Interfacial morphology between ramie fibers and phenolic resins : effects of plasma treatment and cure cycle

Natural fiber–reinforced polymer composites offer many advantages over conventional composite materials, such as availability, low cost, inexpensive, lightweight, and high specific mechanical properties. However, the applications of these materials are still limited due to the challenges in achieving a good interface between the fibers and matrix. This is highly influenced by the fiber surface characteristics and the polymer matrix properties. Therefore, in this study, the surface characteristics of ramie fibers were modified using low-pressure plasma treatment in order to improve their interface to the phenolic resin. Furthermore, the effects of using two different curing cycles (acid cure and thermal cure) on the properties of short ramie fiber-phenolic composites were also investigated. A new method for making mats of random short ramie fibers was developed and used for the fabrication of composites containing plasma-treated fibers. The flexural properties of all composites were tested and the obtained fracture surfaces were investigated using LV-SEM. The results indicate that both plasma treatment and cure cycle conditions influence the fiber–matrix interface and consequently the flexural properties of the composites.