Fecha de publicación: -- Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Balancing low curing exotherm with high insulation performance remains challenging for chain-extended epoxy resins. Catalyst selectivity offers an effective route: TEBAC promotes moderate branching and lowers the curing activation barrier, favoring improved network uniformity and enabling simultaneous enhancement of glass-transition temperature, impact toughness, and dielectric breakdown performance.

ABSTRACT
For ultra-high-voltage thick-section epoxy insulation, reducing curing exotherm without compromising comprehensive performance remains a major challenge. This challenge is closely associated with the molecular architecture developed during chain extension and the cross-linked network formed during subsequent curing. Herein, two commonly used chain-extension catalysts, triethylbenzylammonium chloride (TEBAC) and triphenylphosphine (PPh3), were systematically investigated to clarify their roles throughout the chain-extension and curing process. TEBAC promotes the further reaction of secondary hydroxyl groups, producing a moderately branched molecular architecture while maintaining a low epoxy value of 0.30 eq/100 g. During subsequent curing, TEBAC exhibits a lower apparent activation energy and lower curing-temperature range than PPh3, favoring a higher degree of curing under identical conditions. Consequently, the mEP/TEBAC system exhibits substantially improved overall performance compared with the commercial epoxy resin, with impact strength, glass transition temperature, and volume resistivity increased from 13.97 to 29.82 kJ m−2, 111.6°C to 130.4°C, and 0.55 × 1017 to 1.08 × 1017 Ω cm, respectively. These results demonstrate that chain-extension catalysts can influence not only the molecular architecture formed during chain extension but also the subsequent curing behavior, establishing a direct link between catalyst selection, molecular structure, curing process, and final properties.