high solid contene polymerization of methyl methacrylate(MMA) with free radical initiator is the chosen model system for the investigation of diffusion-controlled bimolecular termination and prooagation and the decrease in initiator efficiency at high monomer conversions(cage effect). it has the largest trommsdorff-norrish effect because most of the polymer chains are produced by bimolecular termination and the higher-average molecular masses increase dramatically in the absence of a chain-transfer agent. the MMA polymerization reaction, measured by differential scanning calorimetry at two different temperatures and modeled according to fleury et al. and zeilmann ยกกำลัง2,3, is presented in Figure 1. The gel or trommsdorff-norrish effect(being accepted as a polymerization rate auto-acceleration) is clearly observable at 135 องศาเซลเซียส. starting after 250 s and being less present at 155 องศาเซลเซียส. the reaction time to complete the MMA polymerization is about 14 and 30 min at 155 and 135 องศาเซลเซียส, respectively the correlation between the experiments and the model is really good, indicating that the parameters and the model describe well the observed measurements. this suggests that this model could be used for the scale-up/-down study. therefore it is necessary to have a reliable kinetic model before accepting too many compromises that could lead to wrong development and expectations.