Process optimization of devulcanization of waste rubber powder from syringe stoppers by twin screw extruder using response surface methodology

Abstract Response surface methodology was used to predict the optimal processing parameters viz. barrel temperature and screw speed in a counter‐rotating twin screw extruder for devulcanization of rubber powder obtained from factory waste of medical syringe stoppers. Central composite rotatable design for two variables at five levels was chosen as the experimental design. The results obtained after measuring the responses were fitted as two‐variable second‐order equations. The corresponding contour plot, response surface plot, Pareto chart, and main effect plot were plotted and analyzed. Optimum properties were predicted at temperature 180°C and screw speed 27 rpm, which was confirmed experimentally. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers