Influence of polymerization conditions on the molecular structure stability and physical behavior of poly(phenylene sulfide sulfone) homopolymers

The influence of polymerization conditions on the nucleophilic substitution step polymerization of high molecular weight poly(phenylene sulfide sulfone) (PPSS) has been studied and optimized with respect to molecular weight for the system 4,4'-dichlorodiphenylsulfone, sodium sulfide, NMP/water/sodium acetate. Reactions at about 200 degrees C for 3 h were observed to produce the highest molecular weight. Longer reaction times and/or higher temperature degrade the molecular weight, probably because of base-catalyzed reactions on the activated backbone. These polymeric materials are amorphous with T-g values up to 222 degrees C. However, the systems show some ordering in the presence of organic liquids, and this allows for an unexpectedly high degree of solvent resistance for molded films. The materials also show a high refractive index of 1.69 and cone calorimetry showed the PPSS system to have very good fire resistance. (C) 2000 Elsevier Science Ltd. All rights reserved.