Simulations of grafting monomers and associated degradation of polypropylene in a modular co-rotating twin screw extruder

Abstract

Kinetic models of grafting maleic anhydride (MAH) and methyl methacrylate (MMA) on polypropylene (PP) were developed for screw extrusion. However, the kinetic models were insufficient to explain the grafting reactions along the length of modular co-rotating twin screw extruders because the rheological properties and the residence time of PP changed owing to degradation of PP during the grafting reaction. In order to model this system for a modular co-rotating twin screw extruder, the kinetic model of grafting reaction and models for degradation of PP were combined with fluid mechanics and heat transfer. Given the geometrical configurations of the screw, the operating conditions, and the physical properties of the polypropylene, the simulations predicted variation of molecular weight and mean residence time due to degradation of PP. The weight percent of grafted MAH or MMA on PP profiles along the screw axis was also calculated in the simulation. These predictions were compared with experimental data for various operating conditions.

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

“…This model and software have been successfully developed to reactive extrusion applications. As for example, Kye and White [406] simulated the anionic polymerization of caprolactam, Kim and White [407] and Keum and White [408] successfully studied the simulations of grafting monomers and associated degradation of polypropylene. In a recent paper, White et al [409] describe a new version of their software which incorporates the ability to make devolatization calculations.…”

Kinetic study on free radical grafting of polyethylene with acrylic acid by reactive extrusion

“…Solve the chemorheological equations [eqs. (29) and (30)] to obtain the zero shear viscosity and apparent viscosity of the fluids. 5.…”

“…Numerical simulations have been devoted to reactive extrusion processes for quantitatively analyzing the reaction trend and optimizing the processing conditions . Such simulations have been performed by Motha and Seppala for the grafting of carboxylic acids and silanes to ethylene polymers, Hojabr et al for the grafting of GMA onto PE, Fukuoka for the grafting between PE and vinylsilane, Keum and White, Zhu et al, and Aguiar et al for the grafting of maleic anhydride on PP, and Zhao et al for poly[ethylene‐ co ‐(vinyl alcohol)]‐graft‐poly(Ε‐caprolactone) . With accurate numerical models, evolutions of key variables such as monomer conversion, grafting degree and fluid viscosity can be quantitatively predicted.…”

The Relevance of Multi‐Injection and Temperature Profiles to Design Multi‐Phase Reactive Processing of Polyolefins

“…In order to shed more light on the FRIG synthesis–structure relationship, several models have been proposed . One of the most detailed models is the stochastic one of Hernández‐Ortiz et al in which a monomer‐ and polymer‐rich phase are distinguished on the timescale of reactive processing (second to minute scale), with radical kinetics taking place in both phases, and corrections on the reactivities due to diffusional limitations in the polymer‐rich phase.…”