Contribution of compatibilizer backbone to degradation and retained functionality of multiple extruded polypropylene/poly(ethylene terephthalate) blends

This study assesses thermal and morphological stabilization of three compatibilizers during mechanical recycling of polymer blends. Polypropylene/poly(ethylene terephthalate) blends compatibilized with three different maleic anhydride grafted compatibilizers were extruded five times via single-screw extrusion. The backbones of the compatibilizers are (1) polypropylene-based, (2) an elastomer block copolymer poly(styrene-co-[ethylene-butylene]-styrene), and (3) a polyolefin elastomer. The degradation and retained functionality of these compatibilizers was assessed by means of simultaneous thermo-gravimetric analysis, melt flow index, a morphology study, differential scanning calorimetry and tensile testing. The results show that degradation of the compatibilized blends during multiple processing is low, although the core stability of the blends depends on the initial stability of all of the components in the blend. The thermal stability across the five extrusions was the most favorable for the matrix based grafted compatibilized blend. The functionality of the compatibilizers did show minor morphological destabilization but did not affect the mechanical properties.

Automated summary

The study evaluates the thermal and morphological stabilization of three compatibilizers during the mechanical recycling of polymer blends. The results show that although the degradation of the blends is low during multiple processing, the core stability depends on the initial stability of all components. The thermal stability of the matrix-based grafted compatibilized blend is the most favorable across the five extrusions.