PP fiber replaces glass in thermoset composites.

A high-modulus PP fiber with the same strength as fiberglass and one-third the density has been developed as a lightweight reinforcement for thermoset composites. PP fibers have already found a place in composites, consolidated into "self-reinforced," all-PP tapes and sheets. But new Innegra PP fiber is claimed to be the first PP fiber suitable for reinforcing thermoset resins.

Supplied by start-up Innegrity LLC in Greer, S.C., Innegra fiber has a density of 0.9 g/cc, vs. 2.5 g/cc for glass. Its toughness is said to be twice that of Kevlar aramid fiber. Innegra also has superior dielectric properties (dielectric constant of 2.2 vs. 6.2 for glass), suiting it to high-frequency electronics. It also boasts high chemical resistance. Optimum composite properties are said to be achieved in hybrid composites combining Innegra with glass, aramid, or carbon fibers. In a composite using 50% glass and 50% PP fiber, weight is 30% less than with all-glass reinforcement. The fibers can be plasma treated for adhesion to thermoset resins.

Two fiber types are being developed: Innegra S, optimized for strength, and Innegra E, with improved dielectric properties for aircraft radomes and circuit boards. The PP fiber costs roughly twice as much as fiberglass but less than aramid or carbon. The first production line with a capacity of I million lb/yr has started up in Greer and another two lines will be added over the next two years, the company says. There are no commercial applications as yet. The company is focused on aerospace, marine, and electronics. Among the first commercial applications expected this year are circuit boards and medical cast and splint supports. Tel: [phone] * www.innegrity.com

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