Plane Lattice Structure in Amorphous Region of Cellulose Fibers

Abstract

When cellulose fibers are treated with conc. aqueous solutien of AcOK, washed with benzene and dried at 80 C, they give a new strong meridional diffractioh (I0) corresponding to (010) of cellulose I or cellulose II. However, 10 changes more and more into a new first layer diffraction with a spacing of 9.5A (11) with an increase in drying temperature. In addition, new equatorial diffractions appear at 160 C, though they are weak. The treatment with AcOK gives no change in the crystallinity of the Cellulose fibers, which indicates that the new diffractions are due to AcOK-cellulose addition product formed in the amorphous region of cellulose fibers.
It was found that the more perfect crystallite ofAcOK-cellulose was obtained by washing potassium-cellulose with acetic acid. Theunit cell is monoclinic with a=24.83A, b=10.32A (chain axis), c=8.83A and β=101.2 . Miller indices of I0 and I1 are (010) and (110), respectively. The intensity of Ii is extraordinary strong and depends on cellulose fibers used. This implies .that I1 results from both perfect crystallite and imperfect crystallite in amorphous region of fibers. It was calculated that the imperfect crystal structure giving only I1 in fact relative arrangement between (200) planes. This fact was confirmed by Fraunphfer optical diffraction photograms for the two-dimensional plane lattice models.
(200) plane of AcOK-cellulose corresponds to (101)plane of cellulose that shows sheet like unity during reactions of cellulose. Therefore, it is considered that the (200) plane lattice structure of AcOK-cellulose is based on, the (101) plane lattice structure of cellulose in amorphous region of fibers.
Intensity of I0 increases proportionaly with decrease of crystallinity of cellulose fibers used, It is believed that the (101) plane lattice structure, special type of crystal defect, is representative structure in amorphous region of cellulose fibers.