A study on the curing kinetics of epoxycyclohexyl polyhedral oligomeric silsesquioxanes and hydrogenated carboxylated nitrile rubber by dynamic differential scanning calorimetry

A new organic–inorganic hybrid material was prepared through reactive blending of hydrogenated carboxylated nitrile rubber (HXNBR) with epoxycyclohexyl polyhedral oligomeric silsesquioxanes (epoxycyclohexyl POSS). The structure of the composite was characterized by Fourier transform infrared spectroscopy (FTIR) and solid‐state 13C Nuclear Magnetic Resonance spectra (solid‐state 13C‐NMR). The differential scanning calorimetry (DSC) at different heating rates was conducted to investigate the curing kinetics. A single overall curing process by an nth‐order function (1 − α)n was considered, and multiple‐heating‐rate models (Kissinger, Flynn–Wall–Ozawa, and Crane methods) and the single‐heating‐rate model were employed. The apparent activation energy (Ea) obtained showed dependence on the POSS content and the heating rate (β). The overall reaction order n was practically constant and close to 1. The isoconversion Flynn–Wall–Ozawa method was also performed and fit well in the study. With the single‐heating‐rate model, the average Ea for the compound with a certain POSS content, 66.90–104.13 kJ/mol was greater than that obtained with Kissinger and Flynn–Wall–Ozawa methods. Furthermore, the calculated reaction rate (dα/dt) versus temperature curves fit with the experimental data.