Effect of Antioxidants and Compatibilizers on Gel Formation and Film Quality of Polyethylene Films With Recycled Content

ABSTRACT Adding recycled content is paramount for achieving circular packaging. However, packaging films produced from postindustry or postconsumer recycled polyethylene (PCR PE) have been reported to have various visual and mechanical issues related to impurities and degradation, which affect their performance. This paper studies the gel presence and seal characteristics of packaging films produced from 100% monolayer PCR PE with the addition of antioxidants and compatibilizers. It additionally evaluates the performance of commercially produced multilayer PE films that contain 30% and 50% PCR PE in the core layers and virgin sealant and top layers, checking the quality variations that arise from the difference in PCR PE batches. In the research, the presence and surface area ratio of gels related to recycled content are analyzed using FTIR, microscopy and a newly introduced image analysis method; seal performance is measured via hot‐tack and cold‐tack tests, and material performance is evaluated via tensile testing. According FTIR findings, some spherical and fibre like impurities coming from PCR PE were found to be polyamide or cellulose based, respectively. In nonfood contact commercial films with PCR PE content, the quality varied largely from batch to batch as well as the hot and cold seal strength. In 100% PCR PE films produced in laboratory settings, adding antioxidants during film production did not significantly influence the gel presence while one of the maleic anhydride‐based (MAH) compatibilizers used in the research reduced both the gel number (from 432 to 375 pcs/9 cm 2 ) and gel area ratio (from 0.81% to 0.67%). On the other hand, both types of additives delayed the breakage failure providing a larger operation window in hot‐tack tests. During the cold‐tack test, stronger attachment at the seal interphase is observed at 100°C sealing temperature in samples with added compatibilizer. Finally, according to tensile test results, the Young's modulus and the elongation at break only showed slight changes with the addition of antioxidants and compatibilizers. The results can be used for guidelines for design from recycling working with PE films.