Effect of processing sequence on the dynamic viscoelastic properties of ternary biomass composites (Hemp fiber/PA1010/PA11E) in the molten state

Abstract

For developing the new engineering materials such as structural materials and tribomaterials based on all plants-derived materials, we investigated the effect of processing sequence on the dynamic viscoelastic properties of the ternary biomass composites: 5mm cut hemp fiber (HF) filled polymer blend of plants-derived polyamide 1010 (PA1010) and polyamide 11 elastomer (PA11E) composites in the molten state. PA1010 and PA11E, which contain the polyether groups as soft segment, were made from plant-derived castor oil. The composition of the polymer blend of PA1010 and PA11E was fixed with 60/40 weight fraction. HF was surface-treated by two types of treatment: alkali treatment by NaOH solution and surface treatment by ureido silane coupling agent. The volume fraction of HF in the composites was fixed with 20vol.%. Five different processing sequences: (1) HF, PA1010 and PA11E were mixed simultaneously (Process A), (2) Re-mixing (second compounding) of the materials prepared by Process A (Process AR), (3) PA11E was blended with PA1010 (PA1010/PA11E blends) and then these blends were mixed with HF (Process B), (4) HF was mixed with PA1010 (HF/PA1010 composites) and then these composites were blended with PA11E (Process C), and (5) HF were mixed with PA11E (HF/PA11E composites) and then these composites were blended with PA1010 (Process D) were attempted for preparing the ternary biomass composites (HF/PA1010/PA11E) composites. These ternary biomass composites were extruded by a twin screw extruder and compression-molded. Their dynamic viscoelastic properties in the molten state were evaluated by oscillatory flow testing using a parallel plate type rheometer. It was found that those properties of the ternary biomass composites in the molten state are influenced so much by processing sequence. This is attributed to the change of internal microstructure of these composites such as the distribution and dispersion of HF.