Synopsis
Measurenients of the degree of orientation in cellulose filaments prepared from fractions of secondary cellulose acetate having a very limited range of degree of polymerization have shown that the degree of orientation produced by a given effective stretch increases aa the degree of polymerization increases. The orientation distributions of the (101) and (020) planes have been compared with those predicted by Kratky's theory for the deformation of a material containing rod-shaped crystallites, and i t has been shown that the shapes of the observed and theoretical distributions are the same if the appropriate value of the degree of stretch is used. This value is always less than that calculated from the changes in the dimensions of the filaments produced by stretching. Kratky's theorv cannot however account for the variation with degree of polymerization and does not account for the observed shape of the curves for orientation as a function of stretch. Consideration of the process by which the filaments were produced shows that the filaments were subjected to stretches additional to those intentionally applied to them. The results of the orientation measurements are compared with published figures for the birefringence and tenacity of similar filaments, and linear relations are found between birefringence and orientation and between tenacity and orientation.
* Parts of the content of this paper form the subject matter of a thesis by K. C. Ellis that has been approved by the University of London for the award of the Ph.D. degree.