Issues in blending polysulfone with other high temperature polymers

3 Issues in blending polysulfone with other high temperature polymers 

Following up on the comments from the last section, the first blends to be discussed will be blends of PBl with polysulfone. In an initial investigation of these blends, Chung et al determined that the two polymers do not 

It was later shown that the introduction of functional groups, such as sulfonate groups, into the polysulfone polymer entity resulted in the formation of miscible blends with PBI. Further, the degree of sulfonation as well as the overall blend composition controls the observed miscibility behavior. Fourier Transform (FT-IR) Analysis showed that the observed miscibility is due to spedfic interactions between the N-H group on the PBI and the sulfonate groups on the polysulfone. 

Similar observations have been made of blends of polyamide 11 (PA 11) and sulfonated polysulfone (SPSF) prepared by solution casting from dimethyl formamide (DMF). In that work, differential scanning calorimetry (DSC) showed a melting point depression of the equilibrium melting point of the PA 11, indicative of an interaction between the two polymers. With lower degrees of sulfonation of the polysulfone, less interaction between the two polymers was observed. FT-IR and Raman spectroscopic techniques were used to confirm the nature of the specific interactions involved. 

In EP 0778077A3, gas separation polymer membranes were prepared from mixtures of polysulfone, Udel P-1700, and an aromatic polyimide, Matrimid 5218. The two polymers were proven to be completely miscible as confirmed by optical microscopy, glass transition temperature values and spectroscopy analysis of the prepared mixtures. This complete misdbility allowed for the preparation of both symmetric and asymmetric blend membranes in any proportion from 1 to 99 wt. % of polysulfone and polyimide. The blend membranes showed significant permeability improvements, compared to pure polyimides, with a minor change in their selectivity. Blend membranes were also more resistant to the plasticization phenomenon compared with pure polyimides. This work showed the use of polysulfone-polyimide blends for the preparation of gas separation membranes for application in the separation of industrial gases. 

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