Air Plasma-Activated Crosslinking of Low-Density Polyethylene During Melt Mixing

In this work, air plasma surface treatment followed by oxidation in an atmospheric environment was used to generate activated low-density polyethylene (LDPE) with oxygen-containing functional groups and peroxide radicals. The resulting samples were then studied by using attenuated total internal reflectance–Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and the 2,2-diphenyl-1-picrylhydrazyl method. Peroxide radicals are generally considered active substances which can initiate the crosslinking reaction. Melt mixing of the surface-treated LDPE allowed activated polymer chains with peroxide radicals to initiate the crosslinking reaction, and the maximum gel fraction obtained was 4.1%. The rheological behaviors, including viscosity, storage and loss moduli, loss tangent, and Cole–Cole plots, of the slightly crosslinked LDPE were studied, and the results of tensile experiments revealed that the formation of slightly crosslinked structures can improve yield and fracture stresses without sacrificing the breakage strain.