Effect of Maturity Ratio and Chemical Treatment on the Optical Orientation of Cotton Fibers

Abstract

The optical properties of two varieties of G. hirsutum of cotton fibers were studied at different
stages of maturity. A four- hour treatment of cotton in liquid ammonia at -50^oC ensures complete
change of the lattice structure from Cellulose I to cellulose III. The cellulose 1 lattice is restored
by boiling in distilled water for 24 hours. X- ray diffractograms confirms this. Mature fibers are
devoid of convolutions, rounded in appearance and completely devoid of the inner lumen. The
scanning electron micrographs revealed this. Molecular orientation measurements from both the
‘Becke line’ method and helix Angle calculation are strongly dependent on fiber maturity. This
shows that the ‘Backe line’ method does not measure only the birefringence of the fiber surface as
previously suggested. This, therefore, calls for a fresh look into the theoretical depth of this
technique. Mature regenerated fibers (after boiling) showed lower birefringence values than the
untreated fibers. This was attributed to the 2 % longitudinal shrinkage recorded during boiling
rather than the effect of convolutions. Environmental condition does have effect on the helical
angles of fibers