Numerical analysis of a reactive extrusion process. Part I: Kinetics studyon grafting of vinylsilane to polyethylene

For controlling a reactive extrusion process in the subsequent study, the m odel equations of reaction kinetics and shear viscosity were studied. We fo cused on a free radical reaction between the molten polyethylene and vinyls ilane. The kinetics model was expressed as a reaction rate equation with an apparent rate constant. The shear dependent of reacted polyethylene was fo rmulated by employing the modified Cross model proposed in our early study; In addition, the average molecular weight was considered to correlate the shear viscosity with the reaction kinetics, leading to a series of rheo-kin etics formulas. The experiments were carried out in a specific batch mixer suitably designed for sampling in arbitrary periods. Their reaction convers ions, molecular weight distributions, and shear viscosity were measured, re spectively, with an induced coupled plasma (ICP) emission spectrochemical a nalyzer, a high temperature gel permeation chromatography (GPC), and a capi llary rheometer. Determining the parameters in each model, a simulator is s et to investigate an engineering extrusion process.