Study Of Three-dimensional Orthogonal Ramie Fabric Reinforced Polylactic Acid Composites On Its Preparation And Properties

Green textile composites have won widespread applications in advanced technology fields such as aerospace and automotive due to their superior mechanical properties,low density,and degradability.Nowadays,ramie fibers reinforced polylactic acid composites are often prepared by melting method.However,ramie fibers are easy to be damaged during the mixing process with matrix,which reduce the mechanical properties of materials and limit the application of ramie/polylactic acid composites.In this thesis,two-dimensional braiding technology and three-dimensional weaving technology are used to prepare ramie fabric reinforced polylactic acid composites with high mechanical properties.The effects of the twist ratio of ply/single yarn,the curing process,ramie content,and porosity on the mechanical properties of three-dimensional orthogonal ramie/polylactic acid composites are studied,and the influence of different fiber content on the sound absorption performance of the composites has been analyzed.It is expected that this excellent performance,low-cost composite has good application potential in the field of automobile manufacturing.Experimental results show that:(1)The twist ratio has a positive effect on the mechanical properties of ramie ply yarn composites.When the twist ratio is 0.3,the ramie ply yarn composites can obtain the best tensile properties.(2)The optimal curing process of three-dimensional orthogonal ramie/polylactic acid composites are 190 ℃,5 MPa,30 min.When the ramie content is 50%,the flexural and shearing properties of the composites are higher than those of composites with fiber content of 30%,40% and 60%,and the flexural performance is better than other reported ramie short fiber composites and two-dimensional ramie fabric composites.(3)The loading direction has a significant impact on the compression performance of the composites,and the Z-direction compression performance is better than the weft compression performance and the warp compression performance.Moreover,composites with 50% ramie content have the best compression performance in different loading directions,which is closely related to the interfacial bonding ability of fiber and resin,the weft density of the reinforcement and the ramie content.(4)The sound absorption performance of the three-dimensional orthogonal ramie/polylactic acid composites is related to fiber content.The sound absorption coefficient of composites with the ramie content of 60% is 0.8 at 6400 Hz,which is much higher than the other three composites of 0.2,0.3 and 0.4,indicating that these materials can be used as a sound absorbing material in the automobile manufacturing industry.Three-dimensional orthogonal ramie/polylactic acid composites with excellent performance were prepared by advanced textile methods in this thesis,which can meet the needs of automobile manufacturing and transport fields,and reduce environmental pollution and the waste of resources.