Chlorination reaction kinetics of the low-concentration natural rubber latex

The kinetics of the chlorination of low-concentration natural rubber latex was investigated. The kinetic data were derived from chlorine concentrations in chlorinated natural rubber (CNR) for different reaction times and temperatures. The chlorination reaction process can be divided into two stages-a high-speed period (stage 1) and a low-speed period (stage 2)-using the graphed curves of the change in chlorine content with change in reaction time. The relationship of the chlorination conversion ratio x to reaction time t and temperature T can be expressed as x=1.15 0.916e-kt, where the kinetic constant k=0.00907+6.3×310-6e0.0211T. The overall apparent reaction order n for the first stage is 4.8, whereas for the second stage it is 1.0, using kinetic fitting. The apparent activation energy Ea was calculated, using the Arrhenius equation, to be 5.32 kJ/mol for stage 2. The lower value of Ea suggests that the chlorination rate is less sensitive to reaction temperature in this stage. The chlorination reaction rate increases with the increase in reaction temperature during stage 2, but the effects are not visible. However, a temperature that is too high may result in energy being wasted. We conclude that the proper reaction temperature in stage 2, taking the kinetic effects into account, is between 323.15 and 353.15 K.