POLY(p-PHENYLENE SULFIDE)—AN OVERVIEW OF AN IMPORTANT ENGINEERING THERMOPLASTIC

Abstract Among the various high temperature polymers, those based on aromatic units, such as poly(2, 6-dimethylphenylene oxide) (PPO), poly(pheny1ene sulfide) (PPS), poly(ether ether ketone) (PEEK), and poly(ether sulfone) (PES), have attracted much attention in the last few years due to their good thermal and chemical resistance. One of these polymers, PPS, is also an important high strength/high temperature engineering thermoplastic that is finding increasing use in technological applications such as molding resins, fibers, and matrices for thermoplastic composites. PPS consists of para-phenylene units alternating with sulfide linkages. The first known report of its synthesis was by Grenvesse in 1898 [1]. However, interest in the synthesis of PPS only began in 1948 when Macallum 121 described the preparation of phenylene sulfide polymers by the melt reaction of p-dichlorobenzene with sodium carbonate and sulfur. Further investigation on the synthesis of PPS by Lenz and coworkers [3–5], and later by Edmonds and Hill [6], developed PPS into a commercial reality. After synthesis, the polymer is an off-white powder that has a glass transition tem- perature (T) at 85°C and melting point at about 285°C. The B 3+ off-white coloration is known to be due to the presence of Fe ions in the forms of FeCl that arise from the steel reactor 3 utilized to synthesize PPS. However, this problem can be avoided by utilizing a titanium reactor. Therefore, "white" or purer polymer can be obtained [7]. The study of the structure and molecular weight distribution of PSS has been precluded by its intrinsic high chemical resistance. Only recently, a gel permeation chromatographic system (GPC) capable of determining molecular weights and molecular weight distribution of PPS has been developed [8]. The GPC exyeriments are conducted utilizing a-chloronaphthalene as the solvent at 21°C in order to maintain PPS in solution. Typical polydispersity ratios of PPS synthesized by the method of Edmonds and Hill are in the order of 1.5–2.0.