The kinetic of photoinitiated polymerization of a dimethacrylate oligomer was studied by using isothermal photocalorimetry. The reaction was realized with 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173) as radical photoinitiator. Two kinetic models were applied. First, it was shown that an autocatalytic model can describe this reaction in a satisfying way. The reaction temperature does not influence the m and n orders of the reaction which were found to be constant and respectively equal to 0.8 and 2. The phenomenological rate constant k varies with temperature according to the Arrhenius law up to 80°C. Above this temperature, this law can again be checked if the initial variation of double bond concentration due to thermal polymerization is taken into account. In addition, by means of a mechanistic model, the k p and k t rate constants were calculated. Their evolution with conversion was studied at 50°C and well illustrates the importance of the reactive diffusion mechanism.
Посилання на статтю:
Photoinitiated polymerization of a dimethacrylate oligomer: 2. Kinetic studies / L. Lecamp, B. Youssef, C. Bunel, P. Lebaudy // Polymer. – 1999. – N 40. – P. 1403–1409.