Preparation And Properties Of Calcium Sulfate Whisker Reinforced HDPE/PA6 Composites

High-density polyethylene(HDPE)is widely used in industrial and agricultural production because of its excellent physicochemical properties.However,its application is limited by its relatively low strength and low temperature resistance.Since PA6 characterizes high strength and is low temperature resistance,blending HDPE with PA6 is an ideal route to obtain new material with multiple properties.Nevertheless,the blend of HDPE and PA6 displays two-phase morphology and inferior mechanical property,because the difference between the chain structure of HDPE and PA6 is so large that they are immiscible of each other.Due to its high modulus,strength and aspect ratio,calcium sulfate whisker(CSW)are used not only to strengthen the material but also significantly toughen the material by inhibiting the initiation and propagation of cracks.So,in this thesis,we firstly functionalized calcium sulfate whisker and then controled the localization and dispersion of these calcium sulfate whisker to obtain composites with excellent toughness and strength.Furthermore,the effects of CSW contents on the microscopic morphology and macroscopic properties are also analyzed.The main achievements are as follows:In this paper,using the method of wet modification,the stearic acid(SA)was used as modifier of two-phase HDPE/CSW composite and glycidyl methacrylate(GMA)was used as modifier of three-phase HDPE/PA6/CSW composite.The results of FT-IR and thermogravimetric analysis(TGA)prove that the Modifier SA and GMA successfully link to the CSW surface.By comparing the contact Angle and activation index of CSW with different SA content,the optimal dosage of SA was 6%.The microstructure of HDPE/CSW composites and HDPE/PA6/CSW composites were observed by SEM,and the results showed that the CSW in the HDPE/CSW composites were dispersed uniformly in HDPE without agglomeration,and the two-phase interface was blurred after SA modification.The compatibility of CSW and HDPE were improved.In the HDPE/PA6/G-CSW composite,the CSW is fixed in the PA6 phase,no longer enriched with the interface of HDPE and PA6,and the two ends of the whisker are inserted into the HDPE to enhance the performance of the HDPE/PA6/CSW.The comparison of mechanical properties between modified and unchanged composites showed that the tensile strength and flexural strength of the two-phase composites were obviously improved by the addition of SA-CSW,and the tensile and impact properties of the HDPE/PA6/CSW were significantly enhanced by the GMA modification CSW.The DMA test shows that the addition of CSW can improve the energy storage modulus of HDPE/CSW composites and HDPE/PA6/CSW composites.After the modification of CSW,the effect of modified CSW on the energy storage modulus of composites is more significant.