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Persulfate initiated aqueous polymerization of acrylonitrile at 50°C in an inert atmosphere of nitrogen gas
Author(s) -
Sarkar S.,
Adhikari M. S.,
Banerjee M.,
Konar R. S.
Publication year - 1988
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.1988.070360812
Subject(s) - potassium persulfate , aqueous solution , acrylonitrile , monomer , polymerization , chemistry , polymer , persulfate , polymer chemistry , ionic strength , colloid , inorganic chemistry , organic chemistry , copolymer , catalysis
The rate of aqueous polymerization ( R p ) of acrylonitrile (AN) initiated by potassium persulfate at 50°C, is given by:\documentclass{article}\pagestyle{empty}\begin{document}$$ R_p {\rm }\infty \left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)^{0.47 \pm 0.06} \times \left( {\rm M} \right)^{1.40 \pm 0.059}$$\end{document} where (M) stands for monomer concentrations. It has been suggested that persulfate ions in aqueous solution (pH 4 to 7) decompose not only via the well established paths viz.: (A) and (B) (A)\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}_{\rm 2} {\rm O}_8^{2 - } \to 2{\rm SO}_4^{. - } $$\end{document}(B)\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}_{\rm 2} {\rm O}_8^{2 - } + {\rm H}_2 {\rm O} \to {\rm HSO}_4^ - + {\rm OH} + {\rm OH} + {\rm SO}_{\rm 4}^{{\rm .} - } ,\left( {{\rm or }2{\rm HSO}_4^ - + \frac{1}{2}{\rm O}_{\rm 2} } \right) $$\end{document} but also via (C) and (D) in the presence of AN monomer: (C)\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}_{\rm 2} {\rm O}_8^{2 - } + {\rm M} \to {}^.{\rm M}\hbox{-\hskip-1pt-}{\rm O}\hbox{-\hskip-1pt-}{\rm SO}_3^ - + {\rm SO}_4^{. - } $$\end{document}(D)\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}_{\rm 2} {\rm O}_8^{2 - } + \left( {{\rm M}_j^. } \right)_w ,\left( {j = 1{\rm to }10} \right) \to {\rm M}_j\hbox{-\hskip-1pt-}{\rm O}\hbox{-\hskip-1pt-}{\rm SO}_3^ - + {\rm SO}_{\rm 4}^{{\rm . - }} $$\end{document} where (M ˙ j ) w is a water‐soluble monomeric/oligomeric free radical. The separating polymer phase remains in aqueous solution as a stable colloid, or a precipitate, depending on the ionic strength of the medium. At high conversions in general, and even at low conversions at relatively higher monomer concentrations, (1.20 m/dm 3 ), the colloidal latex polymer was found to have a tendency to form gel, and the viscosity of the medium was found to increase with conversions. The distribution coefficient of the monomer between the polymer and the aqueous phases was found to be (0.50 ± 0.10) at 50°C in the presence and absence of electrolytes (K 2 SO 4 7.5 × 10 −3 m/dm 3 ). The termination rate constants in the aqueous phase ( k tw ) and in the polymer phase ( k tp ) have been estimated as given below:\documentclass{article}\pagestyle{empty}\begin{document}$$ k_{tw} = 5.95 \times 10^{10} ;{\rm and }k_{tp} = 3.83 \times 10^7 ,{\rm in }{{{\rm dm}^3 } \mathord{\left/ {\vphantom {{{\rm dm}^3 } {{{\rm m} \mathord{\left/ {\vphantom {{\rm m} {{\rm s,}}}} \right. \kern-\nulldelimiterspace} {{\rm s, \right. \kern-\nulldelimiterspace} {{{\rm m} \mathord{\left/ {\vphantom {{\rm m} {{\rm s,}}}} \right. \kern-\nulldelimiterspace} {{\rm s,$$\end{document} taking k p of Dainton et al. as 6.22 × 0 4 (dm 3 /m/s) at 50°C.