Physical properties of polysulfone blends

The previous section addressed miscibility issues encountered in polysulfone blends and how those relate to membrane performance. However, the functioning as a membrane is just one aspect of parts fabricated from polysulfone blends. This section of the chapter will deal with other properties, primarily mechanical properties. 

Ramiro et al studied the mechanical properties of directly injection molded specimens based on blends of poly (etherimide) (PEI) and polysulfone. The molded samples were composed of an almost pure PEI phase and a pure polysulfone phase. The measured modulus of elasticity was near to an additive relationship of the two component polymer values. The impact strength was higher than that of the poly (etherimide). The tensile strength and elongation at break were almost additive, suggesting that there is good interfacial adhesion between the two phases. The reported behavior of 

Hwang et alP have investigated mixtures of polysulfone with bisphenol A dicyanate, the structure of which is shown in Fig. 6.2. When blends with 

Those preliminary studies were later extended to include the addition of organic montmorillonite nanoscale filler to the polysulfone/dicyanate mix-tures.i The major reason for the introduction of the filler is the significant improvement in properties that can be obtained at low clay contents. The exfoliated configuration for the clay is of particular interest because it maximizes the interactions, making the entire surface of the clay layers available for interactions with the polymer matrix. This should lead to dramatic changes in mechanical and physical properties. 

In the quoted study, it was found that the polysulfone is initially miscible with the cyanate prepolymer and phase separates in spherical microdomains during the course of the cyanate polymerization process. The flexural modulus was not significantly modified by the thermo-plastic/organoclay addition. On the other hand, the fracture toughness was slightly improved with the addition of polysulfone and clay to the cyanate. 

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