Reaction Vessels for Polymerization Reactions

Numerous special experimental arrangements that are suitable for particular monomers and types of polymerization are described in the literature, but they may all be regarded as modifications of the equipment described below. 

For reactions in which only a slight pressure rise is expected (e.g., emulsion polymerization of gaseous monomers), thick-walled pressure bottles which are carefully placed behind a protective shield, can be used. For higher pressures or large-scale experiments, autoclaves are always to be preferred. 

In (living) anionic polymerizations (e.g., Example 3-19) in the laboratory, a vacuum line is often employed all operations are then conducted under the same, rather high vacuum. Thus, optimum polymer yield and uniformity are secured. 

For kinetic investigations of homogeneous polymerizations, a variety of methods and apparatus has been developed. The dilatometric method is especially worthy of mention on account of its simplicity and general applicability (Fig. 2.3). 

This procedure is based on the measurement of the contraction of volume that results from the different densities of the monomer and polymer. The conversion of the volume contraction to the yield of polymer can be made by means of a gravimetrically determined calibration curve or by calculation from the specific volumes (see Example 3-6). 

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