New technique to make heat pass through plastic -
New technique to make heat pass through plastic
Posted 12 Aug 2017 10:45 AM

Researchers in materials science and mechanical engineering at the University of Michigan (UM) have developed a new technique that can change plastic’s molecular structure to help it cast off heat. The new technique uses a process that engineers the structure of the material itself, considering the nature of plastics made of long chains of molecules that are tightly coiled and tangled like a bowl of spaghetti, Xinhua reported.
It used a chemical process to expand and straighten the molecule chains, giving heat energy a more direct route through the material. To accomplish this, the researchers first dissolved a typical polymer, or plastic in water, then added electrolytes to the solution to raise its pH, making it alkaline.
The individual links in the polymer chain, called monomers, take on a negative charge, which causes them to repel each other. As the monomers spread apart, they unfurl the chain’s tight coils. Finally, water and polymer solution is sprayed onto plates using a common industrial process called spin casting, which reconstitutes it into a solid plastic film.
The uncoiled molecule chains within the plastic make it easier for heat to travel through it. Researchers also found that the process has a secondary benefit: it stiffens the polymer chains and helps them pack together more tightly, making them even more thermally conductive.
“Polymer molecules conduct heat by vibrating, and a stiffer molecule chain can vibrate more easily,” said Apoorva Shanker, a materials science, and engineering graduate student. “Think of a tightly stretched guitar string compared to a loosely coiled piece of twine. The guitar string will vibrate when plucked, the twine won’t. Polymer molecule chains behave in a similar way,” Shanker added.

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