Effect of fiber orientation on friction behavior of rape stalk /PVC composites in water environment

Abstract

The rape stalk/ polyvinyl chloride (PVC) composites were prepared by hot pressing after the rape stalk treated by alkali–ultrasound synergistically. Abrasive wear and sliding friction wear tests were performed to examine the influence of fiber orientation on the friction and wear characteristics of the composites. Furthermore, the wear mechanism was thoroughly discussed based on the analysis of the alterations in the mechanical properties of the composites. The results indicated that alkali–ultrasound treatment improved the wettability of the rape stalk and the adhesion between the fiber and matrix, effectively boosting the mechanical properties of the composites. Compared to with 90° fiber orientation, the 0°-oriented composites exhibited significantly higher mechanical properties, with tensile, flexural, and impact strengths of increased by 33.94 MPa, 55.16 MPa, and 7.98 kJ/cm², respectively. Microcutting and fiber debonding were identified as dominant mechanisms under abrasive wear. For sliding wear, two distinct stages were observed, and with friction force showing a positive correlation to load and speed, inversely proportional to friction coefficient. In addition, under both forms of friction and wear, the mass loss and specific wear rate of composites increased with fiber orientation, exhibiting significantly higher values in wet conditions compared to dry conditions. This study provided technical support and a theoretical basis for structural design optimization and expanded the application potential of the rape stalk/PVC composites.