Electrical, Mechanical, and Thermal Properties of Poly(4,4'-Cyclohexylidene Diphenylene-m-Benzene/Toluene-2,4-Disulfonate)

The films of poly(4,4'-cyclohexylidene diphenylene-m-benzene disulfonate) (PSBB, 0.610 mm thick) and poly(4,4'-cyclohexylidene diphenylene-toluene-2,4-disulfonate) (PSBT, 0.537 mm thick) showed 8.23 ± 0.25 and 9.6 ± 0.245 kV, respectively, as the dielectric breakdown voltage (ac) in air at room temperature. The same films have 8.8 × 1011 and 7.2 × 1014 ω°Cm volume resistivity. PSBB (40 μm thick) and PSBT (50 μm thick) films have tensile strengths of 1971 and 1677 kg/cm2 and percent elongations of 1.3 and 1.2, respectively. The static hardnesses of PSBB (0.178 mm thick) and PSBT (0.190 mm thick) at three different loads (15-60 g) are 12.8-15.5 and 14.5-16.5 kg/mm2, respectively. PSBB and PSBT are thermally stable up to about 355°C in an N2 atmosphere and involve two-step degradation. DSC and DTA showed Tg at about 125-127 and 138-142°C, respectively, for PSBB and PSBT in N2. PSBB and PSBT have comparable breakdown voltages and volume resistivity with some useful plastics whereas they have superior Tg and thermal stability with retention of excellent solubility in common solvents over polysulfonates without a cardo group. Thus, the cardo (cyclo-hexyl) group has enhanced thermal and mechanical properties with excellent solubility and easy processing.