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Effect of dual track wedge welding at 30℃ ambient temperature on post-weld geomembrane oxidative induction time

High density polyethylene geomembranes are used extensively in barrier systems for land-fills and mining applications. The geomembrane panels are usually welded together using a duel track hot wedge welder, which can heat the geomembrane at the weld to temperatures in excess of 400℃. It has re-cently been reported that this can cause depletion of antioxidants and, at least in some cases, a potential reduction in service life of the geomembrane immediately adjacent to the weld. This paper describes ex-periments that examine the relationship between the ambient temperature and welding parameters (i.e., welding speed and welding temperature) and their effect on standard oxidative induction time (Std-OIT) for an HDPE geomembrane. The welding speed and temperature settings examined represent the range of acceptable values one would reasonably expect an operator to utilize for an ambient temperature of +30℃. Std-OIT test were performed on welded samples following ASTM D3895. Results show that all welds passed ASTM D6392 peel and shear tests and that Std-OIT values varied as much as 18.5 minutes (9%) depending on welding temperatures and speed.