Mechanical properties, thermal stability, and thermal degradation kinetics of silicone rubber/ethylene‐vinyl acetate copolymer/magnesium sulfate whisker composites compatibilized by ethylene‐acrylic acid copolymer

Silicone rubber/ethylene‐vinyl acetate copolymer/magnesium sulfate whisker composites containing ethylene‐acrylic acid copolymer (MS/SR/EVM/EAA) as a compatibilizer were successfully prepared. Moreover, the magnesium sulfate whisker surface was modified with 3 wt% of silane coupling agent (KH570), resulting in composites including (unmodified magnesium sulfate whisker) uMS/SR/EVM, (modified magnesium sulfate whisker) mMS/SR/EVM, and mMS/SR/EVM/EAA were compared. The values of thermal decomposition activation energy (Ea) calculated by the two different methods (Kissinger and Friedman methods) show that the composites filled with 5 and 20 phr whiskers have lower values of activation energy (Ea) than the SR/EVM blend. The tensile strength of composites with a 5 phr modified whisker is 14.5 MPa, which is higher than that of the SR/EVM blend and uMS5/SR/EVM composite. The tear strength of the composite with 20 phr mMS is 51.6 kN m−1, much higher than that of the composite with 20 phr uMS and SR/EVM blend. The mechanical properties were also investigated after thermal aging of the composites at 85°C for 48 h. The thermal conductivity of the composites with high filler loading was studied. MS whisker modified by a coupling agent Step 1: KH570, Step 2: interfacial interaction between modified. whisker, EAA, and SR/EVM matrix.