High carbon yield thermoset resin based on phenolic resin, hyperbranched polyborate, and paraformaldehyde

Hyperbranched polyborate (HBPB) is a new hyperbranched polymer with excellent thermal resistance, which can be used to improve the thermal stability, especially carbon yield, of phenolic resin (PR). In the present paper, thermal properties and curing degrees of the blends of PR and HBPB (PR-HBPB blends) are investigated. It is found that the curing degrees of PR-HBPB blends would be decreased, and the decrease of curing degree can be attributed to the improper ratio of phenol groups of HBPB to hydroxymethyl groups of PR. Paraformaldehyde (PFM) is introduced to remedy the deficiency of hydroxymethyl groups in PR-HBPB blends. The curing degrees of PR-HBPB blends are improved and the carbon yields of the blends of PR, HBPB, and PFM (PR-HBPB-PFM blends) can be up to 75-80% at 800°C in nitrogen. PR-HBPB-PFM blends can be explored as novel precursors for carbon materials with excellent properties, ease of preparation and low cost.