Research on the Alcohololysis Kinetic of Anhydridecured Epoxy Resins

Anhydride-cured epoxy resins (EP) are essential in power equipment owing to their superior electrical insulation properties, but their three-dimensional cross-linked network poses formidable recycling challenges, resulting in substantial environmental harm from conventional disposal methods (e.g., landfill or incineration). While selective alcoholysis presents a sustainable alternative by cleaving ester bonds under mild reaction conditions, prior investigations focus on small-scale resin particles, overlooking industrial applicability. This study bridges this critical gap by systematically investigating the alcoholysis kinetics of industrially relevant 10 mm epoxy cubes, enabling the development of a comprehensive kinetic model that incorporates solvent diffusion and transesterification. Degradation experiments of the epoxy cubes are conducted at 105,120, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$135{ }^{\circ} \mathrm{C}$</tex> using ethanol and catalyst <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{K}_{3} \text{PO}_{4}$</tex>, with time-dependent mass loss profiles recorded. Through rigorous mathematical derivation, the alcoholysis kinetic equation is obtained, experimentally validated through comparative analysis, and successfully employed to predict mass changes during EP degradation at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$150{ }^{\circ} \mathrm{C}$</tex>. Finally, the alcoholysis products are characterized, with the hydroxyl value (477.4 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{m g K O H} / \mathrm{g}$</tex>) demonstrating their viability for direct reuse in synthesizing high-performance epoxy resins or polyurethanes. This work validates the model's accuracy for large resin particle degradation, reducing pre-crushing energy demands.