Hydrobromination of hydroxyl-terminated polybutadiene (HTPB) resin under optimal conditions with aqueous hydrobromic acid using response surface methodology (RSM)

In this paper, statistical analysis and experimental methods are employed to study the hydrobromination of hydroxyl-terminated polybutadiene (HTPB) elastomer by 48% hydrobromic acid. The effect of three variables including time, temperature, and volume of acid, on the percentage of hydrobromination is investigated. The influence of these parameters and their interaction is checked through the analysis of variance and sensitivity analysis, and the optimum values for 10% hydrobromination are obtained 24 h, 30 °C, and 5.05 ml of the acid volume. A hydrobrominated resin is synthesized by applying optimal conditions for hydrobromination of 10% of double bonds. The results obtained from classical analysis and NMR show the amount of hydrobromination as 9.89% and 9.38%, respectively. The placement of the bromine atom in the compound is confirmed by ATR and NMR analysis. Also, DSC analysis shows that the glass transition temperature (T_g) of the hydrobrominated product increased by 2.86 °C compared to the initial HTPB.