Combination of fumed silica with carbon black for simultaneously improving the thermal stability, flame retardancy and mechanical properties of polyethylene

The combination of fumed silica (SiO2) with carbon black (CB) for improving thermal stability, flame retardancy and mechanical properties of linear low density polyethylene (LLDPE) was investigated. The temperature at the maximum weight loss rate of LLDPE was dramatically increased by 92 degree C, and the peak value of heat release rate measured by cone calorimeter was significantly reduced by 80.7%. The improved thermal stability and flame retardancy of LLDPE were partially attributed to the formation of a percolated network structure in LLDPE matrix, and partially to the accelerated oxidation crosslinking reaction of LLDPE or other radicals by CB and SiO2. More importantly, although both SiO2 and CB were used without any pre-treatment, ternary LLDPE nanocomposites showed much higher mechanical properties compared to those of neat LLDPE. This was ascribed to good dispersions of two kinds of nanoparticles and strong matrix-nanoparticle interfacial interactions with LLDPE matrix.