Chemical Recycling of High-Density Polyethylene (HDPE) Wastes by Oxidative Degradation to Dicarboxylic Acids and Their Use As Value-Added Curing Agents for Acrylate-Based Materials

•Chemical recycling of non-degradable polymers to functional materials to achieve a circular economy.•Hydrothermal nitric acid oxidation to convert HDPE waste to its small-sized value-added chemicals.•Optimization of reaction conditions: temperature, time, filling capacity, nitric acid concentration and HDPE/nitric acid ratio, to enhance product yields and diacid compositions.•Potential use as crosslinkers for UV-curable acrylate/ester-based adhesives.