Polysulfones thermoset mixtures

These conclusions imply that fundamental studies of the phase separation process in polysulfone/thermoset mixtures are needed to better understand the kinetics of the situation. General conclusions about the range of variables that allow for the development of a certain morphology compared to others are needed to be able to take full advantage of the fracture toughness enhancements that have been observed in certain polysulfone/thermoset mixtures. It is through such an understanding that the optimum polysulfone/thermoset mixture can be defined and developed. 

When mixtures with less than 10 wt% were cured isothermally, they were phase separated due to a nucleation and growth mechanism. On the other hand, with more than 20 wt% polysulfone, the blends were phase separated by spinodal decomposition. These different mechanisms are important because in thermoset/thermoplas-tic blending, the fracture toughness is determined by the morphology that is formed as a consequence of the phase separation. 

The general term polysulfone describes an entire family of thermoplastic polymers which are melt processable. The polymers are particularly known for their toughness and stability at high temperatures. They contain the subunit aryl-S02-aryl, the defining feature of which is the sulfone group. This chapter will discuss blends of polysulfone polymers with other polymers, both thermoplastics and thermosets, and the results obtained from the production of such mixtures. 

Polymer features that lead to miscibility with polysulfone should be further quantihed to be able to optimize the membrane separation characteristics of polymer mixtures. On the other hand, in the case of immiscible polysulfone blends, it is desirable to better define the features of the blend components that lead to a particular morphology. Some of those features are perhaps going to be different in the case of thermoplastic and thermoset matrix materials, but viscosity is certainly going to be relevant in both cases. However, in order to best utilize the polysulfone blends that have been discussed in this chapter, more work is required to better comprehend their structure-property-processing relationships. 

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