The Strength and Weakness of Cotton Fibers

Abstract

The structural reversals in cotton fibers are a preferred location of break when the fiber is ruptured in tension. With the aid of a polarizing microscope, observations were made of the fraction of fibers breaking at the reversals under various conditions of moisture content, specimen length, and chemical treatment. It is concluded that the cellulose in the region of the reversals is more highly crystalline than the cellulose between the reversals. The cause for breakage at the reversals is then explained on the basis of internal stresses at these points which cause the fiber to tear apart when tension is applied. The weak places between reversals which give rise to fiber rupture are believed to be at structural defects or thin places. The mean breaking stresses for fibers breaking at the reversals vary significantly from those for fibers breaking between reversals for some varieties of cotton. The distributions of weak-spot location and strength for reversals and structural defects are discussed for three varieties.