GAS PERMEATION IN POLYARYLATES - EFFECTS OF POLARITY AND INTERSEGMENTAL MOBILITY

Permeability coefficients for He, Ar, O-2, N-2, CH4, and CO2 in five p olyarylates synthesized from a mixture of iso:terephthalic acids (1:1) and a bridge substituted bisphenol were measured at a pressure of 1.0 x 10(6) N/m(2) and temperature of 35 degrees C. Bisphenols used for t he syntheses of these polyarylates were prepared by substituting one o f the bridge methyl groups (-CH3) in bisphenol-A with one of the follo wing functional groups: ethyl (-CH2-CH3), isobutyl (-CH2-CH(CH3)(2)), phenyl (-C6H5), or methyl propionate (-CH2-CH2-COOCH3). This type of s ubstitution does not affect the polymer packing significantly. The cal culated Hildebrand solubility parameter for these polyarylates also va ries only in a narrow range. With these critical parameters being cons tant, the polyarylate permeabilities correlate well with increasing ch ain stiffness as indicated by secondary transition temperatures ( T(ta u)degrees C). Substitutions which increased polarity had a negative ef fect on transport properties.