Surface analysis and printability studies on electron beam-irradiated thermoplastic elastomeric films from LDPE and EVA blends

The electron beam-initiated surface modification of films prepared from var ious blends of low-density polyethylene (LDPE), ethylene vinyl acetate (EVA ), and ditrimethylol propane tetraacrylate (DTMPTA) was carried out over a range of radiation doses (20-500 kGy) and concentrations of DTMPTA. The fil ms were characterized by Fourier transform infrared-attenuated total reflec tance (FT-ATR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanni ng electron microscopy (SEM), contact angle measurements, and peel adhesion . The printability of the films was also measured. FT-ATR and XPS revealed that the surface polarity of the films made from a 50:50 blend of LDPE and EVA increased up to a radiation dose of 100 kGy, compared with the unirradi ated sample. The polarity decreased after 100 kGy radiation. Surface pittin g and roughness were observed in the SEM photomicrographs of the same films , irradiated at higher radiation doses. Higher values of the surface energy were obtained at 100 kGy for the samples without DTMPTA and for the sample s containing 3 wt% DTMPTA. Excellent printability was observed for all the films irradiated above an irradiation dose of 20 kGy. The data on the print ability and peel adhesion of the irradiated films could be explained by sur face energy, XPS, and SEM results.