Preparation And Properties Of Different Fillers/wheat Straw Fiber/polyethylene Composite Materials

In this paper,wheat straw fiber(WSF)and high-density polyethylene(HDPE)in guanzhong area of shaanxi province were used as raw materials.Three different types of fillers,namely dolomite,talc and wollastonite,were used as filling additives.The effects of different filler contents and modified WSF with-aminopropyl triethoxy silane(KH550),maleic anhydride(MA)and double(triethoxy silico-propyl)tetrasulphide(Si69)on the mechanical properties,water absorption properties,thermal stability and crystallization properties of WSF/HDPE composites were studied.Fourier infrared spectrometer(FTIR)was used to analyze the chemical structure of WSF before and after modification.Scanning electron microscope(SEM)was used to analyze the morphology changes of the tensile fracture surface of WSF/HDPE composite material before and after filling.The main conclusions are as follows:(1)With the increase of WSF content,the mechanical properties of WSF/HDPE composites showed a trend of first increasing and then decreasing,and the water absorption increases.When WSF content was 40wt%,the mechanical properties of WSF/HDPE composites were the best.The addition of WSF promoted the crystallization of HDPE,improved the crystallinity,and reduced the interface properties of the composites.(2)With the increase of filler content,the powder aggregation phenomenon will occur when WSF/HDPE composites are filled with different types of fillers,and the water absorption performance of the composites will be enhanced.The mechanical properties of the composites were optimized when the filler content was 5wt%.In terms of tensile properties,wollastonite>dolomite>talc powder.In terms of bending performance,wollastonite>dolomite>talc powder;In water absorption,wollastonite>talc>dolomite.The SEM experiment results showed that the interface bonding effect of the composites was good after filling with appropriate amount of fillers and the pores between WSF and HDPE were filled with fine particles.(3)Dolomite partially replaces WSF filled HDPE composites.When the dolomite content is 4wt%,the mechanical properties of the dolomite/WSF/HDPE composites prepared reach the best.The replacement of WSF with dolomite has little effect on the thermal stability and crystallinity of WSF/HDPE composites.The water absorption rate of composites decreases gradually with the increase of dolomite content.SEM analysis showed that the interface bonding effect of the composite was good after dolomite was substituted for WSF.(4)WSF modified by KH550,MA and Si69 can reduce the hydroxyl group on the fiber surface,improve the water resistance of dolomite/WSF/HDPE composites,and improve the crystallinity of composites.The mechanical properties of dolomite/W SF/HDPE composites were improved the most by MA modified fibers.However,although KH550 and Si69 treatments reduced the hydroxyl groups on the surface of the fiber,their effects on the mechanical properties were not obvious.WSF/HDPE composites were prepared with MA modified talc powder and wollastonite respectively.The mechanical properties of composites were significantly higher than that of unmodified materials,and the water absorption of composites was significantly reduced.The SEM test results show that the interface of the composites treated with three modifiers is improved,and the MA effect is better.