| An ultrasonic wave reactor was designed for studying the ultrasonic degradation of PA6. The factors (initial molecular weight, irradiation time, ultrasonic intensity as well as ultrasonic action distance) affecting the ultrasonic degradation of PA6 melt were investigated.Ultrasonic degradation kinetics of HPA6 melt fits the equation: Mt =M@ +Ae-kt. The degradation mechanism obeys free-radical-rupture mechanism.The experimental results show that die pressure of PA6 and PA6/HDPE blends is reduced remarkably in the presence of ultrasonic wave during extrusion, but the melt temperature and mass flow rate of PA6/HDPE get increased. So, ultrasonic irradiation is in favor of processing of PA6/HDPE blends.The effect of ultrasonic irradiation on structure and mechanical, crystallizing, rheological properties of PA6/HDPE blends was also studied through SEM, DSC, X-ray, mechanical test and so on. The experimental data show that the structure and properties of PA6/HDPE blends have changed under the action of ultrasonic wave. Under a certain ultrasonic intensity, themechanical properties have been improved, but when we strengthen the intensity, the mechanical properties decrease. Ultrasonic irradiation could also enhance interfacial interactions and improve the dispersion and distribution of HDPE in the matrix. The average particle diameter is decreased markedly, it changes from 17.35 um to 13.65 urn in the presence of 50W ultrasonic irradiation.After being treated by ultrasound, the dynamic cross-point modulus (Gx) of HPA6/HDPE blends is increased while zero-shear viscosity (η0) of HPA6/HDPE blends is decreased; the slope of logG'/logG" of HPA6/HDPE blends in the endmost area is increased, all the discussion shows that the compatibility of HPA6/HDPE is improved under the irradiation of ultrasound.The crystallining properties of HDPE in PA6/HDPE (80/20) blends are also influenced by ultrasonic irradiation.
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