Strength of vibration-welded polycarbonate-poly(butylene terephthalate)-blend butt welds

In vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. Previous work characterized the effects of factors such as weld frequency, weld pressure, and weld time on the welding process and weld strength, and showed that the most important factor affecting weld strength of neat resins is the weld penetration—the decrease in the distance between the parts being welded that is caused by lateral outflow of material in the molten film. This paper is concerned with strengths of vibration-welded butt joints of polycarbonate-poly(butylene terephthalate) blends. Weld strengths were mapped at room temperature and at −29°C at strain rates of 0.25 × 10 −2s −1 and 0.25 s −1. It was possible to achieve weld strengths equal to that of the base material. Tests on two blends showed that the low-temperature and high-strain-rate strengths and strains at failure can be significantly improved by changing the content of impact modifiers.