Apr 24, 2022 · HDPE at 20C° and LDPE at 50C° show effect after 7 days. HDPE at 50C° shows immediate damage and is not rOkaymmended. Nitric acid 70 % HDPE and LDPE at 20C° show some effect after 7 days. Both at 50C° show immediate damage and are not rOkaymmended. Oleic acid HDPE at 20C°-50C° show little or no damage after 30 days of nstant exposure.