2014 Volume 55 Issue 3 Pages 566-571
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 (≦0.43 MGy) 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 5 MPa and 433 K. 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 (oFp). The adhesion cannot be observed without HLEBI. On the other hand, application of a small dose of HLEBI (less than 0.43 MGy) prior to hot-press lamination enhances the oFp at each Pp. The maximum oFp values at each Pp (0.06, 0.50 and 0.94) of the laminated sheet irradiated at 0.13, 0.13, and 0.22 MGy are 5.44, 10.7, and 19.7 Nm−1, respectively. Based on the 3-parameter Weibull equation, the lowest oFp value at Pp of zero (Fs) could be estimated. An increasing trend in Fs occurs by the double-step treatment applying HLEBI up to 0.43 MGy reaching a maximum at 2.66 Nm−1, improving the safety level without radiation damage of PTFE/PE. It was more than 6 times higher than that of PTFE/Polyurethane (PU) (0.4 Nm−1). 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.