Reactive Compatibilization of Polymer Blends

General Electric Global Research Center, Niskayuna, NY, USA 

The majority of polymer blends containing elastomeric, thermoplastic, and/or liquid crystalline polymers are processed by melt extrusion at some point in their history. After melt extrusion with intensive mixing, the morphology of an immiscible polymer blend on a microscopic scale will often consist of a dispersed phase of the more viscous polymer in a continuous matrix of the less viscous polymer (depending upon the relative amounts and viscosities of the two polymers in the blend). A good analogy from every-day experience is a dispersed mixture of viscous oil in an immiscible water matrix. 

Of the various compatibilization strategies that have been devised, an increasingly common method is either to add a block, graft, or crosslinked copolymer of the two (or more) separate polymers in the blend, or to form such copolymers through covalent or ionic bond formation in situ during the Reactive Compatibilization step. The first of these processes was described in Chapter 4 of this Handbook, Interphase and Compatibilization by Addition of a Compatibilizer, while the second method is the topic of this Chapter. 

0 wt% copolymer is sufficient to achieve morphology stabilization of an immiscible polymer blend. However, frequently higher amounts, for example as much as 10-20 wt% copolymer, may be necessary to obtain optimum physical properties of the blend, e.g., impact strength. 

The majority of commercially important, immiscible polymer blends rely for compatibilization on the presence of a copolymer of the blended polymers. Nowadays, such a copolymer is almost never synthesized in a separate step and then added as a distinct entity to the blend of immiscible polymers. Instead, a compatibUizing copolymer is most economically formed simultaneously with generation of interphase morphology during extrusion processing, a process referred to as Reactive Compatibilization. The Reactive Compatibilization process is logically a sub-category of the broader class of Interchain Copolymer Formation reactions performed by Reactive Extrusion [Brown, 1992], 

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Table 5.7. Continued Reactive Compatibilization of Polymer Blends 355... 

Reactive Compatibilization of Polymer Blends Table 5.21. Graft copolymer formation in PA/Styrene copolymer blends by amine + oxazoline reaction 371... 

Sonnier, R., Massardier, V., Clerc, L., Lopez-Cuesta, J. M., Bei eret, A., Reactive compatibilization of polymer blends by gamma-irradiation Influence of the order of processing steps. Journal of Applied Polymer Science 2010, 115(3), 1710-1717. 

Brown, S.B. Reactive compatibilization of polymer blends. In Polymer Blends Handbook, Vol. 1, Utracki, L.A., ed. Kluwer Academic Publishers, Dordrecht, 2002, Chapter 5. 

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