Research on Montmorillonite Solid Superacid Modified Flame Retardant Unsaturated Polyester Resin

Solid superacid possesses high acidity and thermal stability, which can effectively improve the flame retardant properties of materials by promoting catalytic dehydration and charring. On the other hand, montmorillonite (MMT) has a good synergistic effect with the flame retardant due to its unique two-dimensional nanosheet structure. To combine both advantages to get high performance, in this study, a solid superacid structure was introduced into the MMT to obtain a montmorillonite solid superacid (Ti-MSS). Its structure, morphology, and acidity were characterized by XRD, EDS, TEM, and Hammett indicator method. This Ti-MSS was then combined with ammonium polyphosphate (APP) for the flame retardant treatment of unsaturated polyester resin (UPR). The results showed that when the UPR composite containing 0.1 wt% Ti-MSS and 9.9 wt% APP, its limiting oxygen index (LOI) value reached 28.9%, and UL-94 achieved a V-0 rating. CCT data showed that, compared with the APP/UPR composites, the peak heat release rate and total heat release were reduced by 8.99% and 12.47%, respectively. Moreover, smoke and gas release were also reduced after the addition of Ti-MSS. TG, SEM, XPS, and Raman data results showed that Ti-MSS promoted carbonization of the UPR to obtain more residual char and make it more continuous and denser. It was suggested that Ti-MSS had a good synergistic flame retardant effect with APP on UPR.