Phenylene polysulphide PPS - Economic aspects

PPS (polyphenylene sulfide) was introduced in 1968 and was initially used mainly in aircraft construction.

PPS, developed by Dr. H. Wayne Jr. Hill and Mr. James T. Edmonds Phillips Petroleum Co, was launched commercially in 1973 by Phillips, under the name Ryton, whose patents fell into the public domain in 1987.

PPS is a crystalline polysulfide consisting of a chain of benzene rings linked by a sulfur atom. It is obtained by reacting paradichlorobenzene with sodium sulfide, in a polar solvent such as N-methylpyrrolidone, which is stable at the high temperatures required for synthesis and also solvent for intermediate oligomers.

The product obtained directly is a low-molecular-weight PPS, well-suited to use as a coating. However, to mold it, the PPS must be heated in oxygen, to obtain a higher molecular weight. This also produces a cross-linked PPS.

The PPS can take different forms:

• powder, especially for coatings ;

• cross-linked, with improved thermal and dimensional stability, for coatings and injection molding;

• linear, one-step product with improved impact resistance, for injection compounds;

• modified, especially for film extrusion.

PPS is usually reinforced with glass fibers (usually 40 to 65%), carbon fibers, or filled with mineral fillers, talcum powder, etc.