Reactive Extrusion of Recycled Polycarbonate Using Chain Extenders

Abstract

Electronic waste (e-waste) problem becomes more critical due to increasing demand on upgrading of electrical-electronic devices in accordance with the latest technology nowadays. Polycarbonate (PC) is one of the most used plastics to produce computers, mobile phones and televisions thus recovering of PC wastes to develop new value-adding products has been an important task. The challenge of the PC recycling is thermal degradation under multiple thermo-mechanical processing cycles, which deteriorates molecular weight and properties of the polymer. In this study, a multi-functional anhydride chain extender (ANHY) and a multi-functional epoxy chain extender (EPOX) were used to offset thermal degradation of recycled PC (rPC) during extrusion. The effect of chain extenders on the properties of resulting materials was evaluated by rheology, tensile test, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Both types of chain extenders enhanced the viscoelastic and mechanical properties of rPC, however ANHY had much higher chain extension reactivity than EPOX. ANHY increased complex viscosity by 58% and tensile modulus by 39%, whilst EPOX showed 26% increment in complex viscosity and 10% enhancement in tensile modulus on the base rPC. The formation of long chain branching in the samples containing chain extenders was observed from the rheology tests. TGA results also confirmed the efficiency of ANHY chain extender that shifted decomposition temperature of rPC to higher value than that of EPOX. The incorporation of chain extenders slightly increased glass transition temperature (T-g) of rPC in DMA and DSC test results.