A Quantitative Picture of the Fringed Micellar Model of Cellulose

Abstract

Quantitative diagrams of the fringed micellar model have been produced for tire cord, Fortisan, wood cellulose, cotton, ramie and bacterial cellulose, based on the results of the reactivities of these celluloses towards deuterium oxide and acid hydrolysis. The hypothesis has been used that rapid acid hydrolysis occurs in the truly amorphous zones, whereas deuteration occurs not only in these zones but also on the surfaces of the crystallites. It is from this hypothesis that calculations of crystallinity, crystallite width, and crystallite length have been made. The calculated fractional crystallinities of native celluloses are, therefore, in the range of 0.89-0.96, while those of regenerated celluloses range from 0.65 to 0.85. These crystallinities are higher than previously accepted values and are more in keeping with the most recent interpretation of x-ray diffraction patterns. The values of calculated crystallite width were about 17Å for the regenerated celluloses and 32Å for native celluloses. The latter value is close to that currently proposed by electron microscopists. Crystallite lengths were calculated from the levelling-off DP found on acid hydrolysis. The various methods of measuring crystallinity are discussed in terms of the model, as are microfibrils, crystallites, and paracrystalline cellulose.