Compatibilization by Addition of a Compatibilizer

National Research Council Canada, Industrial Materials Institute, Boucherville, QC, Canada 

The surface tension is the reversible work required to create a unit surface area at constant temperature (T), pressure (P) and composition (n) [Wu, 1982]  

The structure and morphology of immiscible blends depends on many factors among which the flow history and the interfacial properties are the most important. At high dilution, and at low flow rates the morphology of polymer blends is controlled by three dimensionless microrheologi-cal parameters (i) the viscosity ratio, where r j is the viscosity of the dispersed liquid and r 2 that of the matrix (ii) the capillarity number, k = d / Vj2, where d 

In this chapter, compatibilization of polymer blends by means of addition of a compatibilizer will be discussed. First, the theories will be summarized of the (i) interface, (ii) interphase, and (iii) compatibilization process. This brief summary is to provide a general framework for understanding the phenomena associated with compatibilization, and guidance for optimization of the process to gain maximum performance. 

The theoretical part is followed by the experimental part, where the methods for the determination of interfacial properties are presented. Most of the chapter is dedicated to provide comprehensive information on the characteristic properties of blends compatibilized by addition of a compatibilizing agent. 

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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. 

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. 

Introduction to polymer blends, 2. Thermodynamics, 3. Crystallization, 4. Interphase and compatibilization by addition of a compatibilizer,... 

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