Plastics breakthrough could improve your car's mileage

A new chemical process could give plastics wider manufacturing applications.

A new thermal engineering process could make it viable to use lighter plastic product components in things such as vehicles, LEDs and computers. Until now, the material has been overlooked for certain applications because of its limitations in dissipating heat, but scientists from the University of Michigan have found a way to change plastic's molecular structure, making it as thermally conductive as glass. This advanced plastic could make products lighter, cheaper and more energy-efficient, and would be particularly useful in electric vehicle manufacturing since weight has a direct bearing on range.

A sample of heat - conducting polymer is tested for thickness in U-M's Lurie Nanofabrication Facility.

Previous attempts to improve plastic's conductive properties have seen it packed with metallic or ceramic fillers, which has been largely unsuccessful, not to mention expensive. This new approach uses a chemical process to expand and straighten plastic's tightly coiled molecular chains, giving heat energy a more direct route through the material. The plastic polymer is dissolved in water, then electrolytes are added to raise its pH. The individual links in the polymer chain take on a negative charge, causing them to repel each other, spread apart and uncoil. The solution is then reformed into a solid plastic film using an industrial process called spin casting.

"Researchers have long studied ways to modify the molecular structure of polymers to engineer their mechanical, optical or electronic properties, but very few studies have examined molecular design approaches to engineer their thermal properties," said associate professor of mechanical engineering Kevin Pipe. "While heat flow in materials is often a complex process, even small improvements in the thermal conductivities of polymers can have a large technological impact."