New Polymer Designed to Take the Heat

By Brown, Alan S

GE Plastics has launched a new family of high-temperature engineering resins. The new polymers, branded Extern, combine outstanding heat resistance with very good processability, the company says. Potential applications range from semiconductor wafer handling and oil and gas processing to aerospace, automotive, and electronics manufacturing.

Extern is a high-heat, amorphous, melt-processable thermoplastic polyimide that users can run in conventional molding equipment now running other engineering resins, according to GE’s global product manager, Rob Costella. It performs well from below zero to a continuous- use temperature of 230C.

According to GE, the material’s amorphous nature gives it good dimensional stability, creep resistance, and strength at elevated temperatures (although these properties fall off sharply as it nears its 311C glass transition temperature, where it turns soft and rubbery). The amorphous structure resists chemicals, especially chlorinated solvents. It is also inherently flame retardant.

Extern is rated for 50C higher continuous-use temperatures than is GE’s Ultem melt-processible resin. Ultem does not stand up as well as Extern does to chlorinated solvents and other chemicals. GE claims that Extern retains its strength and stiffness above 200C better than polyetheretherketone or polyethersulfone.

Solvay Advanced Polymers’ Torlon polyamide-imide has better heat resistance, but usually needs annealing for prolonged periods following melt processing. It is often machined from solid blocks.

“There are only so many people who can process Torlon,” Costella said. “Our customers usually can’t bid on those applications because they can’t meet the heat profile. With Extern, they can offer an injected molded part or stock shape that meets those requirements.”

Starting in the first quarter, GE will offer two Extern grades. The first, Extern UH, has the higher glass transition temperature (311C) and better chemical resistance. Extern XH has a lower glass transition (267C), but better flow and creep resistance. GE will make both materials available in glass and mineral-reinforced grades.

GE says the two grades are the start of a family of as many as 75 new Extem grades. By blending Extern with PEEK, PES, Ultem, and other engineering resins, the company hopes to be able to produce resins with price and performance optimized for specific applications.

GE Plastics says its new Extern resin performs well to a continuous-use temperature of 230C, yet Is easily melt-processlble In conventional equipment and resists chlorinated solvents.

This section was edited by Associate Editor Alan S. Brown.

Copyright American Society of Mechanical Engineers Jan 2007

(c) 2007 Mechanical Engineering. Provided by ProQuest Information and Learning. All rights Reserved.