Preparation of Micro and Nanocellular TPU-Graphene Nanocomposite Foam by Supercritical CO2 Foaming

摘要

Thermoplastic polyurethane (TPU) possesses many special characteristics. The flexibility, rigidity, and elasticity can be adjusted by controlling the ratio of soft and hard segments. Additionally, the chemical properties of TPU can be varied by using different starting monomers. Due to its versatile physical and chemical properties, TPU is commonly used in transportation, construction, and biomaterials. The technique of foaming TPU by CO2 is still under investigation. To avoid the effect of additives that are found in commercially available polymer, we synthesized TPU ourselves using a pre-polymer method. In addition, graphene was added as the nucleation agent. The synthesized TPU was foamed by batch foaming using super critical CO2 as the blowing agent, and the effect of saturation temperature on the cell morphology of TPU foam was examined. The average cell size of TPU foam decreased from 1.8 μm to 800 nm, after only 0.1 wt% of graphene being added. Keywords: thermoplastic polyurethane, CO2, graphene, microcellular foam, nanocellular foam