Effect of surface modification of unidirectional bamboo fiber on the properties of its reinforced unsaturated polyester resin composites

The surface of bamboo fibers was modified by using two sorts of methods including alkali treatment,alkali-silane treatment.Then unidirectional continuous bamboo fibers reinforced unsaturated polyester resin (BF/UP) composite was prepared by means of stitching-compression molding technology.The effects of different surface modification methods on the static and dynamic mechanical properties,water absorption were studied.SEM and FITR were used to describe the surface of treated fibers and the interface bonding condition in the BF/UP composite.The results show that the properties of the BF/UP composite after treating bamboo fiber using different modification methods all are improved.The performances of BF/UP composite are optimal with the treatment of 5wt% alkali-3wt% silane coupling agent.The BF/UP composite has the best comprehensive properties with the treatment of 5wt% alkali-3wt% silane coupling agent,whose tensile strength,flexural strength,flexural modulus and shear strength increase by 34.29%,15.95%,11.26% and 29.39% respectively.Compared with the untreated sample,the storage modulus of the BF/UP composite increases by 63.80%,the loss factor of BF/UP composite decreases,and the 24 h and 720 h water absorption of the BF/UP composite decrease by 55.35% and 27.32%.The results of SEM and FITR show that the impurity decrease and a layer of coupling agent film is attached on the surface of bamboo fiber,and there is a better interface adhesion occurs between the fiber and matrix after surface modification.