Research On The Performance And Preparation Of Ramie Fiber Reinforced Composites

Owing to the advantages of high strength and high modulus, glass fiber reinforced resin matrix composites are getting great attention and applications, but it is difficult to deal with the wastes, which will cause serious harm to the environment. Compared with glass fiber reinforced polymer composites, natural fiber reinforced polymer composites not only have high strength and modulus, but also have low power consumption, low cost, biodegradable and pollution-free advantages to the environment. Therefore, using natural fibers instead of glass fiber to make composite materials is of great significance, but there are still many problems that need to be solved. In this thesis, some issues are studied in the improvement of the mechanical properties of natural fiber composites. Natural fiber and vinyl ester resin are as reinforcement and matrix, respectively.Nine different weaving methods and different specifications of plant fiber reinforced vinyl ester resin composite materials were made, and there static mechanical properties were tested. The results showed that, due to the different material types, woven methods and specifications of fibers, the static mechanics performance of the materials presented difference, because the material types determine the basic properties of materials, the weaving methods determine fiber sorting, the specifications determine the warp/weft distribution of fiber.To further study the interface relationships between fiber and resin matrix, this paper also studied the influences of additive on the properties of materials The results showed that, after adding fiber additives, the mechanical properties of composites were improved, the tensile strength and flexural modulus were increased by 11% and 20% respectively. The SEM pictures showed that, with the influences of additive, fiber and resin bonded better.The bearing capacity of ramie fiber reinforced composites is limited. In order to improve its bearing capacity, ramie fiber and glass fiber hybrid composite were studied. The effects of the hybrid ratio and sequences on the mechanical properties of the Glass/Ramie hybrid composites were investigated. The results showed that better tensile properties were obtained when glass fiber were used as the core layer while better flexural properties could be get when ramie fiber was employed as the core layer.Based on the overview of the ageing theories for resin-based composite materials, three different accelerated ageing, including water, salt fog and ultraviolet of the composite materials were tested in this paper. The results showed that, the damage of water is greater than salt-fog which is greater than ultraviolet. The samples under water firstly reached the maximum water uptake rate, and the samples under salt-fog had a small water uptake rate.Finally, residual strength model was used to predict the residual strength of composite materials. It showed that, after 10 years of aging, residual strength of specimens in salt fog environment retained 78%, and the residual strength of specimen in ultraviolet environment retained 81.9%.