Reactive extrusion controlled rheology

Fig. 11.2 The effect of the PP controlled rheology (CR) or viscracking process on the viscoelastic grid each curve represents a PP macromolecular degradation path. [Reprinted by permission from R. C. Kowalski, Fit the Reactor to the Chemistry, in Reactive Extrusion, M. Xanthos Ed., Hanser, New York, 1992.]...

Common peroxide degradants and stabilizers used in controlled-rheology reactive extrusion are shown in Table 17.2 and 17.8 of Fink (2005). 

The predominant system for controlle-rheology reactive extrusion is polypropylene (PP) with systems such as ultrahigh-melt-flow polypropylene, high-impact polypropylene blends... 

Another type of reactive extrusion is controlled degradation of PP in the presence of a peroxide initiator to give controlled rheology grade product for film applications. Typical examples of grafting reactions are ... 

Branched PBT could be produced by reactive extrusion with multifunctional epoxide in a conventional extrusion system, after some initial experiments with an intensive batch mixer. The rheology of the reactive extrusion product could be controlled by material (amount of modifier) and operational (screw rpm and feed rate) conditions. Improved foamability could be attained by the reactive modification under the optimized extrusion conditions. 

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