Research on the Micro-Structural Evolution of Phenol-Formaldehyde Resin Modified by Boron Carbide

摘要

Phenol-formaldehyde (PF) resin usually could not be applied in the high-temperature environments due to its poor heat-resistance. Many kinds of modification methods had been presented in order to improve its stability of the structures and properties. In this paper, boron carbide (B_4C) was used as the modification additives to improve the residue of PF resin after being treated at high-temperatures. Thermal gravity (TG) and scanning electron microscopy (SEM) were employed to investigate the residue and micro-structural evolution of modified PF resin during the heat-treatment process. TG results demonstrated that the residue of PF resin was improved effectively due to the satisfactory modification effects of B_4C. SEM morphology showed that the distribution of B_4C powders became propertional at the elevated temperatures, and boron oxides (B_2O_3) was formed in the interior of PF resin matrix. These results indicated that there existed complex modification reactions between B_4C and volatiles released from the degradation of PF resin at high-temperatures. By means of the above modification reactions, some volatiles, especially for CO, converted into amorphous carbon and results in the increasing of residue after being treated at high-temperatures.