No abstract

The elongation at break äs well äs the tensile modulus of solvent spun cellulose fibres, both measured in the conditioned state, correlate with the amorphous orientation factor. The relevant regression curves are similar to that of the relation between the elongation at break resp. the tensile modulus and the crystallite orientation factor; the latter preceding the amorphous orientation factor with increasing total orientation. Hence it is concluded, that the elongation mechanism of regenerated cellulose fibre does not consist only of orientation of crystallites, but that additionally a straightening and orientation of the less ordered molecular segments in the interstices between the crystallites has to be assumed.

The evaluation of the long periods and crystallite lengths of original and pretreated solvent spun cellulose fibres revealed that thcy consist of about YOO/ocrystalline cellulose in the direction ofthe fibre axis. In the case of high wet modulus viscose fibres this percentage is only 50-60%. The intensity of the long period of solvent spun fibres is lower than that of the high wet modulus viscose fibres corresponding to a smaller difference between their crystalline and amorphous orientation factors. There is existing a significant correlation between this difference and the intensity of the long period.Verglrichende Charakterisierutig von losungsersponnenen Celluloseund hochnaflfesren Viskosefasern durch ihre La n,yp cri o deti Die Auswertung der Langperioden und Kristallitlangen originaler sowie vorbehandelter, losungsersponnener Cellulosefascrn ergab. dal3 diese in Richtung der Faserachse zu ca. 90O/oaus kristalliner Cellulose bestehen. Bei hochnaBfesten Viskosefasern betragt dieser Anteil nur 50-60 %. Die Intensitat der Langperiode der losungsersponnenen Fasern ist niedriger als die der hochnaRfesten Viskosefasern entsprechend einer geringeren Differenz zwischen ihrem kristallinen und amorphen Orientierungsfaktor. Zwischen dieser Differenz und der Langperioden-Intensitat besteht eine signifikante Korrelation.

SynopsisThe development of new methods of spinning cellulosic fibers requires a better understanding of their fibrillar structure in order to explain their special physical properties. By means of transmission electron microscopy (TEM), light microscopy (LM), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD) it is shown that six different kinds of regenerated cellulosic fibers consist of uniform elementary fibrils composed of cellulose-I1 crystals. Systematic distinctions between these fiber types are found with regard to the aggregation of the elementary fibrils to nonswelling bundles or clusters. The clusters differ from each other in diameter, length, and frequency of occurrence.

The layered structure in 2 mm thick discs injection moulded from industrial polypropylene (PP) was studied by scanning the cross section of the mouldings by means of small-and wide-angle X-ray scattering (SAXS and WAXS), using a Kratky collimation system for position-resolved quantitative scattering measurements in both angular domains. The registration of so-called scattering profiles of the mouldings and a texture analysis of the WAXS profiles were established as novel approaches for studying the cross-section architecture. The results of the investigations comprise statements on the preferential orientation and the local distribution of a-and fl-PP in different layers of the cross sections, on crystallite sizes and on the behaviour of individual layers in tensile tests.