Extrusion And Properties Of PP/EPDM Thermoplastic Elastomers Using Dynamical Vulcanization

The reactive extrusion of the polymer is a technology that combines polymersynthetization with extrusion. Its advantages include short reaction cycle, lower energyconsumption, minimized pollution, and lower cost. In this dissertation, the PP-g-MAHsamples were prepared via reactive extrusion. The effect of the dicumyl peroxide (DCP)content on the degradation of the PP was investigated. Then the80/20PP/EPDMthermoplastic elastomers were extruded using dynamical vulcanization. The effect of the DCPcontent on their rheological properties, phase morphology, and mechanical properties wasstudied. Finally, the pure PP and PP/EPDM thermoplastic elastomers were used for theextrusion foaming. The cellular structures of the foamed samples were analyzed.Rheological measurement and Fourier transform infrared spectroscopy analysis wereconducted on the prepared PP-g-MAH. The results showed that increasing the DCP contentfrom0.2to0.6phr increased the shear viscosity and reduced grafting degree, whereas afurther increase to1.0phr yielded obviously reduced shear viscosity and increased graftingdegree. Therefore, the degradation of the PP could be decreased as balancing the competitionbetween the grafting reaction and degradation reaction during the reactive extrusion viacontrolling the DCP content.Phase morphology and properties of the80/20PP/EPDM thermoplastic elastomersextruded using dynamical vulcanization were observed and measured. The results showed thatin the PP/EPDM thermoplastic elastomer prepared by adding0.02phr DCP and2phrtrimethylol propane triacrylate (TMPTA), which was denoted as T2sample, most of theunvulcanized EPDM droplets had diameters of about0.1~0.4μm. The T2sample exhibitedhigher gel content. Its melt strength was1.8cN, which was9.1and2.5times of that of the PPand T0sample, respectively. The low temperature (-20℃) impact strength of the T2samplewas40.0kJ/m2, which was30.0and6.2times of that of the PP and T0sample, respectively.The cell distribution across the fractured surface of the foamed T0sample was more uniformthan that of foamed PP sample. Compared with the foamed T0sample, the foamed T2samplepossessed smaller average cell diameter, higher cell density, higher expansion ratio, and lowerfoam density.