Wax Content as Related to Surface Area of Cotton Fibers

Abstract

Among a group of 62 essentially unweathered fiber samples from American upland cotton plants of different inherent and environmental background, percent wax was found to be rather closely proportional to surface area per unit weight of fiber as determined by the air-flow method of Sullivan and Hertel [22]. The weight of wax per unit of fiber surface was thus a relatively constant quantity, although not an absolutely constant one, among these samples. Results of melting-point determinations did not suggest the probability of important qualitative differences in wax composition at the time of boll opening among the several American upland cottons studied, the sole exception encountered being the high-melting-point wax from the green-lint high-wax cotton previously reported by Conrad [6]. In a group of twelve Sea Island hybrids, both the amount of wax per unit fiber surface and the wax melting points were similar to the results obtained for American upland types. Five Indian cottons all had very low wax percentages; their surface areas were below the normal range of the method for surface-area determination. Weathering of cotton in the field before harvest resulted in higher wax contents as measured by the Conrad [7] method and lower wax melting points than were found for similar but un weathered samples. Further work is required to indicate the nature of the causal factors in volved in this change which occurs during weathering.