Triethanolamine–azodiisobutyronitrile mixture as a foaming agent for low‐density unsaturated polyester resin manufacturing at a low temperature

Abstract

ABSTRACTA triethanolamine (TEA)–azodiisobutyronitrile (AIBN) mixture was applied to the manufacturing of a low‐density unsaturated polyester resin (LDUPR) at a low temperature ranging from 53 to 66 °C. Hydrogen‐bonding activation in the TEA–AIBN mixture was put forward, and this agreed with the NMR and Fourier transform infrared (FTIR) spectroscopy results. A heat balance in the curing process of a vinyl ester unsaturated polyester resin (UPR) was examined and characterized by differential scanning calorimetry, FTIR spectroscopy, and scanning electron microscopy. The TEA–AIBN mixture decomposed easily because of the hydrogen‐bonding action between TEA and AIBN. The heat release of the activated AIBN decomposition led to the early endothermic polymerization of the vinyl ester UPR. Hydrogen‐bonding activation followed by the heat‐balance process enabled us to manufacture the LDUPR at low temperature. The optimal parameters of LDUPR manufacturing, including a ratio of TEA to AIBN of 0.4 and a dosage of TEA–AIBN mixture of 2.5 phr at a curing temperature of 60 ± 1 °C, were defined by the testing of the apparent density (ρ) and compressive strength of LDUPR. Under these conditions, ρ was 0.39 ± 0.01 g/cm3, and the specific compressive strength was 33.92 ± 1.31 MPa g−1 cm−3. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44797.