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November 1, 2003

2 Min Read
New rigid-rod polymer jumps to market

First commercial samples of what is said to be the first thermoplastic "rigid-rod" polymer should be available this month from start-up company Mississippi Polymer Technologies Inc. (Bay St. Louis, MS). The company said in July that first grades of Parmax SRP (self-reinforcing polymers) would be for compression molding and extrusion, followed soon by the injection molding grades. MPT also anticipates applications in solvent-cast films for electronics, structural foams, coatings for aerospace, defense, electronic and specialty industrial applications, and composites.

The polymers are based on a substituted poly (1,4-phenylene). The rigid-rod backbone imparts strength and stiffness and the substituents allow melt processibility and solvent casting. Mechanical, corrosion and scratch resistance, hardness, and cryogenic properties are reportedly excellent. MPT says Parmax SRPs are strong enough for structural applications without added fibers. They are said to be two to four times stiffer and two to three times stronger than any other thermoplastic.

The polymers are not liquid crystal polymers (LCP), which are also sometimes termed rigid-rod polymers. Unlike LCPs, Parmax grades are amorphous, isotropic, and transparent. They originate in research into rigid-rod polymers sponsored by the U.S Air Force dating back to the 1960s. Early types were mostly heterocyclic (benzoxazole, thiozole) type polymers. Nick Malkovich, product development VP at Parmax, says that while they had outstanding properties, they were extremely difficult to process.

Parmax SRPs are a modification of the rigid-rod concept. While they are more soluble than classical rigid-rod polymers, "by comparison with anything else, they are amazingly solvent resistant," Malkovich says.

MTP also sees potential for the polymers in various types of composites. In blends with other polymers, small amounts (.5% to 5%) can significantly improve creep, solvent resistance, flame resistance, and mechanical properties of other polymers. Parmax SRPs can also be used as a matrix resin in long-fiber composites. Their very high modulus is expected to give composites with unprecedented compressive strength. MPT is currently developing composites and technology for producing prepregs.

Peter Mapleston [email protected]

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