Polyphenylene sulfide linear

Aromatic cyclic chains are more stable than aliphatic catenated carbon chains at elevated temperatures. Thus linear phenolic and melamine polymers are more stable at elevated temperatures than polyethylene, and the corresponding cross-linked polymers are even more stable. In spite of the presence of an oxygen or a sulfur atom in the backbones of polyphenylene oxide (PPO), polyphenylene sulfide (PPS), and polyphenylene sulfone, these polymers are... 

Sulfar fibers are extruded from polyphenylene sulfide) or PPS by the melt-spinning process. The first PPS polymer was made in 1897 by the Friedel-Crafts reaction of sulfur and benzene. Researchers at Dow Chemical, in the early 1950s, succeeded in producing high-molecular weight linear PPS by means of the Ullmann condensation of alkali metal salts of p-bromothiophenol. 

Lenz RW, Handlovits CE, Smith HA. Pheny-lene sulfide polymers. III. The synthesis of linear polyphenylene sulfide. J Polym Sci 1962 58(166) 351-67. 

Engineering thermoplastic resins (ETP) are those whose set of properties (mechanical, thermal, chemical) allows them to be used in engineering applications. They are more expensive than commodity thermoplastics and generally include polyamides (PA), polycarbonate (PC), linear polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyphenylene ether (PPE) and polyoxymethylene (POM). Specialty resins show more specialized performance, often in terms of a continuous service temperature of 200°C or more and are significantly more expensive than engineering resins. This family include fluoropolymers, liquid crystal polymers (LCP), polyphenylene sulfide (PPS), aromatic polyamides (PARA), polysulfones (P ), polyimides and polyetherimides. 

He reported that polymers prepared in this manner generally contained more than one sulfur atom per repeat unit (x in the range 1.2-2.3). In addition the polymerization reaction was highly exothermic and difficult to control, even on a small scale.7 Certainly Macallum s work sparked an interest in polyphenylene sulfide (PPS) and triggered a series of investigations that eventually led to the commercial production of PPS. In 1954 Macallum sold his patents to Dow Chemical Co. where this polymerization scheme was studied further. However, the problems associated with the severe polymerization conditions and control of the exothermic reaction remained largely unsolved.9 Lenz and coworkers at Dow have studied the mechanism of the Macallum polymerizationlO and the structure of the polymer produced, ii The structure postulated consists of a crosslinked core to which are attached more or less extended, linear chains. 

This laboratory process provided a linear polyphenylene sulfide material. Considerable difficulty was encountered in removing the by-product, copper bromide, from polymers made by this proeess.l3 This difficulty became more formidable on attempted scale-up and PPS was never produced commercially by Dow. 

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