Interphase and compatibilization

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. 

Blending two immiscible polymers always creates the third phase — the inteiphase. In binary blends, thickness of this third phase, AZ, is inversely proportional to the interfacial tension coefficient, When the blend approaches miscibility, approaches zero and AZ goes to infinity. Thus the interphase, with its own set of characteristic parameters e.g., viscoelasticity) may dominate the behavior of nearly miscible systems, as well as that of compatibilized blends. For further details on this topic see Chapter 4. Interphase and Compatibilization of Polymer Blends. 

It has been found in the study of PVME and SBS triblock copolymer that solubility of PVME in PS block copolymer domains is larger than in PS homopolymer. This may indicate that the mixing enthalpy has an effect on the blend miscibility [Xie et al., 1993]. The behavior has been attributed to the effect of PB segments in SBS. The phase equilibria and miscibility in polymer blends containing random or block copolymer was reviewed [Roe and Rigby, 1987]. More recent data are presented in Chapter 4 Interphase and Compatibilization by Addition of a Compatibilizer in this Handbook. 

The compatibilization must 1. Reduce the interfacial tension to facilitate dispersion, 2. Stabilize the generated morphology against modification during the subsequent processing steps, and 3. Enhance adhesion between the polymers domains, facihtating the stress transfer, hence improving the mechanical properties of the product. The methods of compatibilization are discussed in details in Chapter 4. Interphase and compatibilization by addition of a compatibilizer, and in Chapter 5. Reactive Compatibilization of this Handbook. 

Principles of polymer blends compatibilization were presented in Part 16.3.2. Details of compatibilization are discussed in Chapter 4. Interphase and compatibilization by addition of a compatibUizer, and in Chapter 5. Reactive Compatibilization of this Handbook. 

The topic is extensively treated in Chap. 4, Interphase and Compatibilization by Addition of a Compatibihzer and Chap. 5, Reactive Compatibilization , and thus only the key features are mentioned below. Several books and reviews also provide extensive information on the topic (Newman and Paul 1978 Kofliar 1981 Porter et al. 1989 Porter and Wang 1992 Brown 1992 Ajji and Utracki 1996 Datta and Lohse 1996 Utracki 1998a Bucknall and Paul 2000 Robeson 2007). 

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