8 December 2025
Bio-based composites can make machinery more sustainable
New research shows that bio-based reinforcements in thermoplastics can significantly improve wear resistance, friction behaviour and mechanical strength. The findings indicate that future machine components can be produced with lower environmental impact without compromising performance.
The shift toward more sustainable industrial systems is accelerating. Machines and equipment where friction and wear are critical factors face increasing demands for energy efficiency and responsible material choices. In his doctoral thesis, Lucas Kneissl investigates how bio-based reinforcements can enhance the performance of widely used engineering thermoplastics.
The work focuses on two polymers commonly used in tribological applications, POM and PA11. Both materials offer strong mechanical properties and chemical resistance and are well suited for combination with natural materials. PA11 is also fully bio-based, which makes it particularly attractive from a sustainability perspective.
"Frictional losses and wear directly affect energy efficiency, so improving these properties with more sustainable materials is an important step," says Lucas Kneissl, Doctoral Student in Machine Elements at Luleå University of Technology.
Lucas Kneissl, doctoral student in machine elements at Luleå University of Technology.
Improved wear resistance and more stable friction
By reinforcing POM with short regenerated cellulose fibres, both tensile and flexural strength increased clearly. At the same time, the wear coefficient decreased in several test cases, particularly under higher loads. The improvements are linked to changes in the tribofilm, which gained greater coverage and protected the material more effectively.
PA11 was reinforced with cellulose nanocrystals, leading to substantial improvements in compressive strength, thermal stability and crystallinity. The most notable effect was a reduction of nearly 90 percent in the wear coefficient. The friction coefficient also decreased, likely due to how the tribofilm formed on the counter surfaces.
"The bio-based reinforcements produced remarkable improvements in wear resistance," says Lucas Kneissl.
Thermal post-processing also proved important. Different annealing parameters led to further improvements and resulted in a total reduction in the wear coefficient of more than one order of magnitude compared with untreated PA11. Techniques such as Raman spectroscopy and X-ray diffraction were used to examine tribofilm structure and worn composite surfaces, providing valuable insights into the mechanisms that drive friction and wear.
"These results show that bio-based composites can be strong, reliable and suitable for real engineering applications," says Lucas Kneissl.
Contact
Lucas Kneissl
- Research Assistant
- 0920-493320
- lucas.kneissl@ltu.se
- Lucas Kneissl
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