Evaluating thermal properties and activation energy of phthalonitrile using sulfur-containing curing agents

Abstract This work used the Kissinger equation to compute the activation energy of phthalonitrile to observe thermal properties. We initiated our investigation by synthesizing phthalonitrile samples, incorporating sulfur-containing curing agents ranging from 2 to 10%. Energy-dispersive X-ray spectroscopy confirmed the success of the curing process. Subsequently, we used thermogravimetric analysis (TGA) to acquire the necessary dataset for input into the Kissinger equation. The TGA results pointed to a direct relationship between the concentration of the curing agent and the thermal stability of the samples. Specifically, a sample treated with a 2% sulfur-containing curing agent demonstrated a moderate thermal stability (Td5%: 527.11°C). However, samples treated with higher concentrations of the curing agent, namely, 5 and 10%, exhibited increased Td5% values of 532.75 and 540.01°C, respectively. The increased thermal degradation-onset temperatures suggest a boost in the cross-linking density and mechanical properties, a result of the increased curing agent concentration. Further substantiating these findings, the Kissinger equation yielded high activation energies of 43.6222, 46.1365, and 67.9515 kcal·mol −1 for the 2, 5, and 10% curing agent dosages, respectively, with R ² values ranging from 0.9650 to 0.9701.