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 light-induced degradation of aqueous hydroxypropylmethylcellulose (HPMC; D.S. 1.9) solutions has been investigated under a variety of conditions. The HPMC was sensitized to short-wavelength radiation (〈500 nm) by the addition of sodium nitrite, the degradation being accompanied by increased acidity and the generation of oxides of nitrogen. Addition of eosin dye increased the sensitivity to visible light (〉500 nm), and the effect was considerably more pronounced when strong electron donors were added. Analysis of the shear-viscosity relationship of the solutions, during the degradation, indicated that both chain disentanglement and chain scission occurred but that the primary process was the depolymerization of the cellulose chain. It is proposed that both the dye- and nitrite-induced depolymerizations are a consequence of peroxide attack on the β-glucosidic ether link. The results indicate that, in the case of sodium nitrite addition, the peroxide was generated by the aqueous photolytic decomposition of the nitrite ion. The peroxide formation in the eosin - TEA system was a consequence of leuco-dye production, under the influence of the light, followed by the reduction of traces of dissolved oxygen by this activated dye.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1972.070161002
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