Chemical and Physical Properties of Cotton Modified by N-Methylol Agents
1984
Vail, Sidney L. | Zhou, Xiang
A study of the influence of cotton cellulose on reaction paths and rates involving intermediate oxonium-carbonium ions has been expanded to include a similar study of immonium-carbonium ions. A study of these mechanisms suggests that for acetal- or aldehyde-type reactions, cellulose can have an influence on reaction paths and rates, but for N-methylol-type reactions, cellulose would only be expected to have an influence on the rate. These generalizations depend on a number of factors and limitations which are discussed here for both the forward (cure) and reverse (recure or hydrolysis) reactions. Monomeric grafts or crosslinks to cellulose in the presence of formaldehyde crosslinks were found to be readily accessible to the hydrolytic medium. Considerations based on comparisons of the resistance to acid hydrolysis of cellulose ethers prepared from N-methylol methyl carbamate, its isopropoxy and acetoxy derivatives, and from N-methylolpyrrolidone suggest that these pure car bamates do not produce a pure finish. The finish from N-methylolpyrrolidone is considered to be pure and its formation in the presence of organic solvents and its resistance to hydrolysis were examined. Based on these studies the conclusion was that in comparisons of derivatives of cotton cellulose, chemical effects appear to determine completely the resistance to hydrolysis of a specific or pure finish. Further, leaving group effects from 2-, 3-, or 6-positions of cellulose play only a partial role, and cellulose appears also to influence the rates of reaction in a manner similar to the solvent in homogeneous reactions. Stronger or longer reaction conditions are needed for an agent to complete reaction because of a slower rate in certain portions of cotton cellulose during the cure. Links to cellulose formed in this manner produce a more durable finish. Generalizations made in this paper apply to conventional finishing and stripping conditions.
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