Improvement of Adhesive Strength of Polyacetal by Irradiation of Vacuum Ultra-Violet Light and Deposition of Nanometer-Sized Particles Simultaneously using Laser Ablation

Abstract

Polyacetal is a resin which has excellent property. However, polyacetal has a poor adherence property using adhesive material. Therefore, for the improvement of the adhesive strength, simultaneous surface treatments of polyacetal by irradiation of vacuum ultra-violet (VUV) light and deposition of nanometer-sized particles using laser ablation with C, Si and Ti targets were carried out. The surface treatments were carried out with different wavelengths, energies, processing times and substrate locations from normal direction of targets. The targets were irradiated with a pulsed laser from Nd-YAG laser. After surface treatments, tensile test pieces of polyacetal were bonded by epoxide-based adhesive. And, longitudinal shear strengths were measured. As a result, after surface treatment of polyacetal using C target, the highest shear bond strength which is approximately 8 times larger than that of untreated polyacetal sample was measured (5.6 MPa). It was found that increasing functional groups and increasing surface roughness are affecting improvement of the adhesive strength. The improvement of the adhesive strength is also caused by the new-creation of the dangling-bonds on the polymer surface by VUV irradiation and preservation of each dangling-bonds from re-bonding each other by a separation effect of deposited nanometer-sized particles. This method can be expected for new applications of polymers.