Abstract


2- Molecular structure of cellulose-I

Cellulose is a polymer of D-glucopyranose in which pyranose rings are linked by

V- Conclusion

We have carried out Wide Angle X-ray Scattering profile analysis of Jayadhar cotton fiber and we have computed the unit cell and microstructural parameters of this fiber by using Line Profile Analysis for X-ray diffraction based on the Warren's Fourier single order method, developed by us. These computations indicate that the strains are small and Jayadhar cotton fiber has different values of crystallite size components in different directions. The reason being the binding force between molecules (atoms) of cellulose arising due to inter-, intra- hydrogen bonds and covalent bonds. Our study on cotton Jayadhar fibers has provided the very small structural changes when corrected for intrinsic strains present in the raw fibers. Based on a model wherein two chains in a unit cell are parallel[19] with the same conformations with refinement against the X-ray fiber diffraction data, gives a reasonable good fit (R=17 %). Earlier values of R factor by Hunter and Dweltz[16] of Jones were 49% and 50% respectively. We have examined and quantified the disorder present in the material using Line Profile Analysis using well-established method. Most of the broadly of the reflections observed in cotton fibers is due to smallest crystallite size of the order of 50, and not due to the intrinsic strain present in the cotton fibers, which, indeed, clear the misconception that there is disorder along the fiber axis. The only plus point for correcting the intrinsic strains in that it reduces the stereo-chemical energy leading to a more stable structure given here. In a unit cell, the position of the C ═ O group of chain along c-axis is oriented in one direction at one position and in opposite direction in another position. Such an arrangement results in a dipole, which stabilizes the crystal lattice of Jayadhar cotton fibers in this study.


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Table 1 Microstructural parameters of Jaydhar cotton fiber by using Exponential distribution function of crystal size.


Table 2 Final model parameters of Cellulose for both structures after several refinements using LALS software for experimental intensities.