Numerical simulation of effects of operating conditions on the molecular weight of polypropylene using a response surface method

A L4635 Box-Behnken design was used for developing a model to predict and optimize the molecular weight(Mw)of polypropylene(PP);a second-order polynomial regression equation was derived to predict responses.The significance of variables and their interactions were tested by means of the ANOVA with 95% confidence limits;the standardized effects were investigated by Pareto chart,the optimum values of the selected variables were obtained by analyzing the response surface contour plots.The optimized Mwvalue of 1.217×105 g/mol was very close to the industrial value((1.22±0.004)×105 g/mol)at the optimum values.