A simple model for the semicontinuous heterophase polymerization: Ethyl methacrylate as a case example

Abstract

A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately describes the overall and instantaneous conversion, the average particle density and diameter, and the number and weight average molar masses evolutions over time. It is found that even though the average number of radicals is much smaller than 0.5, the system is not 0-1. An empirical function was used to describe the gel effect. The homogeneous nucleation was the prevailing mechanism for particle formation and large exit rates of radicals were observed. POLYM. ENG. SCI., 60:223-232, 2020. 225 FIG. 6. Number (M n ) and weight (M w ) average molar masses against dimensionless time. Experimental results represented by symbols and the lines are model fittings. R a = 0.22 g min −1 (squares/dotted lines); R a = 0.50 g min −1 (triangles/dashed lines); R a = 0.70 g min −1 (circles/continuous lines).

A piece-wise reconstruction of some mechanistic steps in Pickering emulsion polymerization: A semicontinuous styrene montmorilonite-supported process as a case example

“…1, it can be seen that a controlled starved process was not achieved, due to the fact that the conversion against time curve does not have a constant slope. This nding is in contrast to the work reported by Pérez-García et al [28] or in Alvarado et al [29].…”

“…In both gures it can be observed that, even with a semi-continuous process, two clear rate intervals are present, as opposed to the classic batch emulsion polymerization. As a matter of fact, in a semi-continuous starved process a constant rate of polymerization should be achieved [28,29]. Figure 4 shows that a master curve can be constructed when plotting rate of polymerization against conversion, where all the runs using clay lie almost on a single trajectory --making clear that the only outlier is the curve where no clay was used.…”