The influence of extrusion variables on the interfacial adhesion and mechanical properties of recycled PET composites

The interfacial adhesion and mechanical properties of injection-molded recycled poly(ethylene terephthalate) with glass fibre has been studied as a function of two variables involved in the extrusion process: screw speed and screw torque. The composites properties studied included DMTA, flexural strength, Young's modulus and impact strength. The Young's modulus and impact resistance of the composites increased with the addition of glass fibre in recycled PET matrix. A factorial experimental design (FED), based on the screw speed and torque of the double screw extruder used, was done to get the best thermo-mechanical properties versus processing conditions. Screw speed at the high level (200 rpm) was significant to increase Young's modulus. It was shown that “screw torque” on its high level (60%) was the significant factor to increase Impact strength of these composites. The results of these preliminary studies showed clearly the positive effect on the interfacial adhesion between matrix-fibre for some processing condition and also showed the best mechanical properties.