Experimental procedure emulsion polymerization

Polyfvinyl acetate) (PVAc) latexes produced by batch and continuous emulsion polymerization were used in this study. Details for the apparatus and the polymerization procedure can be found in Penlidis et al. (6,12,K3). Samples taken during the reaction were subsequently analyzed to follow conversion- and particle growth-time histories. The batch experimental runs were designed to yield similar conversion-time histories but different particle sizes. Conversion was measured both off-line, by gravimetric analysis, and on-line using an on-line densitometer (a U-tube DPR-YWE model with a Y-mode oscillator with a PTE-98 excitation cell and a DPR-2000 electronic board by Anton Paar, Austria). A number of runs were repeated to check for reproducibility of the results. Four batch runs are described in Table I below and their conversion histories are plotted in Figure 1. 

In this paper, a means is demonstrated for experimentally determining the percent of monomer conversion at which soap micelles disappear from the system during emulsion polymerization. By applying the mathematics and latex particle surface area which a soap molecule will occupy, developed for the soap titration particle size measurement procedure, the average particle size of the finished latex can be calculated. In fact, under some circumstances It might even be feasible to adjust monomer content. 

During emulsion polymoization proccesses crosslinking can occur due to the presence of radicals and unsaturation in the polymer chain. Chain transfer agents are often used to decrease the level of crosslinking during polymerization. The gel content of a crosslinkable polymo is d ned as the fraction of material of infinite MM experimental criteria are usually more aibitraiy, and strongly depend on the experimental procedure. The same holds for the gel point, Le. the conversion at which the first insoluble polymer network makes its appearance. For example, in ABS gel content can be based on the toluene extraction of the soluble fraction of the polybutadioie. Hie insoluble residue is the gel fraction by definition. 

The core-shell particles were prepared by seeded semi-continuous emulsion polymerization under monomer-starved conditions. A detailed experimental procedure for similar latices is given by Winnik et al. [20] and Kruger et al. [21]. The seed was prepared by batch emulsion polymerization. After synthesizing the PBMA core a highly crosslinked PnBA-shell with MAA comonomer... 

The majority of publications deal with the application of catalytic chain transfer (GGT) in bulk or solution, but examples in the patent literature do apply GGT to emulsion and suspension. These patents report only limited data and full details of the experimental procedures are not revealed. Molecular weight data for the final products are given, but information on coagulation, conversion, and particle size are often not provided. The use of GoBF in MMA emulsion polymerization has been reported outside the patent literature but efficient CCT was not achieved, suggesting the process may be sensitive to at least some of the reaction components. 

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