Preparation and properties of acetylene-functional benzoxazines with comparative phenol sources

Abstract

High heat-resistant polymer materials are required urgently as the fast development of the aerospace field. The cross-linking characteristic of polymers with the acetylene group provides us with an effective strategy. Here, a series of acetylene-functional benzoxazine monomers with different phenolic compounds, TERT-apa, BA-apa and THPE-apa, were synthesized, and their chemical structures were confirmed by Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) spectra. Their curing behaviors and polymerization reactions were analyzed by differential scanning calorimetry (DSC) and FTIR technology, and possible cross-linking structures were proposed. Meanwhile, their gelation reaction activation energies were obtained by the gelation time test. After curing at 200°C, the thermal properties of these cured polybenzoxazines were studied by Dynamic mechanical analysis (DMA) and Thermogravimetric analysis (TGA). Among them, the glass transition temperature (T_g) of p(BA-apa) can reach as high as 428°C, while p(THPE-apa) had a weight loss temperature over 400°C and a char yield of 60% at 800°C under N₂. Therefore, this study shows that the introduction of the acetylene groups is a effective strategy for the preparation of high-performance polymers, which provides some promising high heat resistant materials for the aerospace field.