An approach on reactive processing of plastic waste

An approach on the reactive processing and compatibilization of plastic waste was simulated for the mixture of thermoplastics with the major content in municipal plastic waste: low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, poly(vinyl chloride) (PVC), polyethylene terephthalate, polymethyl methacrylate, PA6, and acrylonitrile-butadiene-styrene. Peroxide initiators 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (L101) and hydrogen peroxide (H2O2) and poly(styrene-b-ethylene-b-butylene-b-styrene) grafted with maleic anhydride (SEBS-g-MAH) were used for the reactive processing of polymer blend under optimized conditions (concentration, reaction temperature, and time). The compatibilization was evidenced by “online” monitoring of the melt viscosity during reactive processing of polymer blend and examined by melt volume rate, oscillatory rheology, mechanical testing, and scanning electron microscopy. The effect of selected peroxides on the type of radical reaction was also evidenced for individual thermoplastics. Both L101 and hydrogen peroxide modify the melt viscosity with different effectivity due to different miscibility, decomposition mechanism, and limited reactivity of individual thermoplastics toward primary radicals. Therefore, the efficiency of compatibilization is limited. On the other hand, SEBS-g-MAH acts is an “universal” and effective reactive compatibilizer for multicomponent polymeric blend due to combination of covalent and non-covalent interactions with blended thermoplastics, resulting in the improvement of mechanical properties and morphology of polymer blend.