ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The rate of aqueous polymerization (Rp) 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/dm3), 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 (K2SO4 7.5 × 10-3 m/dm3). The termination rate constants in the aqueous phase (ktw) and in the polymer phase (ktp) 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 kp of Dainton et al. as 6.22 × 04 (dm3/m/s) at 50°C.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1988.070360812
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