Strategies for improving the strength, toughness, and winding properties of sisal fiber/polyethylene pre-preg tape

Natural fibers are renewable and environmentally friendly materials that deliver impressive performance, and can be used to reinforce pre-preg tapes for filament winding. In this study, we design a matrix structure (the LLDPE with a low melting point was arranged in the shell, while the matrix of the core layer was a mixture of the LLDPE and HDPE) to prepare a continuous sisal fiber/polyethylene pre-preg tape by considering its toughness and winding properties. We significantly improved the strength and fracture toughness of the pre-preg by “customizing” the flexible interface between the sisal fiber and the polyethylene matrix. The results of experiments showed that under the optimal dosage of 50 wt% sisal fiber, the capability of the pre-preg tape to withstand the winding-induced tension when the ratio of the LLDPE/HDPE matrix was 1:4 (50SF/40HDPE/10LLDPE) increased by 126.05 % compared with that of the 50SF/50HDPE pre-preg, due to the difference in the melting temperature between the shell and the core matrix. The elongation at break and impact strength of the pre-preg tape increased by 88.90 % and 31.72 %, respectively. The tensile strength and fracture toughness of the FMm-50SF/40HDPE/10LLDPE pre-preg tape increased by 79.40 % and 284.85 %, respectively, due to the presence of the phase with a flexible interface, and it exhibited satisfactory interlayer fusion. Its average annular tensile strength, short-term hydrostatic strength and ring stiffness were 101.52 MPa, 11.88 MPa, and 34.96 kN/m 2 , respectively. The work here widens the scope of application of sisal fiber/polyethylene pre-preg tapes in filament winding.