Effects of unidirectional continuous outer fibers content of bamboo on mechanical properties and microstructure of unsaturated polyester resin

The unidirectional outer of bamboo fibers (OBF)/unsaturated polyester resin (UP) composites were produced with unidirectional continuous OBF and UP. The effects of OBF content on longitudinal static mechanical properties and dynamic mechanical properties of OBF/UP composites were studied. SEM was used to observe tensile cross-section interface combination condition of composites. The results show that the static mechanical properties of OBF/UP composites increase with OBF content up to 50wt% and then decrease. When the OBF content is 50wt%, the properties of composites including tensile properties and flexural properties are most excellent. And the tensile strength, tensile modulus, flexural strength and flexural modulus of the composites are 285.52 MPa, 16.06 GPa, 359.80 MPa and 27.32 GPa, respectively; the storage modulus of OBF/UP composites increase at first, then decreases with the increase of OBF content. When OBF content is 50wt%, the storage modulus of OBF/UP composites yields the highest value. With the increase of OBF content, the glass transition temperature of OBF/UP composites decreases, and the width of the loss peak becomes broader. The cross-section microstructure indicates that the interface bonding strength is better for composites with 50wt% OBF content. The OBF/UP composites have excellent mechanical properties, which have the potential to replace the application of glass fibers reinforced plastic composites in the field of wind power blade materials, highway barrier materials, ship materials and so on.