Jute yarn-wound composites: optimization of methods for evaluating mechanical properties and improvement of mechanical properties

Abstract

Filament winding (FW) technology is an important molding technology to obtain high-performance filament-wound composites. However, current methods for evaluating the mechanical properties of plant fibers for FW are directly borrowed from those of synthetic fibers, which may not be appropriate due to the heterogeneity of plant fibers and the unique twisting structure of plant fiber yarns. Herein, jute yarn Naval Ordnance Laboratory (JY-NOL) composites were prepared by FW technology using jute yarns (JYs) and epoxy resin (EP) to propose suitable methods for evaluating mechanical properties. Moreover, the improvement mechanism of mechanical properties of JY-NOL composites was elucidated by exploring the effects of the impregnation method, resin mass fraction and winding tension on the mechanical properties of JY-NOL composites. The results showed that the methods for evaluating the mechanical properties of JY-NOL composites with different JY specifications based on a five-layer winding structure were more scientific and reliable than the methods for evaluating the mechanical properties based on a 3-mm thickness. With the increase in the metric count and the decrease in the number of yarn strands of JYs, the glue loading of JYs gradually increased, and JYs had a unique twisting structure, making it difficult for the interiors of JYs to be impregnated with EP. Therefore, the winding parameters related to the impregnation method, resin mass fraction and winding tension were optimized, aiming at improving the impregnation effect of EP on JYs and reducing the voids in JY-NOL composites, thus strengthening the mechanical properties of JY-NOL composites.