Enhanced mechanical properties and water resistance of bamboo fiber–unsaturated polyester composites coupled by isocyanatoethyl methacrylate

Bamboo fibers were mechanically extracted from raw green bamboos by crushing, rolling, and combing techniques with 1,4-butanediol as a solvent. The morphology of the bamboo fibers thus obtained was analyzed. The bamboo fibers were treated with isocyanatoethyl methacrylate (IEM) in the presence of dibutyltin dilaurate as a catalyst, to improve the interfacial adhesion between the fibers and unsaturated polyester (UPE) resins. The bamboo fibers reinforced UPE composites were prepared by hand lay-up compression molding. FTIR, XPS, and NMR analyses indicated that the IEM was covalently bonded onto the bamboo fibers via carbamate linkages. The IEM treatments significantly increased the tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites and yet decreased the impact strength of the composites. The SEM images of the tensile-fractured surfaces of the IEM-treated bamboo fibers–UPE composites revealed that the fiber treatments markedly improved the interfacial adhesion between the bamboo fibers and UPE resins.