注塑温度对POM/TPU共混物分散相及力学性能的影响

研究了注塑温度对聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)共混物形态结构和力学性能的影响.实验结果表明,注塑温度影响POM基体相与TPU分散相的粘度比,195℃时两者粘度相当,在剪切流动过程中,TPU可在POM基体中形成条状分散相,可吸收较多的冲击能并阻止银纹的生长以及裂纹的产生,从而较大幅度提高共混物的缺口冲击强度.

EFFECT OF INJECTION TEMPERATURE ON DISPERSION PHASES AND MECHANICAL PROPERTIES OF POM/TPU BLENDS

The effects of injection temperature on the dispersion phase and mechanical properties of polyoxymethylene/thermoplastic polyurethane elaster(POM/TPU) blends were investigated.The experimental results showed that the notched impact strength of POM/TPU blends was greatly influenced by injection temperatures,and the highest value,19.1 kJ/m~2,appeared at 195℃,two times as high as the value obtained at 175℃.Because the viscosity ratio of POM to TPU changed with temperature,and reached 1 at around 195℃,and TPU formed strips-like structure in POM matrix along with the flow direction of the melt during injection,which could effectively absorb impact energy,prevent growth of crazes and formation of cracks.With increase of injection temperature,the average particle size of TPU decreased,and the particle size distribution became narrower.It is an effective way to toughen POM by adjusting the viscosity ratio of the dispersion phase and the matrix and controlling the morphology of the dispersion phase.