The effects of the contents of modified-diatomite on the properties of modified-diatomite/epoxy resin composites

External plasticization is one of the effective ways to toughen epoxy resins. In this study, an inorganic filler (EMD) was prepared by chemical modification of diatomite and was used to fill epoxy resin matrix. The effects of different amounts (5%, 10%, 15%, and 20%) of raw diatomite (RD) and modified-diatomite (EMD) on the mechanical and thermal properties of epoxy resin composites were studied. The mechanical results showed that the impact strength, tensile strength, and bending strength of EMD/EP were higher than those of RD/EP. The impact strength of EMD-15/EP reached 5.39 KJ/m2, which was 36.8% higher than that of RD-15/EP. Thermogravimetric analysis showed that the thermal stability of EMD/EP was better than that of RD/EP. The results of DMA show that the glass transition temperature of EMD/EP was lower than that of RD/EP. Non-isothermal differential scanning calorimetry study showed that the apparent activation energy of EMD-15/EP was much lower than that of RD-15/EP, which proved that EMD could promote the curing of epoxy resin. The Malek method was used to determine that both the RD-15/EP and EMD-15/EP curing systems were autocatalytic (Šesták–Berggren) models. © 2024 Wiley Periodicals LLC.