Study on the Morphologic and Flow State of Polyacrylonitrile Particles in a Microchannel Reactor

In this work, acrylonitrile and methyl acrylate copolymer [P(AN–MA)] was prepared by mixed solvent precipitation in a millimeter-scale microchannel reactor. In the range of 30 × 104–60 × 104 g/mol, P(AN–MA) is characterized by a controllable molecular weight and a narrow polydispersity index (<1.3). It was found that the composition of P(AN–MA) was controlled by the ratio of dimethyl sulfoxide (DMSO)/H2O of the mixed solvent. This resulted from the different solubilities of AN in various DMSO/H2O ratios of the mixed solvent, leading to the change of AN/MA involved in the polymerization. The content of MA in the P(AN–MA) increased with a higher H2O content in the mixed solvent. The polymerization process of P(AN–MA) in the microchannel reactor follows a tertiary granulation mechanism, as shown by the morphology of P(AN–MA) precipitated particles. In addition, the increase of H2O content in the mixed solvent is favorable to improving particle morphology. However, it is difficult to control the flow state of the particles in the pipeline with a high H2O content. Therefore, 60 wt % H2O content is the optimum process condition. On this basis, the sedimentation of particles on the reactor wall was reduced, and pipe clogging was significantly improved by process optimization.