Korean scientists have developed TPU with a bio-based content of up to 97%

Scientists at the Gyeongbuk Institute of Science and Technology in Daegu, South Korea, have found a way to make thermoplastic polyurethane (TPU) with a bio-based content of 97%. It is made using biomass monomers instead of petroleum-based materials.

This TPU is made from sebacic acid polyester polyol, 1,4-butanediol and isocyanate using a one-shot polymerization process. Sebacic acid is a fatty acid isolated from castor oil. For comparison, they tried reactions with bio-based aliphatic pentamethylene diisocyanate (PDI) and petroleum-based MDI, as well as combinations of the two.

TPU made using bio-based PDI has an average molecular weight of about 120,000 g/mol, a tensile strength of 20 MPa, and a tensile elongation of 587%. These properties are comparable to fossil-based TPUs, the research team said. Complex viscosity, tensile strength and strain all increase with increasing MDI content. They say it is possible to make TPU that is completely bio-based.

These materials have potential applications such as industrial sheets, screen protectors, bags, footwear, artificial leather and other apparel textiles. This R&D work was supported by the Korean Ministry of Trade, Industry and Energy as part of its Material Component Technology Development Project.