The effect of fillers on the vibration welding of poly(butylene terephthalate)

Two particulate-filled grades of poly(butylene terephthalate) (PBT) containing about 10 and 30 wt% mineral fillers, one particulate-filled polyester blend containing about 65 wt% mineral filler, and two glass-filled grades of PBT containing about 15 and 30 wt% glass fibres have been studied to assess the effects of fillers on the strength of vibration welded butt joints. The weldability of these materials has been characterized at weld frequencies of 120 and 250 Hz and weld pressures of 0.9 and 3.45 MPa. Each of these five materials is shown to exhibit the four phases of vibration welding that are common in unfilled resins. Welds of these five materials are shown to achieve strengths on the order of 89, 58, 85, 69 and 60% of the strengths of the base (filled) resins.