“Up to now, soundproofing components in rail transport have mostly been made of conventional foams or polyester fleeces. While functionally proven, these materials are neither biobased nor biodegradable,” said Robin Heinrich, research associate at the Institute for Circular Economy of Bio:Polymers at Hof University of Applied Sciences.
The team has been working with polylactic acid, a bioplastic that is produced at scale but to date has largely been used in applications where biodegradability is prioritized. Train soundproofing materials, by comparison, must withstand moisture and wide a range of temperatures.
RuhBio, therefore, has been working to increase the temperature resistance of the PLA and reliably preventing hydrolytic degradation. Their solution lies in a newly developed fiber structure: a so-called bicomponent fiber with a core-sheath structure combines the desired properties. The core consists of a partially crystalline PLA type with talc content, giving the material the necessary heat resistance and mechanical stability. The sheath is made of amorphous PLA with a wax component. This combination makes the nonwoven material resistant to moisture while enabling thermal bonding.
They also added caffeine to further inhibit hydrolytic degradation.
Following successful optimization, larger quantities of fibers were produced and processed into nonwovens by project partner ROWA. Cellofoam GmbH is now handling cutting and laminating, producing ready-to-install noise protection elements for real-world use.
Scheduled for completion by the end of the year, the RuhBio project is supported by Cellofoam GmbH, ROWA F. Rothmund GmbH & Co. KG, and the Thuringian Institute for Textile and Plastics Research.