Future development direction! Major advances have been made in the field of heat-conducting plastics

If advanced plastics can better solve the heat dissipation problem, then they can bring lighter, cheaper, and more energy-efficient product components including those used in automobiles, LEDs, and computers.

A new technology that can change the molecular structure of plastics is moving in this direction.

A new study developed by the Materials Science and Mechanical Engineering Research Group at the University of Michigan and published in "Science Progress" shows that the process is inexpensive and highly scalable.

This idea may also be applicable to various other plastics. After preliminary testing, it makes a polymer as a thermally conductive glass, although it is far inferior to the performance of metals or ceramics, but its heat dissipation is six times better than the same untreated polymer.

"In many applications, plastics are gradually replacing metals and ceramics. But they are poor thermal conductors, and no one even thinks they can be used in places where effective heat dissipation is required." Said Jinsang King , a professor of materials science and engineering at the University of Michigan , " Try a method that has not been used before and change it by applying thermal engineering plastics. "

This method is completely different from the previous method of adding metal and ceramic reinforcement materials to plastics. The traditional method can only carry out limited development. It must be filled with a large amount of expensive reinforcement materials, and the properties of plastics should be changed by inappropriate methods. However, new technologies are developed by changing the structure of the material itself.

Plastic consists of tightly wound long-chain molecules, like a bowl of pasta entwined together. When the material gets hot, the conduction of heat must travel between these chains. Because the roundabout journey hinders the progress of conduction, the heat transfer becomes much more troublesome.

The team, which includes Kevin Pipe, associate professor in the Department of Mechanical Engineering at the University of Michigan, Chen Li, a graduate student in mechanical engineering, and Apoorv Shanker, a graduate student in materials science and engineering , used a chemical method to expand and straighten the molecular chain. This approach gives thermal energy a more direct path through the material. After completing this project, they began to study typical polymers or plastics. They first dissolved the polymer in water, and then added electrolyte to the solution to increase its pH and make it alkaline.

The individual chains in the polymer chain are called monomers, and they are mutually repelling due to their negative charge. When the monomers are separated, they unwind the chain tightly. Finally, the water and polymer solution are sprayed on the board using a method known as spin casting in a common industrial synthesis process to dehydrate it into a solid plastic film.

The molecular chains that are not entangled in the plastic make heat penetration easier. The research team also discovered the second advantage of this method-strong polymer chains can help them stick together more closely, making them more thermally conductive.

"Polymer molecules transfer heat by vibration, and a strong molecular chain makes it easier to vibrate." Shanker said. "Imagine a tight guitar string compared to a loosely wound rope. When we pull the string, the guitar string will vibrate, but the rope will not. The same is true for polymer molecular chains."

Pipe says this work is very important because temperature is important in a large number of polymer applications.

"For a long time, researchers have been studying ways to change the molecular structure of polymers to make polymers have mechanical, optical or electronic properties, but few teams have studied the molecular structure to change their thermal properties." Pipe said. "The heat flow in the material is often a complicated process, and even a small change in the thermal conductivity of the polymer will have a great technical impact."

The team is now trying to combine the new technology with several other heat dissipation methods to improve the thermal conductivity of the composite. They are also committed to applying this concept to other types of polymers beyond this research. It may take several years to make it a commercial product.

"We are studying the use of organic solvents to apply this technology to water-insoluble polymers."

Chen Li said. "But we believe that the concept of using electrolytes to heat polymers is a multi-purpose concept that will be applied to many other materials."

Article link: China Plastic Online http://info.21cp.com/industry/Qianyan/201708/1314134.htm