A study of X‐ray orientation in never‐dried cotton fibers

Abstract

Investigations in the recent past have led to the opinion that the spiral angle of fibrils in different genetic varieties of cotton is more or less the same and that the differences found in X-ray orientation angle measured on fiber bundles are due largely to the influence of convolutions formed during the initial desiccation of fibers in the cotton bolls. It was Meredith,1,2 who observed for the first time that the spiral angle deduced from refractive indices is nearly the same (ca. 21") for all varieties of cotton when the effect of convolutions is corrected for. An extension of this work by Betrabet et al.3 to Indian cottons also led to the same conclusion.More recently, Hebert4 measured the spiral angle by Hakshorne's optical method6 and confirmed the earlier observation that spiral angle of cotton is a constant at around 21". Duckett and Tripp6 using a single-fiber X-ray technique showed that the variation in spiral angle among different varieties is small. Morosoff and Ingram7 examined the interconvolution tracts by X-ray diffraction as well as by Hartshorne's method and found that the spiral angle is a constant in the range 20-23". De Luca and Orr? on the other hand, have reported a range of values for the sprial angle (12-18") among different varieties on the basis of a modified Xray method.One thing common to all earlier investigations on the true spiral angle of cotton discussed above has been the use of naturally dried, convoluted fibers for the measurement.

True spiral angle in cotton of gossypium arboreum

“…Further, the average angle of orientation (a,) measures the true spirality in cotton more faithfully than do the arbitrary 40 or 50% X-ray angles. This is evident from the correlations of true spiral angle deduced from (am) with bundle tenacity and with other orientation parameters 1.000…”

The correlation between X‐ray orientation parameters and strength of fibers in native cotton

“…26 Both 40 and 50% X-ray angles and a, have been widely used as measures of ~p i r a l i t y~,~' ,~~ to correlate with fiber properties, but with varying success. Therefore, following the above reasoning, 26 at least three different close measures of true spiral angle can be obtained by substracting the values of the convolution angle from the values of a, and 40 and 50% X-ray angles. The close values of true spiral angles so obtained for 23 of the 24 cotton varieties are presented in columns 6a, b, and c of Table I, respectively.…”

“…The true spiral angles in never-dried cotton have also been calculated in this way previously. 26 Both 40 and 50% X-ray angles and a, have been widely used as measures of ~p i r a l i t y~,~' ,~~ to correlate with fiber properties, but with varying success. Therefore, following the above reasoning, 26 at least three different close measures of true spiral angle can be obtained by substracting the values of the convolution angle from the values of a, and 40 and 50% X-ray angles.…”

True‐spiral angles in diploid and tetraploid native cotton fibers grown at different locations

“…Three different close measures of the true spiral angles were computed in respect to the cotton varieties studied, following the logic of Iyer et al 42 by subtracting the values of the convolution angle () from the values of the 40 and 50% X-ray angles and the average angle of orientation (␣ m ) as suggested earlier by Moharir 43 and Moharir et al 44,45 The data on the three close measures of the true-spiral angles are given in Table I. In Table II are given the locationwise average values of the true-spiral angles for individual cotton va-rieties for all crop years and replications.…”

“…However, since the X-ray angle is closely related to the angle of spirality (() and the values of the two are numerically very close, the subtraction of the convolution angle () from the X-ray angles would also yield a close measure of the true-spiral angle. This argument has been previously used to calculate true-spiral angles in solvent-exchanged never-dried cotton by Iyer et al 42 Moharir 43 and Moharir et al 44,45 proposed and used this argument in calculating at least three different close measures of the true-spiral angle in Gossypium hirsutum and Gossypium arboreum cotton. Also, while doing so, they emphatically determined the choice of the average angle of orientation (␣ m ) derived from the Hermans crystallite orientation factor (f) to be the best index of spirality for computing the true-spiral angle in cotton.…”