Creation of Adhesive Force between Laminated Sheets of Polytetrafluoroethylene (PTFE) and Polyethylene (PE) by Homogeneous Low Energy Electron Beam Irradiation Prior to Hot-Press for Bio-Adaptable Application

Abstract

Bio-adaptable 2-layer polytetrafluoroethylene/polyethylene (PTFE/PE) laminated sheets were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (¼0.43MGy) homogeneous low energy electron beam irradiation (HLEBI) to the 2-layer assembly where the HLEBI penetrates through the PTFE and PE layers, respectively, prior to hot-press under 5MPa and 433K. Although the adhesion of the PTFE/PE sheets cannot be observed without the new double-step treatment, bonding forces were created as evidenced by the mean adhesive forces of peeling resistance ( o Fp). The adhesion cannot be observed without HLEBI. On the other hand, application of a small dose of HLEBI (less than 0.43MGy) prior to hot-press lamination enhances the o Fp at each Pp. The maximum o Fp values at each Pp (0.06, 0.50 and 0.94) of the laminated sheet irradiated at 0.13, 0.13, and 0.22MGy are 5.44, 10.7, and 19.7Nm ¹1 , respectively. Based on the 3-parameter Weibull equation, the lowest o Fp value at Pp of zero (Fs) could be estimated. An increasing trend in Fs occurs by the double-step treatment applying HLEBI up to 0.43MGy reaching a maximum at 2.66Nm¹1, improving the safety level without radiation damage of PTFE/PE. It was more than 6 times higher than that of PTFE/Polyurethane (PU) (0.4Nm ¹1 ). When HLEBI cuts the chemical bonds and generates dangling bonds with nonbonding electrons in PTFE and PE, the created adhesion between the laminated sheets can be explained. Based on X-ray photoelectron spectrometer (XPS) surface analysis of the PTFE/PE laminated sheets after the peeling tests, fluorine (F) was detected on the PE peeled surface, indicating both strong chemical and intermolecular bonds generated by the double-step treatment. For these reasons, double-step treatment is a useful method for quick lamination of PTFE and PE with sterilization without the use of glue. [doi:10.2320/matertrans.M2013247]