Rheological study of diffusion-controlled crosslinking of poly(ethylene–octene) elastomer via peroxide-trapped fumed silica

The radical crosslinking process of poly(ethylene–octene) copolymer (POE) has been done by impregnating dicumyl peroxide (DCP) onto fumed silica. The examination of kinetic progress by means of linear viscoelastic measurements revealed modification in crosslinking kinetics process. First of all, the gel time is delayed when the peroxide is trapped in fumed silica. This reveals a new way for controlling the kinetics of a melt crosslinking reaction. The analysis of rheological kinetic curves and values of the equilibrium modulus, when the reaction is completed, showed that the competition between DCP diffusion and crosslinking reaction is not time dependent in the temperature range 145–170 °C. However, the POE crosslinking from trapped DCP in fumed silica particles leads to the formation of a less perfect network (the elastic modulus is 1.5 time lower and tan δ 1.7 higher) in comparison with a crosslinking reaction in homogeneous conditions.