Plasma surface modification and bonding enhancement for bamboo composites

This paper presents plasma technology for the functionalization of both carbonized and non-carbonized bamboo surfaces, including bamboo skin, pulp, pith and mixed bamboo groups, for the production of advanced bamboo composites. Oxygen, nitrogen and argon are used as the plasma gas resources, and various plasma powers, gas pressures and treatment times investigated. Surface composition, morphology and wettability of plasma treated bamboos are characterized by using Fourier transform infrared spectroscopy (FTIR) and ESEM to understand the mechanisms of plasma treatment and chemical and physical changes of bamboo surface layer, and interface bond of bamboo composites. Results showed that the efficacy of plasma treatment was bamboo skin > pith > pulp and carbonized > non-carbonized, resulting in different surface characteristics and subsequent interface bonds of bamboo with the optimum plasma parameters being the processing time of 103s, the power of 141W and gas pressure of 38Pa. Oxygen plasma treatment generated an effective surface oxidization and oxygen-containing groups, resulted in significant change in (micro)structure of bamboo surface layer, and led to a significant improvement in the wetteability and interface bonding of bamboo surface and hence physical and mechanical properties of bamboo composites, e.g. MOR of 170 MPa with about 47% increase over untreated bamboo composites. Bamboo composites should be produced with efficacy period of 3 days after plasma treatment for the carbonized and 5 days for non-carbonized bamboo.