PBI-polysulfone PS blends

PBI and polysulfone (PS) do not form miscible blends, but the tensile modulus and strength of their blend fibers were found to be comparable to, or better than, that of PBI fibers, depending on the process conditions. Fiber spun from 80/20 PBl-PS solution blends were found to have PBl-hke hm-iting oxygen indices (LOl) and flame shrinkage behavior. The 80/20 blend fibers were found to have comparable or superior mechanical performance to that of miscible PBl-Ultem blend fibers, and with higher modulus but lower elongation than stabilized PBI. 

It has been reported that the introduction of functional groups in the polymer chain of PS, such as sulfonate groups, can result in the formation of miscible blends with PBI. Thus, the misdbility behavior of a series of blends of PBI and suhonated PS at various suhonation levels has been studied by dynamic mechanic analysis (DMA), FTTR, and FT-Raman spectroscopy. Partially miscible or miscible blends were obtained when the sulfonation level was higher than 10 mol%. FTIR band shifts associated with the N-H and sulfonate groups were shown to account for the induced misdbiUty in terms of specific interactions. Also, preliminary results were shown to 

Sulfonation of PS has been found to cause moderate increases in the from 190°C to 210-225°C, and with the PBI-sulfonated PS miscible blend exhibiting excellent miscibility characteristics based on the hydrogen bonding between the N-H group of PBI and the sulfonated groups of the PS. Thermal stabihties at over 200°C were achievable, and the miscibility was found to be dependent on the PBI-sulfonated PS ratio as well as the degree of sulfonation.  

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