Investigation on enhancement of weld strength between PMMA and PBT in laser transmission welding—Using intermediate material

Abstract

ABSTRACTPoly(methyl methacrylate) (PMMA) and poly(butylene terephthalate) (PBT) are widely used in industry; however, poor compatibility between two materials lead to poor weld strength. Polycarbonate (PC) has good compatibility with PMMA and PBT. Therefore, the welding method was that PC film as intermediate material was used to enhance weld strength in laser transmission welding (LTW) of PMMA and PBT. Through the LTW experiment, the weld strength was tested by mechanical testing and it was found that the best weld strength was improved more than four times than the weld strength without intermediate material. By observing the micro morphology of the weld zone, one reason was founded that the bubbles can be used to form micro‐mechanical riveting to enhance the weld strength. The reptation time for PMMA, PC, and PBT were investigated to analyze the establishment of the weld strength. When the reptation time is much shorter than time in molten state, the higher weld strength is feasible. It can be concluded that the weld strength of PC/PBT was higher than the weld strength of PMMA/PC. The equilibrium interfacial width was calculated through Helfand's theory to analyze the compatibility of dissimilar materials. The equilibrium interfacial width for PMMA/PC and PC/PBT were similar to tube diameter. That is the reason for weld strength enhancement. And then, the response surface methodology was designed to predict the weld strength.© 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44167.