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 thermal decomposition of persulfate in aqueous solution in the presence of acrylonitrile (AN) monomer (M) and of nitrogen, may be written as: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{ - d\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)} \mathord{\left/ {\vphantom {{ - d\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)} {dt{\rm }\alpha }}} \right. \kern-\nulldelimiterspace} {dt{\rm }\alpha }}\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)^{1.35 \pm 0.05} \times \left( M \right)^{1.26 \pm 0.069} $$\end{document} in the concentration range of persulfate (1.8 to 18.0) ×10-3, and of monomer (M), 0.30 to 1.20, mol dm-3.It was observed that the pH of the solution containing persulfate and monomer did not alter during polymerization if the monomer concentrations were close to its solubility under the experimental conditions. Conductance of the aqueous solutions of persulfate and monomer was found to decrease during the reactions. In an unbuffered aqueous solution containing only persulfate, however, the pH was found to decrease continuously at 50°C with time, while the conductance of the solution was found to increase. The monomer (AN) had no effect on the glass electrodes of the pH meter in aqueous solutions, and also on the electrodes of the conductivity cell. It has been suggested that the secondary or induced decompositions of persulfate were due to the following elementary reactions: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\left( {\rm X} \right)} \hfill {\rm } {\rm S}_2 {\rm O}_8^{2 - } + M \to \cdot M \hbox{---} {\rm O} \hbox{---} {\rm SO}_3^ - + {\rm SO}_4^{ \cdot ^ - }, \hfill\\ \\ {\left( {\rm Y} \right)} \hfill {\rm } {\rm S}_2 {\rm O}_8^{2 - } + M_j^ \cdot \to M_j \hbox{---} {\rm O} \hbox{---} {\rm SO}_3^ - + {\rm SO}_4^{ \cdot ^ - }, \hfill \\ \\ \end{array} $$\end{document} where (Mj· radicals (j = 1 to 10) are water-soluble oligomeric or polymeric free radicals. kx and ky at 50°C have been estimated as 1.70 X 10-5 and 5.08 × 103 dm3 mol-1 s-1, respectively. By measuring pH of freshly prepared persulfate solutions at 25°C, it is suggested that 0.05-0.30% of persulfate reacts molecularly with water (i.e., hydrolysis), as soon as it (10-3 to 10-2 mol dm-3) is added to distilled water (pH 7.0). This hydrolysis was found to be stopped in dilute sulfuric acid solution (pH 3-4).
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1988.070350604
Permalink
