Structural Properties of Cotton Fibers: Part II: Birefringence and Structural Reversals in Relation to Mechanical Properties

Abstract

Birefringence and structural reversals have been determined on 20 Indian cottons and correlated with their mechanical properties. The variation in spiral angles among cottons is influenced by the variation in convolution angle, and Meredith's observation that average spiral angle in the original unconvoluted fibers may be the same for all the varieties is supported by the results obtained. Specieswise distribution of structural reversals was determined by a simple, quick method. Deshi2 cottons have very few reversals as against cottons belonging to the G. hirsutum and G. barbadense species. Hence, the distribution of reversals appears to be a genetic characteristic and it would be worth investigating whether Wakeham and Spicer's observation of preferential breakage at points of reversals holds good for deshi cottons. The average distance between reversals is found to be highly correlated with the cotangent of the spiral angle at constant cell width just as in the case of wood tracheids and bamboo fibers, observed by Meredith; the peculiar behavior of G. arboreum indicum cottons in this regard has been pointed out. The manner in which the varieties of cottons selected for investigation influence the trend of the results is indicated.