For reactive blending

Due to the excellent price/performance ratio, polypropylene should not only be a good base for unreactive blends, widely used in automotive industry, but also an attractive product for reactive blending. However, it is necessary to introduce polar reactive groups in the main chain which is difficult... 

The formation of compatibilizer frequently occurs by interfacial reaction of the modified polymers. An example is the use of maleic anhydride grafted to a polyolefin elastomer (EPM/EPM-g-MA) as the interfacial additive for reactive blending with a polyamide, nylon-6 (Van Duin et al., 2001), in a twin-screw extruder. It was found that the consumption of MA occurred rapidly and different blend morphologies were produced. However, it was found that the nylon-6 degraded during processing, due to the reaction of anhydride with the... 

In non-reactive blending, a two- (or multi-)phase mixture is formed when the immiscible polymers are physically mixed with each other. The minor phase, rich in B, is dispersed as droplets into a major phase rich in A. Apart from low interfadal tension, high shear rates and similar viscosities of both polymers are important for the size of the dipersed phase and therefore for the product quality. The reactive route follows the synthesis of a minor component via polymerization into a major component that acts as a host polymer. An alternative route for reactive blending is in situ formation of block co-polymers during the mixing process to decrease the interfacial tension. An extruder is the most commonly applied apparatus for the continuous production of polymer blends. 

It is expected that many novel and useful polymer blends will be obtained using supercritical CO2 by applying both the reactive as well as the non-reactive route, and an extruder may well be a good choice of equipment for reactive blending in the continuous production of various polymer blends. 

Excellent reviews for reactive blending and reactive compatibilization have been given by Baker et al. [4]. 

Figure 4.1 Reactive groups of interest for reactive blending...

Despite its great scientific interest and crucial importance for reactive blending, reaction kinetics at polymer-polymer interfaces remains poorly understood. From an experimental viewpoint, two types of experiments can be envisioned ... 

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