Chapter 19. Reaction Calorimetry for the Development of Ultrasound-Induced Polymerization Processes in CO_2-Expanded Fluids

摘要

A strong viscosity increase upon polymerization hinders radical formation during an ultrasound-induced bulk polymerization. Since CO_2 acts as a strong anti-solvent for most polymers, it can be used to reduce the viscosity of the reaction mixture. In this work, a process for the ultrasound-induced polymerization in CO_2-expanded fluids has been developed. Temperature oscillation calorimetry has been applied to study the influence of CO_2 on the viscosity during the ultrasound-induced polymerization. In contrast to polymerizations in bulk, the results show that a low viscosity is maintained during polymerization reactions in CO_2-expanded methyl methacrylate (MMA). As a consequence, a constant or even increasing polymerization rate is observed when pressurized CO_2 is applied. Moreover, the ultrasound-induced polymer scission in CO_2-expanded MMA is demonstrated, which appears to be a highly controlled process. Finally, a preliminary sustainable process design is presented for the production of 10 kg/hour pure PMMA (specialty product) in CO_2-expanded MMA by ultrasound-induced initiation.Get PDF (269K)