GAS PERMEATION IN POLYARYLATES - EFFECTS OF POLARITY AND INTERSEGMENTAL MOBILITY

Permeability coefficients for He, Ar, O-2, N-2, CH4, and CO2 in five polyarylates 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 the syntheses of these polyarylates were prepared by substituting one of the bridge methyl groups (-CH3) in bisphenol-A with one of the following functional groups: ethyl (-CH2-CH3), isobutyl (-CH2-CH(CH3)(2)), phenyl (-C6H5), or methyl propionate (-CH2-CH2-COOCH3). This type of substitution does not affect the polymer packing significantly. The calculated Hildebrand solubility parameter for these polyarylates also varies only in a narrow range. With these critical parameters being constant, the polyarylate permeabilities correlate well with increasing chain stiffness as indicated by secondary transition temperatures ( T(tau)degrees C). Substitutions which increased polarity had a negative effect on transport properties.