Elastic stiffness of crystalline cellulose in the folded-chain solid state

In previous papers the axial stiffness of crystalline native cellulose has been calculated for two proposed configurations of the cellulose chains within the elementary fibrils: an extended chain configuration, and a configuration in which the chains are folded to form a ribbon which in turn is helically wound into a rather open, spring-like structure. In the present paper two additional folded-chain configurations are treated: a more tightly wound helical configuration in which axial secondary bonds are formed between adjacent turns of the helix; and a configuration in which the chains are folded rather infrequently and remain in a fully-dense close-packed arrangement. It is shown that this last configuration is mechanically equivalent to the extended chain configuration so far as axial stiffness is concerned, and that either helical configuration has a substantially lower axial stiffness than that of the extended chain.The investigation reported in this paper (No. 69-8-64) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director.