| Abstract: | Experimental data are presented showing the effect of reactor agitation intensity and reactor size on final resin properties during VCM suspension polymerization. Experiments were carried out in three stirred batch polymerization reactors covering a broad range of vessel sizes (bench scale, pilot plant, and commercial production units). Reactors' shapes were geometrically similar. The same charge recipe and operating procedure was also used for all three reactors. The effects of major agitation parameters such as impeller diameter, width, and speed are correlated against resin properties using the Weber number. The same characteristic U-shaped curve is found for all three reactors when mean particle diameter is plotted versus Weber number. However, the curves do not lie on top of one another but are spread apart, the larger reactors having a higher Weber number. Another interesting feature is that the coefficient of variation (particle size standard deviation divided by mean diameter) decreases dramatically as reactor size is increased. Other resin properties also show improvement upon scale-up. In summary, resin properties continue to improve as reactor size is increased over the range studied (bench-to-commercial large reactor scale), but a correct application of the complex scale-up technology must be employed to take advantage of this observation. |
