Study of Ultrasonic Welding of Glass Fiber Reinforced Thermosetting Epoxy-based Polymers

This paper presents the preliminary results of ultrasonic welding of epoxy- based thermosets by thermoplastic interlayers. The main objective is to understand the possible mechanisms of interfacial adhesion and also to explore feasible approaches such as application of pretreatment processes as cost-effective manufacturing techniques.Therefore, sulfuric acid (H2SO4) solution is employed as an etchant to remove outer epoxy layers and pretreat chemically the surface of thermoset composite for subsequent welding process. The polyvinyl chloride (PVC) and polymethylmethacrylate (PMMA) are used between two thermoset composites as interlayers to bond the thermoset composites by using the ultrasonic welding with a frequency of 15 KHz directed to the workpieces through predesigned mechanical horn. Finally, for the case of PVC interlayer, application of 2 bar pressure, 1.2 s welding time and 3 s holding time selected as welding parameters, the maximum tensile stress is determined to be about 76.9 MPa. In contrast, for the case of PMMA interlayer, 2 bar pressure, 2 s welding time and 3 s holding time as welding parameters, the minimum tensile stress is about 14.8 MPa. So, experimental investigations reveal that ultrasonic welding can be effectively applied in industrial aspects.

Keywords:

Ultrasonic welding , Thermoset and thermoplastic polymers , PVC , PMMA , Epoxy resin