Curing and pyrolysis of boron-modified phenolic resin

The curing kinetics, curing mechanism and pyrolysis of boron-modified phenolic resin were investigated by means of non-isothermal DSC technique, Ozawa method, solid-state ¹³C nuclear magnetic resonance (NMR), infrared spectrum (IR), pyrolysis-gas chromatography (Py-GC)and XRD. The results show that the approximate theoretical temperatures of gel, cure and post-treatment are 350.0 K, 386.2 K and 433.3 K, respectively. Its apparent activation energy at exothermic peak is 152.4 kJ/mol. The curing process involves the reactions of PhCH₂—OH to itself, PhCH₂—OH to B—OH, PhCH₂—OH to H of phenol ring as well as disproportionation of ether link. The mass loss at the range of 500 ℃ to 800 ℃ in the pyrolysis is 14.9%, and the pyrolysis products are mainly volatile compounds, such as CO, CO₂, H₂O, benzene and toluene. The residual carbon value at 1000 ℃ is 67.2%. The boron-modified phenolic resin is pyrolyzed into glass carbon after the heat-treatment at 1000 ℃ for 30 min.