Deformation processes in regenerated cellulose fibers

Molecular deformation processes of regenerated cellulose fibers are investi gated using Raman spectroscopy. These fibers have well-defined Raman spectr a, and the main Raman bands in tho region of 895 to 1170 cm(-1) shift to lo wer wavenumbers upon application of tensile strain and stress. The peak pos itions of the Raman bands at 895 and 1095 cm(-1) show an approximately line ar relationship with strain and stress. For fibers with lower moduli and mo re nonlinearity in their stress-strain curves, there is poorer correlation with strain and stress, consistent with mechanical data and structural char acteristics. Also, the strain sensitivity of the Raman band strain shift (i n cm(-1)/%) increases with the Young's modulus of regenerated cellulose fib ers, and there is a universal stress band shift of about -4 cm(-1)/GPa for both bands, consistent with a modified series model of deformation. Deviati ons from this model for lower fiber moduli are discussed with evidence to s uggest that chain slippage and re-orientation behavior dominate.