|French, Alfred - Al|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 11/9/2005
Publication Date: 6/16/2006
Citation: French, A.D., Johnson, G.P. 2006. Preliminary Modulus and Breakage Calculations on Cellulose Models. National Cotton Council Beltwide Cotton Conference. p. 2410-2417. Interpretive Summary: The Young’s Modulus (elasticity) strength are important practical properties of fibers. It is useful to know the theoretical maximum values of these properties so that quality of actual fibers can be assessed. Also, if the mechanisms of elasticity and breakage are to be studied by modeling, it is important to know that the modeling is accurate. Fibers that are primarily composed of cellulose, such as cotton, can be stretched with the computer analogously to stretching the actual fibers in laboratory testing devices. In this work a simplified model of cellulose was stretched in the computer. It gave a considerably lower value of the Young’s modulus by several methods. Further work is anticipated. This work is of interest to scientists studying the physical properties of fibers.
Technical Abstract: The Young’s modulus of polymers can be calculated by stretching molecular models with the computer. The molecule is stretched and the derivative of the changes in stored potential energy for several displacements, divided by the molecular cross-section area, is the stress. The modulus is the slope of the stress/strain line. The stress for cellulose has been calculated with empirical force fields a number of times, with different results. We have undertaken such calculations on a simple model of cellulose based on tetrahydropyran rings. We used both empirical methods and electronic structure theory, also called quantum mechanics, the latter of which can be carried to the point of rupture of the model molecule. By starting with a simplified model, we are attempting to increase the understanding of the molecular bases for modulus and tenacity and the roles that water plays therein. This presents our preliminary results.