Synergistic crosslinking of phenolic-epoxy for denser networks with enhanced thermal–mechanical properties

作者：Chen Sang, Wenmu Yang, Wenkai Chang, Bingnong Jiang, Cheng Wang, Cheng Wang, Yingkun Sheng, Shuhua Peng, Jin Zhang, S. A. Brown, Chun Hui Wang, Chun Hui Wang, Zhao Sha · 发表于：Advanced Composites and Hybrid Materials · 年份：2026 · DOI：10.1007/s42114-025-01513-9 · 被引用次数：4 · 研究领域：Flame retardant materials and properties、Epoxy Resin Curing Processes、Synthesis and properties of polymers

Phenolic polymers are widely used for fire-resistant applications but suffer from high porosity and low fracture toughness, limiting their structural performance. To address these challenges, we propose a catalyst-free approach to crosslink phenolic with epoxy, forming hybrid polymers with denser networks, reduced porosity, and enhanced thermal–mechanical properties. A systematic study examined the influence of phenolic-to-epoxy resin ratios on curing kinetics, mechanical properties, and thermal stability. The optimal formulation, comprising 75 wt.% phenolic and 25 wt.% epoxy, achieved a dramatic porosity reduction (0.9% versus 52.5% for catalyst-cured phenolic) and a char yield of 52.5%, exceeding the rule-of-mixture prediction by 23.5% and approaching pure phenolic (54.4%). This hybrid exhibited a 158% increase in initiation fracture toughness (0.169 kJ/m 2 ) and a 17% improvement in the flexural strength (406.8 MPa) of carbon-fibre-reinforced composites at room temperature. Moreover, after exposure to 50 kW/m 2 heat flux for 30 s, the composites retained 48% higher flexural strength (291.5 MPa) than those with pure phenolic (196.9 MPa). These significant improvements are attributed to the synergistic effects of reduced porosity and a stable epoxy-phenolic network, delivering superior mechanical performance without compromising flame resistance. The findings demonstrate the potential of phenolic-epoxy hybrids for high-temperature, fire resistant applications requiring robus...