Applied Surface Science, Vol.307, 109-119, 2014
Influence of non-thermal plasma forming gases on improvement of surface properties of low density polyethylene (LDPE)
Owing to the superior physico-chemical properties, the low density polyethylene (LDPE) has been widely used in the various industrial applications; especially in biomedical field for artificial organs, medical devices and disposable clinical apparatus. However, the poor anticoagulation property is one of the main drawbacks of the LDPE due to its poor surface properties. Therefore, in this paper we present the effect of plasma forming gases such as argon (Ar), oxygen (02), air and argon-oxygen (Ar + 02) mixture on improvement of the surfaces properties of LDPE film using direct current (dc) excited glow discharge plasma. Contact angle with evaluation of surface energy, X-ray photo electron spectroscopy (XPS), atomic force microscopy (AFM) techniques were used to examine the change in surface properties such as hydrophilicity, chemical composition and surface topography, respectively. Furthermore, the hydrophobic recovery of the plasma treated LDPE was analyzed using ageing effect under different storage condition i.e. in air and water. The adhesive strength of the LDPE films was determined using T-peel test. In vitro tests were used to examine the blood compatibility of the surface modified LDPE films. It has been found that the hydrophilicity of the various plasma treated LDPE films was improved significantly due to the formation of oxygen containing polar groups such as OH, COO, C-0, C=0 as confirmed by contact angle and XPS analysis. AFM revealed the changes in surface topography of plasma processed films. The gas mixture Ar + 02 plasma influenced the remarkable improvement on the surface properties of a LDPE film compared with other gaseous plasmas. These physiochemical changes induced by the plasma on the surface facilitate to improve the adhesive strength and blood compatibility. 2014 Elsevier B.V. All rights reserved.