Improvement of mechanical properties of recycled PET by reactive toughening and post-crystallization

Noticeable increase in impact strength of recycled PET (RPET) was achieved using ethylene-butyl acrylate-glycidyl methacrylate (EBA-GMA) type reactive terpolymer (PTW). The decrease in stiffness and heat resistance due to reactive toughening was successfully compensated by thermal annealing. Based on the results, strong correlation can be shown between crystallinity and impact strength: increasing crystallinity results in reduced impact resistance at PTW contents higher than 5 m/m%, yet a 6-time increase compared to 100 % crystallized RPET was reached with 15 m/m% PTW content. Regarding heat resistance and stiffness, crystallinity appears to be the key parameter: above a critical value of 10 % crystallinity a sharp improvement of the properties can be noticed. Based on the results, properly choosing the elastomer ratio and post-crystallization conditions, post-consumer PET can be suitable for durable engineering applications as well.