The working domain in reactive extrusion. Part I: The effect of the polymer melt viscosity

Abstract

This article describes the radical copolymerization of styrene (St) and n‐butyl‐methacrylate (BMA) in a counter‐rotating twin‐screw extruder. In order to investigate the effect of the polymer melt viscosity on the working domain in reactive extrusion, the copolymer was crosslinked with different amounts of divinylbenzene (DVB). Crosslinking of the polymer resulted in a higher polymer melt viscosity. It was demonstrated that not only the product properties but also the process characteristics were strongly influenced by the addition of divinylbenzene to the reaction mixture. The product properties changed as expected: more crosslink agent led to a higher molecular weight or an increase in gel fraction, and a much higher melt viscosity of the polymer. Besides these effects on the product properties, the addition of DVB resulted in a more stable process, leading to an enlarged working domain.

Reactive extrusion of poly(urethane‐isocyanurate)

“…The polymer melt viscosity influences both the throughput and the stability of the process. 24 The average viscosity of the reaction mixture during the synthesis of PUIR is a function of reaction and process parameters. When fixed values of N and T are chosen, it is possible to construct a working domain for the reactive extrusion of PUIRs in terms of r and C. • C. At low values of r and C, the product was in a viscous liquid state, due to lower extent of reaction.…”

“…The fact that highly crosslinked polymers lose their thermoplastic properties may make the extruder not suitable for processing of these materials. 24 In the reactive extrusion of PUIRs, the degree of crosslinking, which is a function of several parameters including r -value, catalyst concentration, and temperature profile should be controlled so as to keep its processability in the extruder. The reactively extruded samples 1 and 2 were granulated in order to examine their further processability.…”

Computer simulation of reactive extrusion processes for free radical polymerization

“…To describe the rheological property of the steady-state flow of incompressible non-Newtonian fluids, the powerlaw constitutive equation is adopted in this paper [19,31]…”

Polymer Blend Compatibilization by Copolymers and Functional Polymers

“…Consequently, shear rate levels are moderate and so is the dispersion efficiency. Copolymerization of styrene--butyl methacrylate, polymerization of e-caprolactam, grafting of maleic anhydride onto polyethylene, polymerization of urethanes, and radical polymeriza tion of methacrylates are examples of reactions performed using this machine [142]. Non-intermeshing counter-rotating extruders are utilized for polycondensation reactions, as they provide excellent distributive mixing even at low shear rates, but they have limited pressure generation capacity and dispersive mixing efficiency.…”