Polymerization behavior of PPS, PBS, and PPSE and thermal properties

Poly(p-phenylene sulfide) (PPS), poly(p-biphenylene sulfide) (PBS), and poly (p-phenylene sulfide ether) (PPSE) were synthesized from sodium sulfide and p-dichlorobenzene, 4,4'-dibromobiphenyl, and 4-bromophenyl ether, respectively, using N-methyl pyrrolidinone (NMP) as solvent under high temperature(greater than or equal to 250 degrees C) and pressure (greater than or equal to 150psi). From the study of reaction conditions, the optimum reaction temperatures were found to be increased in the order of 250 degrees C <270 degrees C <290 degrees C for the synthesis of PPS, PBS, and PPSE. All these polymer forming reactions showed less influence on stoichiometric imbalance of corresponding monomer ratios than normal polycondensation reactions such as polyesterification or polyamidation. The effect of water as an additive in the NMP solvent was found to give maximum yields of all three polymers at [H2O]/[sodium sulfide]=9:1 level. The copolymerization behavior of PPS/PBS and PPS/PPSE combination was also studied according to the optimum homopolymerization reaction conditions. The molecular weights of polymers were determined by the high temperature(210 degrees C) GPC with 1-chloronaphthalene as eluent. Thermal analysis (DSC) of polymers showed T-m=279 degrees C, 195 degrees C for PPS and PPSE, respectively. The thermal stability of polymers was found to be increased in the order of PPSE<PPS<PBS from the TGA measurement.