Thermal behavior and Fire resistant properties of Vinyl Ester Resines Modified with Dimethyl Methylphosphonate and Diatomite

The thermal behavior and flame-retardant performance of vinyl ester resins (VER) modified with dimethyl methylphosphonate (DMMP) and diatomite (DE) were investigated. Differential Scanning Calorimetry (DSC) was performed using a NETZSCH DSC 300 Caliris Select instrument (Germany). Measurements were conducted in Concavus aluminum crucibles under a nitrogen atmosphere with a constant flow rate of 40 mL/min. VER was modified using three types of fillers: DE alone, a physical mixture of DMMP and DE, and DMMP immobilized on DE. These modifications resulted in distinct values for glass transition temperature, glass transition range, and heat capacity change (∆Cp). These parameters provide insight into the chain mobility and flame-retardant properties of the materials. The narrow transition range and lowest ∆Cp observed for the immobilized DMMP sample indicate the increase in thermal stability of the material compared to the other samples, which corresponds with the LOI and flammability tests. This includes increased decomposition temperature and enhanced char formation, offering improved protection under real fire conditions. These results demonstrate the effectiveness of modifying VER with immobilized DMMP as a strategy for producing flame-retardant materials and may provide guidance for the development of new fire-safe composites.