Recycling of postconsumer poly(ethylene terephthalate) and high‐density polyethylene by compatibilized blending

Abstract

Two ways of recovering the properties of the scrap plastics poly(ethylene terephthalate) (PET) and highdensity polyethylene (HDPE) were analyzed: (1) blending incompletely segregated polymers with a compatibilizer and (2) blending nonsegregated polymers with a small amount (2 pph) of another compatibilizer. The advancement of the compatibilization reaction in a twin-screw extruder depended on the residence time and intensity of mixing according to melt viscosity measurements and scanning electron microscopy observations. The acceptable mechanical properties for systems with different PET contents were obtained in blends compatibilized with ethylene-glycidyl methacrylate (EGMA) and styrene-ethylene-butylene-styrene grafted with maleic anhydride. For a blend with 75% PET and 25% HDPE, the optimum content of EGMA was determined to be about 4 pph, and a film was produced with this composition. Admixtures present in recycled HDPE migrated to PET during blending and accelerated the hydrolysis of PET. As a result of migration, differences in the mechanical properties of the blends were observed, depending on the brand of recycled HDPE used. EGMA was also successfully used for the improvement of mechanical properties of a nonsegregated mixture based on PET. Tensile properties of two compatibilized PET-rich and HDPE-rich commingled scraps indicated the possibility of using these blends for film extrusion, with potential applications in the packaging of technical products.

Influence of Blend Composition and Compatibilizer on Mechanical and Morphological Properties of Recycled HDPE/PET Blends

“…Meanwhile, the compatibility of the blends with 7.5 php is worse than that of blend with 5 php as observed in SEM images. This indicates that a higher content of E-GMA may generate the crosslinking of HDPE and worsen the blend properties [10]. Therefore, it can be concluded that the amount of compatibilizer used should have an optimal limitation [21], between 5 and 7.5 php in this study.…”

“…Of all the compatibilizers used in HDPE/PET blends, reactive functional groups of maleic anhydride (MA) and glycidyl methacrylate (GMA) are the most common. Graft copolymer containing MAs such as MA grafted polyethylene (PE-g-MA) [4] [7] [9], HDPE-g-MA [10] and MA grafted styrene-ethylene-butenestyrene copolymer (SEBS-g-MA) [9] [10] have been reported. Whilst, random copolymer containing GMA such as HDPE-g-GMA [10], E-GMA [9] [11], ethylene-ethyl acrylate-glycidyl methacrylate (E-EA-GMA) [11] and ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) [12] are commonly used for investigation.…”

Recycling of Polymer-Based Multilayer Packaging: A Review

“…Nonetheless, the strategies described are similar to the methods mentioned before, and mostly polyolefin-based compatibilizers grafted with anhydrides or acids can be found [102][103][104][105].…”

Phase structure and properties of poly(ethylene terephthalate)/high‐density polyethylene based on recycled materials

“…7 Pawlak et al found that though the mechanical properties of R-PET rich blends were markedly improved by adding E-GMA, better performance was obtained with SEBS-g-MA in R-PE rich blends. 8 Carté et al produced a PET/ PE (50/50) blend containing 20 pph (part per hundred) SEBS-g-MA exhibiting a twofold increase in elongation at break relative to PE. 9 Functionalized polyolefins with reactive groups such as maleic anhydride, acrylic acid, and glycidyl methacrylate, can also effectively enhance the morphology and physical/mechanical properties of R-PET/R-HDPE blends.…”