| Short bamboo fibers were selected as reinforcement materials in polypropylene (PP) matrix for the following reasons. Firstly, bamboo has the fastest growth rate among the various types of renewable natural fibers. Second, the cellulose fibers in bamboo are aligned along the length of bamboo providing maximum tensile strength, flexural strength, and rigidity in that direction. Attributes like60%cellulose, considerably high percentage (32%) of lignin and2-10°microfibril angle are responsible for making bamboo a preferred reinforcing agent. However, the poor interfacial compatibility between the polar bamboo fiber and the non-polar plastics matrix influences the mechanical performance of composites, limiting application and promotion of bamboo-plastic composites (BPC). Therefore, how to improve the interfacial compatibility between bamboo fiber and plastics and enhance the mechanical performance of BPC is an important subject in the study field.Due to low strength and toughness of the bamboo fiber/polypropylene (BF/PP) and poor compatibility between the bamboo fiber and polypropylene resin, pretreatment (Alkali treatment of the bamboo fiber with10wt%NaOH solution, and the surface coupling process of nano-SiO2with KH-570) of the fillers was carried out before the experiment. The results showed that BF provided a larger surface area for leaching out the cementing materials during alkali treatment, which could improve the mechanical interlocking between bamboo fiber and the PP matrix. Surface coupling treated nano-SiO2could improve the compatibility of filler and PP matrix.Bamboo fiber/polypropylene (BF/PP) and poly(ethylene-octene) copolymer-grafted-maleic anhydride (POE-g-MAH)/bamboo fiber/polypropylene (POE-g-MAH/BF/PP) compo-sites were prepared through blending PP, BF and POE-g-MAH by a twin screw extruder and injection molding machine, and the morphologies, crystalline structures, melt flow index and mechanical properties of composites were analyzed by SEM, XRD, DSC, MFI and mechanical testing. The results demonstrated that the presence of POE-g-MAH in the PP/BF composites with30%of BF mass fraction results in more crystal imperfection of the PP component, the significant improvement of impact strength for PP/BF composites, and the improvement of uniform dispersion of BF in the PP matrix. The addition of2.5%of POE-g-MAH mass fraction can improve both strength and toughness of BF/PP composite, and the impact strength of POE-g-MAH/BF/PP (7.5/30/62.5) composites are better than that of pure polypropylene. The improvement of impact strength of the composites mainly results from energy-absorption process, better stress transfer and the increase in interfacial adhesion between PP and BF in the presence of POE-g-MAH. In order to maintain the composites with enough strength and stiffness while toughen PP/BF composites, different mass percents of nano-SiO2were added to BF/PP (30/70) and POE-g-MAH/BF/PP composite materials. The morphologies, crystalline structures, thermal stability, water absorbency and mechanical properties of composites were analyzed by SEM, TG, DSC, VST and mechanical testing. The results showed that incorporation of nano-SiO2and POE-g-MAH could improve the dispersion of bamboo fiber in the polypropylene matrix and enhance the interfacial interaction between the fiber and the matrix, resulting improving thermal stability and the water absorption of the composite materials. Experiments demonstrated that nano-SiO2tended to increase the strength and stiffness of the composite materials while POE-g-MAH mainly improved the toughness of the composites. The analysis of DSC and XRD indicated that the presence of BF result in more crystal imperfection of the PP component.2.5wt%and5wt%nano-SiO2had the heterogeneous nucleation effect on PP, however, the effect reduced with incorporation of7.5wt%and10wt%nano-SiO2in the composites. The addition of POE-g-MAH resulted in the decrease in the melting point and the crystallization temperature of PP in the composite materials. |
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