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Continuous emulsion polymerization of vinyl chloride
Author(s) -
Berens A. R.
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070180816
Subject(s) - emulsion polymerization , vinyl chloride , residence time (fluid dynamics) , particle (ecology) , particle size , polymerization , polymer , particle size distribution , steady state (chemistry) , chemistry , continuous stirred tank reactor , continuous reactor , emulsion , thermodynamics , monomer , yield (engineering) , particle number , polymer chemistry , materials science , chemical engineering , organic chemistry , physics , copolymer , catalysis , oceanography , geotechnical engineering , engineering , geology , volume (thermodynamics)
For batch emulsion polymerizations of vinyl chloride, the reaction rate can be well represented by the empirical expression dx/dt = k (1 + ax ), where x is the polymer concentration, and k and a are constants dependent upon initiator concentration and particle number. A simple mathematical model for continuous stirred‐reactor polymerizations has been derived from this expression. The model predicts that at short residence times, a steady state of low PVC concentration is reached quickly; with longer residence time, the system more slowly approaches a higher steady‐state polymer concentration. Above a critical residence time, equal to 1/ak, the rate of monomer supply becomes the limiting factor. Experimental data on continuous polymerizations are in good qualitative accord with the predictions of the model using constants fitted to batch‐charge data. Quantitative agreement is best when the particle number is large; discrepancies may be attributed to a broader particle size distribution in continuous runs. Particle size measurements show evidence of intermittent particle formation in unseeded continuous runs; continuous seeding narrows the particle size distribution, but it is still broader than in batch charges. The model seems sufficiently valid to yield a number of useful implications about practical aspects of continuous emulsion PVC polymerization.