Adhesive Force of Laminations of Titanium Untreated and Polycarbonate Homogeneously Irradiated by Low Potential Electron Beam Prior to Assembly and Hot-Press

Abstract

A 2-layer Titanium/polycarbonate (Ti/PC) laminated sheet treated by homogeneous low energy electron beam irradiation (HLEBI) to only the PC side prior to assembly and hot press at 438 K for 3.0 min under 20 MPa without the use of fasteners, rivets or glue was investigated. Experimental results showed the 0.30 MGy HLEBI dose appeared to be at or near the optimum, achieving mean adhesive force of peeling resistance, ^oF_p at high accumulative probability of peeling P_p = 0.94 of 141.4 Nm⁻¹ compared to 20.0 Nm⁻¹ for the untreated (without HLEBI). Notably, the 0.30 MGy HLEBI raised the ^oF_p at high- P_p of 0.94 significantly, 706%. Moreover, based on the 3-parameter Weibull equation, the 0.30 MGy-HLEBI apparently enhanced the statistically lowest ^oF_p (F_s) from 0 N·m⁻¹ for the untreated to 15.1 N·m⁻¹ for the 0.30 MGy samples, as well as at low-P_p of 0.06 (the lowest experimental ^oF_p) from 0 for the untreated to 25.5 N·m⁻¹ for the 0.30 MGy samples. Based on the results of XPS (X-ray photoelectron spectroscopy) analysis, chemical bonds occurred. When HLEBI cut the chemical bonds and generated active terminated atoms with dangling bonds at PC surface, they probably induced chemical bonding with the Ti. Furthermore, the HLEBI to only the PC side acted to generate the PC activating strong adhesion to the Ti making the interface stronger than the internal cohesion of the PC itself. In addition, 0.30 MGy-HLEBI apparently increased the active bonds sites of C-O and C-C and then decreased the inactive bonds sites of OH on the PC and Ti, resulting in strengthening the peeling resistance. Therefore, increasing adhesion force between the laminated sheets could be explained.