Influence of types of alkali treatment on the mechanical properties of hemp fiber reinforced polyamide 1010 composites

In order to develop the new engineering materials such as structural materials and tribomaterials based on all plants-derived materials, the purpose of this study is to investigate the influence of types of alkali treatment on the mechanical and tribological properties of hemp fiber (HF) reinforced plants-derived polyamide 1010 (HF/PA1010) biomass composites. HF were surface-treated by four types of surface treatments: (a) alkali treatment by sodium hydroxide (NaOH) solution, (b) alkali treatment by sodium chlorite (NaClO2) solution, (c) alkali treatment by NaOH solution and surface treatment by ureido silane coupling agent, and (d) alkali treatment by NaClO2 solution and surface treatment by ureido silane. The volume fraction of hemp fiber in the composites was fixed with 20vol.%. HF/PA1010 composites were extruded by a twin screw extruder and injection-molded. Mechanical properties such as tensile, bending and tribological properties by ring-on-plate type sliding wear testing were evaluated. It was found that the effect of the types of alkali treatment on the mechanical and tribological properties of the composites differed for each property. The mechanical and tribological properties are improved with both alkali treatments by NaOH and NaClO2 with or without the surface treatment by ureido silane coupling agent (A-1160). This may be attributed to the interfacial interaction and interphase adhesion between HF and PA1010 according to the type of these alkali treatments. The combination NaClO2 and A-1160 is the most effect improvement for the mechanical and tribological properties of HF/PA1010 biomass composites. It follows from these results that it may be possible to develop the new engineering materials with sufficient balance between mechanical and tribological properties. © 2016 Author(s)