Investigation of the effect of moisture intake of hot plate welded polyamide based materials on weld strength

In this study, samples made of PA6 and glass fiber reinforced derivatives, are welded by hot plate welding method using the optimum welding parameters obtained by our preliminary investigation. In order to investigate the effect of water absorption behavior on welding strength, the samples are conditioned artificially by keeping them in a temperature range of -20 to 60 degrees celsius for 2 to 16 hours. Depending on conditioning temperatures, significant variations are seen in the water absorption behavior and accordingly in mechanical properties of PA6, PA6 GF15 and PA6 GF30 type materials. It is observed that, in welded samples, increase in conditioning temperatures and durations, increased the water absorption rate of PA6 material, decreased the mechanical strength values and increased the elongation percentage values in welded samples. On the other hand in glass fiber reinforced samples, increase in conditioning temperatures and durations, decreased, the mechanical strength values, but increase in conditioning temperatures and durations did not cause a significant change on water absorption rate and elongation percent values. The highest welding strength measurements after conditioning were 32.9 MPa in PA6 material at -20 degrees celsius, 38.2 MPa in PA6 GF15 at -10 degrees celsius and 41.4 MPa in PA6 GF30 at 0 degrees celsius.