蛭石填充尼龙66复合材料的结构与性能研究

Structure and properties of PA66 filled with vermiculite powder

通过熔融共混法制备了一系列蛭石填充尼龙66复合材料,测试了复合材料的力学性能,用SEM、DSC、WAXD和HAAKE-Ⅱ高压毛细管流变仪等方法研究了复合材料的微观结构、非等温结晶过程和结构、流变性能。结果表明:蛭石的加入提高了尼龙66的拉伸性能和弯曲性能。随蛭石填充量的增加,尼龙66复合材料的拉伸强度变化不大,均提高了约12%;弹性模量、弯曲强度和弯曲模量基本呈线性上升趋势,当填充量为26%时,分别提高了116%、32%、55%;当填充量小于16%时,冲击强度降低不多,但填充量大于16%时,冲击强度降低较多;蛭石对尼龙66具有有效的异相成核的作用。与纯尼龙66相比,蛭石填充复合材料的结晶温度升高,过冷度降低,结晶峰半高宽减小,半结晶周期减小;蛭石在尼龙66基体中分散较均匀,部分蛭石粒径在纳米级,蛭石与尼龙66树脂之间有较好的粘结作用;蛭石的加入使尼龙66非牛顿指数减小,尼龙66对剪切力敏感性下降。

PA66/vermiculite powder （VMT） composites were prepared by melt blending, and their mechanical properties were determined. The microstructure, crystallization behaviors and crystal structure in cooling process and rheological behaviors were studied by means of SEM, DSC, WAXD and HAAKE-Ⅱ rheometer. When the VMT content was about 26 % （wt）, the tensile strength, tensile modulus, flexural strength and flexural modulus of composite were raised respectively by 12%, 116%, 32% and 55%. The Izod impact strength was basically maintained when the VMT content was not greater than 16 % （wt）, and was decreased when the VMT content was greater than 16% （wt）. Results of DSC showed that the existence of VMT could raise the crystallization temperature, reduced the super-cooling degree, and narrowed the range of crystallization temperature of PA66, so VMT sped up the crystallization process of PA66, and had effect of heterogeneous nucleation to PA66. Most of VMT dispersed evenly in the PA66 matrix. PA66 and its composites were pseudoplastic fluids. The non-Newtonian indexes decreased with the addition of VMT, and so the influence of shearing force on apparent viscosity of the composite was weaker than that of pure PA66.