Performance Improvement of Epoxy Polymer Monolith Films by Reinforcing with Cellulose Fibers

Abstract

In this article, we demonstrate the preparation of epoxy polymer monolith composite films with cellulose fibers for improving the mechanical property, where the monolith is a porous material with a co-continuous skeletal structure. The preparation includes lamination process or simple hanging process for cellulose-fiber nonwoven sheet impregnated with monolith precursor mixtures, followed by polymerization induced phase separation based on spinodal decomposition. The resulting monolith composite films were surface skin-less, exhibiting the pore sizes from 200 nm to 1.5 μm. The tensile Young’s modulus and strength were higher than those of the neat monolith film and the previously-reported cellulose nanofiber-reinforced monolith films. The ionic conductivity of the composite films with lithium-ion electrolyte was comparable to that of commercially-available polyolefin porous membranes. The epoxy polymer monolith composite film is expected to have a great potential as a promising separator for next-generation lithium ion batteries by taking advantage of its high heat resistance and winding channel structure.