Polymer nanocellular fibers via supercritical carbon dioxide based extrusion foaming

The quest of novel materials for making lighter fibers for textile and non-woven fabrics applications prompts us to exploit the nanocellular fibers. Thermoplastic polyurethane nanocellular fibers were prepared by extrusion foaming using supercritical carbon dioxide as the blowing agent. Nanoparticles such as nanoclay, multi-walled carbon nanotube, and graphene nanosheets were added as the heterogeneous nucleation agents in order to achieve high-efficiency nucleating effects. Surface functionalizations on nanoparticles were conducted in order to ensure the high-degree dispersion of nanoparticle in the polymer. Optimization of processing conditions is necessary for achieving uniform foams with cell size below 1 μm in the fiber having a diameter of less than 30 μm. The density of nanocellular fiber was reduced by 30-50% as compared with that of bulk polymer.