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Effect of pH Value on the aqueous precipitation copolymerization of acrylonitrile and vinyl acetate
Author(s) -
Yao Zhen,
Chen HuanJin,
Qin YiXiu,
Cao Kun
Publication year - 2010
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.32778
Subject(s) - vinyl acetate , acrylonitrile , copolymer , chemistry , particle size , aqueous solution , polymer chemistry , monomer , particle (ecology) , radical polymerization , chemical engineering , polymer , organic chemistry , oceanography , engineering , geology
The aqueous precipitation copolymerization of acrylonitrile (AN) and vinyl acetate (VAc) with NaClO 3 /NaHSO 3 redox initiation system is carried out continuously in a 10L pilot‐plant reactor. The effects of pH value on ionization equilibrium of NaHSO 3 , polymerization rate, particle morphology, particle size and its distribution, molecular weight and its distribution have been investigated. It has been found that effective concentration of reductant H 2 SO 3 increases with the decrease in pH value. On the other hand, deceasing pH value intensifies the coalescence among particles and then reduces diffusion rate of monomer and radicals into particles. Experimental data shows that the increase of pH value results in higher conversion. It indicates that pH value's effect on particle stability prevails its influence on effective concentration of the reductant. This conclusion is verified by the molecular weight, particle size, and particle morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011