The low-hanging fruit in replacing metals with plastics has long been picked. Now it?s time for polymers to do some heavy lifting, literally. DuPont Engineering Polymers is betting on its new portfolio of ?superstructural? thermoplastics to enable the advent of the next era in metal replacement.

Developed to approach the property levels of metals, individual grades in the DuPont superstructural portfolio combine an engineering plastic with up to 60% content of either short- or long-fiber reinforcement. Base polymers include Zytel HTN (high-temperature PA), Zytel PA 66, and Rynite PET thermoplastic polyester.

According to Dupont, the current superstructural portfolio includes 12 grades. There are four resins reinforced with long glass fibers, including a Zytel HTN grade containing 50% long glass and three Zytel PA 66 resins with long-glass loadings of 40% to 60%. Eight superstructural grades use short glass fibers, with six of them based on Zytel HTN with glass, and in one case mineral, reinforcement at loadings up to 50%. Of the remaining two grades, one is a Zytel PA 66 resin with 60% glass, and the other is a Rynite PET grade with 55% glass.

?These resins provide levels of stiffness and strength much closer to metal than conventional engineering plastics, and certain grades deliver much higher impact resistance than conventional engineering plastics without sacrificing mechanical strength and stiffness,? says Cynthia Crouch, global marketing manager for mechanical solutions.

Crouch also notes that the aim of the new offerings is to give engineers the tools they need to reduce weight and system costs and improve the reliability and performance of structural components now made of metals. Early commercial automotive applications include sunroof frames, air suspension system parts (such as the module for the 2006 Range Rover that uses superstructural Zytel HTN to withstand high burst pressure and compressive forces), an armrest retractor spline, and steering column supports and housing components. Additional potential uses include supports and housings for mirrors, interior consoles and transmissions, door handles, and door modules.

Nonautomotive applications are also ramping up, according to Crouch. Structural frames for mobile phones molded from a superstructural Zytel HTN resin are said to meet requirements for strength, impact resistance, and dimensional stability. Other applications are reportedly opening up in sporting goods, recreational vehicles, furniture, appliances, and industrial equipment.?MM

DuPont Engineering Polymers
Wilmington, DE
(800) 441-0575
http://plastics.dupont.com

June 2005