Oxygen plasma treatment of bamboo fibers (BF) and its effects on the static and dynamic mechanical properties of BF-unsaturated polyester composites

A novel method for the preparation of bamboo fibers (BF) has been investigated that includes crushing, rolling, and other combing techniques with 1,4-butanediol as a dispersant. The fibers were treated by oxygen plasma to improve their interfacial adhesion to unsaturated polyester (UPE) resins. Composites were prepared from the plasma treated fibers (BFtr) and UPE by hand lay-up compression molding. BFtr significantly increased the tensile strength, flexural strength, and flexural modulus of the resulting BF-UPE composites. Dynamic mechanical analysis indicated that the plasma treatment essentially increased the storage modulus and glass transition temperature of the composites. The damping parameter of the composites showed a decreasing trend in the glassy region, while the opposite was true for the rubbery region. X-ray diffraction analysis indicated that the treatment did not change the crystal structures within the fibers but increased slightly their crystallinity indices. X-ray photoelectron spectroscopy analysis revealed that the surface of BFtr had a higher oxygen concentration and oxygen/carbon ratio than that of BF. The scanning electron microscopy graphs of the tensile-fractured surface of the composites demonstrated an improved interfacial adhesion between BFtr and UPE resins.