FINE-STRUCTURE AND TENSILE PROPERTIES OF RAMIE FIBERS IN THE CRYSTALLINE FORM OF CELLULOSE-I, CELLULOSE-II, CELLULOSE-III-I AND CELLULOSE-IV-I

This study focuses on the change in the fine structure and tensile pro perties of ramie fibres by the treatment for crystalline conversion. T hrough the conversion from cellulose I into II, IIII and IVI, the inte gral crystallinity index and the crystallite size decreased and the in ternal surface area increased while Young's modulus of the fibre decre ased and the ultimate strain increased. Two phase parallel, series and parallel-series models which comprise two kinds of springs with diffe rent constants representing the crystalline and amorphous components, respectively, were applied to the tensile force-strain relationship of the fibres. The parallel model could not be applied to the samples be cause the crystal lattice strains were smaller than the fibre strains; the former strains were less than one fourth of the latter ones, at a ny given tensile load. On the basis of the series model, Young's modul us of crystalline component of cellulose IIII was the highest and the next was that of cellulose I, followed by II and IVI. Young's modulus of amorphous component of cellulose I was the highest and the next was that of II, followed by IIII and IVI. Applying a parallel-series mode l, the values for Young's moduli of crystalline and amorphous componen ts were found to depend both on the feature of crystalline component a nd the density of amorphous region. Copyright (C) 1996 Elsevier Scienc e Ltd.