Don’t Rub, You’ll Burn

The plastics industry continues to produce innovations that will help us in every aspect of our lives and make our lives easier. Sometimes a folding picnic chair, sometimes an insulin injector is actually a situation analysis that we are not aware of and do not appreciate without experiencing its deficiency.

An astonishing 23% of global energy consumption can be attributed to friction losses. Therefore, components with reduced friction make an important contribution to conserving resources and achieving climate protection targets. In the case of plastics, reduced friction can also reduce the presence of microplastics in the environment. With the development of microcapsules filled with liquid lubricants for plastics, the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam and the Plastics Center SKZ in Würzburg support these goals. Self-lubricating plastics are intended to provide up to 85% less wear. A variety of applications expose materials to friction, whether sliding doors, plastic gears or other moving components. Plastic manufacturers sometimes incorporate solid lubricants into plastics to reduce component wear. However, relatively few solid lubricants are suitable for plastics processing. In a joint effort, the two research institutes have succeeded in encapsulating liquid lubricants in such a way that they can be incorporated into polymers as functional agents and then develop all the advantages of a liquid lubricant in the component.

High temperature mixing without damaging the capsules was a challenge. "We were able to incorporate the liquid lubricant-filled microcapsules of Fraunhofer IAP into thermoplastics using a twin screw extruder," says Moritz Grünewald, a researcher at the SKZ Plastics Center Materials Development Group. High temperatures without damaging the capsules are an excellent statistic. Only when friction occurs on the final component should the capsules break and release the lubricant. This allows the component to lubricate itself automatically. Friction and wear tests showed a wear reduction of up to 85% on the plastic. Therefore, the components last significantly longer and produce less microplastics,” said Grünewald. Based on these results, the material system is further optimized for potential applications. Development is now focusing on the improved mechanical and thermal properties of self-lubricating plastics. Testing of reinforcement materials The additional use of reinforcing materials such as fibers is intended to make self-lubricating plastics more mechanically stable.In the project, the researchers investigated which fiber type is best suited for this purpose and how the microcapsules can best be attached to the plastic matrix. It can also be incorporated into high melt plastics to further expand the possibilities.

Numerous studies from industry highlight the need for new plastics with optimized friction and wear properties. Micro-encapsulation technology has great advantages for companies in this regard. A wide variety of fluid and advanced lubricants are now available as internal lubricants with optional release properties. The project is accompanied by a committee that includes companies from all sectors of the plastics industry, lubricant manufacturers and micro-encapsulators.