Reactive extrusion processing

Compatibilization during reactive processing, extrusion or injection molding. 

Figure 4.32. Two-section single screw extrusion unit for reactive processing.

Figure 4.35. Extrusion die for reactive processing with a gap (of the width a) for injecting a lubricant.

Figure 4.36. Extrusion die for reactive processing with an interchangeable sleeve (for an explanations of the numbers see text).

C.G.Gogos, From Compounding to Micro-structuring to Reactive Processing, Keynote Lecture, Extrusion Division, Proc. 55th Soc. Plastics Eng. Ann. Technical Conf, Toronto, Canada 1997. 

An excellent source of references on reactions carried out in polymer processing equipment is S. B. Brown, Reactive Extrusion A Survey of Chemical Reaction of Monomers and Polymers, during Extrusion Processing, in Reactive Processing, M. Xanthos, Ed., Hanser, Munich, 1992. 

The success of RIM has spurred interest in other means of reactive processing. Reactive extrusion and reactive blending are two related processes with interesting potential. Reactive extrusion refers to processes in which... 

The addition of peroxides, R OOR", during reactive processing has become a routine aspect of reactive extrusion technology for polypropylene and polyethylene (Xanthos, 1992). In particular, the dialkyl peroxides at a level ranging Ifom 0.001 to 1 wt.% have been used and have half-lives ranging Ifom 1 to 3 minutes at 180 C, so 99% consumption will occur in 7-20 minutes at that temperature. The reaction steps depend on whether oxygen is present... 

In reactive processing, such as reactive extrusion of thermoplastics, the use of DSC may be seen in determining the stability of the polymer formulation by measuring the oxidation induction time (OIT) (Bair, 1997). This is an isothermal experiment in the presence of air... 

The term reactive processing is used to describe a polymer processing that involves chemical reactions. In principle, any processing operation can be conducted as a reactive process, viz. reactive injection molding (RIM). However, most often the term refers to reactive extrusion, and in particular, to the reactive compatibilization of immiscible polymer blends, usually conducted in a TSE. During the last 50 years, the latter machines have been used as chemical reactors for the polymerization, depolymerization (chemical recycling), polymer modification and compatibilization [Brown, 1992, Xanthos, 1992 Utracki, 1989, 1991, 1994, 1997]. 

Execution of chemical reactions during extrusion of polymers and/or polymerizable mmiomers. The reactants must be in a physical form suitable for extrusion processing. Reactions have been performed on molten polymers, on Uquefied or dispersed monomers, or on polymers dissolved or suspended in or plasticized by a solvent (also reactive compounding or reactive processing). 

Reactive processing n. A molding or extrusion operation in which chemical reactions are carried out. Extruders, mainly specialized twin-screw machines, have successfully carried out partial and complete... 

For reactive processing it is convenient to combine rheological data with the chemical kinetics of the reaction and to express the viscosity as a function of the conversion or, even more convenient in reactive extrusion, as a function of time. 

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