal stability, but overall chemical characteristic is unchanging. At 20 kGy, the crystallite size increased from 59 Å to 63 Å, the melting temperature (T_m) rose from 246.2 °C to 248.4 °C, and thermal degradation and decomposition occurred 25 °C slower. XPS data showed significant chemical restructuring, with an increase in the C/O ratio from 2.89 to 4.53, indicating the breakdown of ester linkages. These findings demonstrate that optimized gamma irradiation can potentially serve as a viable pre-treatment method to improve PET recyclability, enhance crystallinity, thermal stability, and reduce energy consumption and byproduct formation in chemical recycling processes, highlighting its potential for sustainable PET waste management.