Modeling of Styrene/Butadiene Co‐polymerization in Emulsion with Monte Carlo Simulation

Abstract

Communications of the primary particle diameter determined with LII and the CTAB number ± the specific surface without consideration of micropores ± is observable. The error bars result from the standard deviations of the average values. It should be noted that the size of the standard deviation is determined by fluctuations of the particle size, i.e. among other things by reactor fluctuations, and is not a characteristic of the measuring technique as already shown beyond doubt in laboratory tests at stationary objects. ConclusionsThe investigations proved the applicability of the laserinduced incandescence technique for the on-line characterization of carbon blacks, which holds for both the application of the measuring technique in an industrial environment in principle and the successful in-situ measurement of primary particle sizes. In particular the investigations with fine parameter variations clearly show that LII represents a very good tool for direct process control without time delay. Changes in the primary particle size and/or disturbances during the process can be detected with LII practically immediately. A correlation between the primary particle size d P measured by means of LII and the CTAB number could be found. A connection between the iodine number and LII results is not clearly given, i.e., differences in the porosity which determines the iodine number among other things, without changes in particle size (characterized by the CTAB number) are not determined with LII. These results seriously underline the thesis that with LII a measure for the enveloping specific surface area is determined. Little experimental effort makes the employment of a LII sensor particularly interesting for process control. Apart from the quantitative determination of the primary particle size the measuring technique is very helpful also to decide whether an operating condition of the reactor has already stabilized and/or behaves stationarily. Small fluctuations, in particular of periodic kind, can be detected very well by the possibility of a continuous measurement where values are taken with a frequency of up to 20 Hz. Communications which include: Interval I is finished when all micelles have disappeared, the rate of monomer addition depends only on the nature of the terminal group. During the polymerization period no variation is considered for the reaction constants. A bimodal molecular weight distribution was obtained, which is evidence of tri-functional branching and tetra-functional crosslinking. The results show an increase in the degree of conversion, which leads to a shift in the molecular weight distribution toward higher values. An increase in the emulsifier concentration increases the surface area under the second peak in the molecular weight distribution. The MC simulation as a statistical approach, gave results that are in agreement with the Smith-Ewart theory for insoluble monomers in continuous media.

Progress in Computer Simulation of Bulk, Confined, and Surface‐initiated Polymerizations

“…Tobita assumes steady state between entry and desorption of radicals in emulsion droplets, using either empirical relations,108 or the more complex Smith‐Ewart equations109 to estimate the average number of radicals per particle. In another study, capture of oligoradicals by micelles is diffusion limited according to the Smoluchowski equation 110. Radical desorption from particles is also considered to be diffusion‐limited.…”