Preliminary examination of the effects of relative humidity on the fracture morphology of cotton flat bundles

Abstract

A preliminary examination of the effects of relative humidity (RH) of three testing conditions on cotton fiber fracture morphology is presented herein. In addition, measurements of fiber moisture content, stelometer cotton flat bundle strength and elongation were collected at the three testing conditions. A general trend is observed for moisture content, strength and elongations measurements; testing in conditions with higher RH generally resulted in a progressive increase in moisture content, strength and elongation values. The morphology of broken fibers was also affected by the testing conditions. Fibers broken at high RH (i.e. 70 ± 2°F and 80 ± 2% RH) showed a more frayed fracture where microfibril separation, a fracture pattern that suggests independent microfibril failure, was evident. In contrast, at standard conditions (i.e. 70 ± 2°F and 65 ± 2%), fiber fractures were more granular (clean fractures), a reflection of a more unilateral breaking action. At low RH (i.e. 70 ± 2°F and 50 ± 2%), fiber fractures exhibited a distorted granular pattern, with extended fracture breaks that did not exhibit microfibril separation. Our preliminary findings are of relevance to post-harvest moisture control efforts currently employed in industry and may contribute to larger efforts to understand the effects of the fracture and damage observed in cotton fiber properties.