Ethylene Plasma Induced Polypropylene/polyethylene In Situ Polymerization Alloying At Low Temperature

A dielectric barrier discharge(DBD)device was used in this study to produce the polymer with ethylene(C2H4)as the monomer and argon(Ar)as the inorganic medium at atmospheric pressure,and the polymer obtained was a light yellow solid with a certain degree of crosslinking.Further,we studied the surface modification of polypropylene(PP)by C2H4/Ar plasma,prepared PP/PE blends and PPP/PE alloy,and analyzed the corresponding mechanism,as well as the mechanical properties.The results show that,after plasma treated,the concentration of free radicals of PPP was up to 10-8mol/cm2.The surface elements content as well as oxygen-containing groups after plasma treated were characterized by X-ray photoelectron spectroscopy(XPS).The water contact angle of PP was significantly decreased and the surface energy increased.The morphologies of PPP in different conditions were characterized by Scanning electron microscopy(SEM).It was found that various wrinkles appeared on the surface of PPP,and the period of the fold is gradually becoming smaller with the increase of discharge power.Due to the combined effect of internal stress and thermal expansion coefficient,the morphology of the surface is different on other substrates.The morphology and dispersion of PP/PE blends and PP/PE alloy were characterized by SEM.The results show that the phase dispersion of the two phases in the alloy is uniform and the interface is blurred.X-ray optical diffraction(WAXD)results show that the plasma treatment can not affect the crystal structure of the polymer or the alloy.The light scattering characteristic parameters of small angle X-ray scattering(SAXS)showed the phase morphology changes using integral invariant Q,correlation distance ac and average chord lengths L,after plasma treating,the PE phase dimension dispersed more uniform,phase distance became smaller,the interaction between PP and PE two-phase enhanced,and the interfacial layer thickness increased.Exclusion of Ar plasma on the interface layer,PP and PE compatibility was effected by ethylene plasma.The mechanical properties of the materials showed that the mechanical properties of the system are closely related to its mesoscopic structure.The distribution of the dispersed phase particles is more uniform than that of the PP/PE blend system.In the case of the tensile properties,including the young's modulus and the yield strength,the impact performance is greatly improved by adding less PE.