No abstract

Mechanical and surface properties are considered important in governing the physical strength of polymers. A commercially available oxo-biodegradable polymer additive, which has induced surface and mechanical property changes during photo-oxidation in low-density polyethylene (LDPE) films, has been studied. LDPE films containing the oxo-biodegradable additive were irradiated with ultraviolet (UV)-B lamps at 30 ± 1 1C for an extended time period. The changes manifested on the polymer surface and in the mechanical properties were studied with respect to surface wettability, surface morphology using scanning electron microscope, surface topology by atomic force microscopy, functional groups by Fourier transformed infrared spectroscopy, absorbance spectra by UV-visible spectroscopy and elongation at break and tensile strength through mechanical testing. The increase in the wettability and surface-free energy of the irradiated samples was attributed to the formation of hydrophilic groups on the polymer surface by photo-oxidation, which occurs by the exposure of PE to UV irradiation in the presence of air. The degree of reduction in the mechanical strength and surface property modifications in our study are appreciable through the use of an oxo-biodegradable additive added to LDPE film samples.

The present work deals with the change in surface properties of polyethylene (PE) film using DC low pressure glow discharge air plasma and makes it useful for technical applications. The change in hydrophilicity of the modified PE film surface was investigated by measuring contact angle and surface energy as a function of exposure time. Changes in the morphological and chemical composition of PE films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap-shear strength. The results show that the wettability and surface energy of the PE film has been improved due to the introduction of oxygen-containing polar groups and an increase in surface roughness. The XPS result clearly shows the increase in concentration of oxygen content and the formation of polar groups on the polymer surface. The AFM observation on PE film shows that the roughness of the surface increased due to plasma treatment. The above morphological and chemical changes enhanced the adhesive properties of the PE film surfaces, which was confirmed by T-peel and lap-shear tests.