The Modification of Cellulose by Reaction with Formaldehyde

Abstract

Experiments relating to the chemistry of the technologically important cellulose-formalde hyde reaction are described. While for many reasons definitive statements about the reaction cannot now be given, certain of its gross features are revealed. As the formalization process is usually carried out, the reaction with cellulose is com petitive with the evaporation of the formaldehyde. At low temperatures (to 30°C) no reaction takes place. At higher temperatures (150°C) reaction takes place over a wide range of con ditions of acidity. The product formed at high acidity is stable to hydrolysis and is charac terized by reduced swelling, increased elastic modulus, and resistance to creep. At lower acidities and under alkaline conditions, the properties of the product are much more like those of the starting material and the formaldehyde is easily removed by washing in neutral aqueous solutions. The combining weight of formaldehyde with cellulose varies, among other things, with the concentration of the formaldehyde applied. The lower the concentration the more nearly the combining weight approaches 12, which corresponds to the formation of simple methylene ethers with the cellulose. At higher concentrations, the combining weight increases toward a value of 30, indicating the formation of polyoxymethylene ether linkages.