The supermolecular structure and morphology of extruded flat films from several native starch materials of A an B crystal type were investigated by wide-angle X-ray scattering and scanning electron microcopy. The degree of crystallinity and crystallite dimensions of both the different starting materials and the extruded films were determined and a scheme of the lattice transformations resulting from extrusion was established. The conditions of structure formation of the extruded starch films were varied in relation to plasticizer composition and extruder zone temperatures. The mechanical properties and biodegradability of the films were also measured. The extruded starches crystallized in the V-H polymorph with crystallinities between 33 and 41% and crystallite sizes of up to 35 nm. An increase in crystallite size was found for all starches (sometimes a doubling) with increasing extruder middle zone temperatures from 120 up to 210 degreesC. For extruded potato and maize starches a steep rise in strength and modulus and a drop in elongation was observed about 190 degreesC. Purified amylopectin from maize showed after extrusion the crystalline A-type and small amounts of B polymorph with small crystallites (up to 3 nm) and the best mechanical performance with strengths and moduli of about 20 MPa and 1500 MPa, respectively, for the present extrusion conditions. Native starch films that include 20 to 30% plasticizer biodegrade rapidly in 25 d consuming 90% of the oxygen needed for complete degradation, as analyzed by the Sapromat test.

Separated amyloses with different molecular weight distributions were obtained enzymatically from wrinkled pea starch and processed in a multi-zone twin-screw extruder. The crystalline polymorphs, crystallinity and crystallite dimensions of amylose (unbranched molecular starch component) and films extruded from it were investigated by wide-angle X-ray scattering. The starting amylose materials exhibit a crystalline VA structure with rather large crystallites (9–25 nm) and a degree of crystallinity ranging between 30 and 40%, depending on the history of the amylose sample. The extruded films, on the other hand, recrystallized in the B-type with a slightly higher degree of crystallinity and significantly smaller crystallite dimensions (3–7 nm). In one case, VH-type crystals were observed. The mechanical properties of the extruded materials were determined in tensile tests. The amylose with the highest molar mass produces films with the highest mechanical performance. As compared with cellulose or synthetic polymer films, the mechanical properties of the amylose films appear to be fundamentally limited by the lack of preferred molecular orientation.

The supermolecular structure of the cellulose in flax, hemp, jute, ramie, and cotton was investigated by wide angle Xray scattering and C-13-CP/MAS-NMR-spectroscopy. It was found that the crystalline regions of the bast fibres flax, hemp, and jute represent a mixture of approximately 50% l(alpha) and l(beta) cellulose, exceeding the la portion of ramie and cotton linters by 10% to 20%. The cellulose related crystallinity of flax, hemp, and jute was found to be between 55% and 60% thus being only slightly smaller than the crystallinity of linters. The lateral crystallite dimensions of all the investigated bast fibres are in the same: range (depending on the direction 3 nm to 5 nm), however, larger differences were obtained with regard to the longitudinal crystallite dimensions (20 nm- 29 nm). The orientation of the fibres was characterized by the Hermans-factor and the average spiral angle of the cellulose fibrils. The spiral angles of flax and hemp are very similar (appr. 4 degrees) and smaller as compared with jute (5 degrees). Effects of mercerization on the structure and properties of bast fibres were studied with hemp yarn as an example. The influence of NaOH concentration, temperature, duration of the mercerization, pretreatments of the fibres, and of the strain applied to the fibres was investigated and judged via the cellulose I - II lattice transition. It was shown that by using appropriate mercerization parameters the mechanical properties of hemp can be controlled in a broad range.

The course of the lattice transition of cellulose by interaction with aqueous and aqueous-ethanolic solutions of NaOH was studied using two methods. First, the conversion reaction was stopped by adding acetic acid and subsequent determination of the amount of cellulose II by a conventional WAXS technique. Second the change of the crystalline lattice was recorded n situ by a series of WAXS-patterns obtained by synchrotron radiation with a time resolution of 15s. With an aqueous lye of 12 to 18% NaOH concentration, the lattice transition is completed in less than 15s. An increasing part of ethanol in the reaction system, however, reduces the rate of transition drastically. Lattice transition due to alkalization was approached kinetically y by a second order law, rate constants for aqueous NaOH solutions were obtained by extrapolation. Causes for the different behaviour of water and ethanol are discussed.

The course of the lattice transition of cellulose by interaction with aqueous and aqueous-ethanolic solutions of NaOH was studied using two methods. First, the conversion reaction was stopped by adding acetic acid and subsequent determination of the amount ol cellulose II by a conventional WAXS technique. Second, the change of the crystalline lattice was recorded in situ by a series of WAXS-patterns obtained by synchrotron radiation with a time resolution of 15 s. With an aqueous lye of 12 to 18% NaOH concentration, the lattice transition is completed in less than 15 s. An increasing part of ethanol in the reaction system, however, reduces the rate of transition drastically Lattice transition due to alkalization was approached kinetically by a second order law, rate constants for aqueous NaOH solutions were obtained by extrapolation. Causes for the different behaviour of water and ethanol are discussed.

Microstructural investigations of surface-grown and surface-grown/zone-drawn ultra-high molecular weight polyethylene (UHMWPE) fibers were carried out by scanning- and transmission-electron microscopy (SEM, TEM), by optical diffraction (OD) of the TEM images, and by small angle X-ray scattering (SAXS). The as-spun filaments show a “shish kebab” morphology characterized by a periodic arrangement of the overgrowths. During zone-drawing the shish kebabs are transformed into well-aligned needle crystals. At medium-draw ratios this is accompanied by considerable improvement of the mechanical properties, whereas draw-ratios exceeding approximately 2.5 lead to a reduction in strength and modulus due to “overdrawing” effects.

Wide and small angle X-ray scattering experiments have been performed with synchrotron and conventional radiation in order to investigate the structure formation process during spinning of cellulose fibres from NMMNO solutions. It is found that in the never dried fibre, the three-dimensional order is not fully developed, although chain orientation is fixed to a large degree. Crystallite orientation can be improved by increasing the length to diameter ratio of the spinning nozzle and by increasing the take-up speed, although here a levelling off is shown. SAXS reveals maximum lateral structural dimensions of 15 and 26 nm for the wet and dry fibres, respectively, an increase explained by clustering of fibrils (and bundles) to larger bundles. Structure and properties of the final fibres can be varied by appropriate drying conditions and post-treatments of the never-dried fibres to hamper crystallization, e.g. with ethanolic NaOH.

A survey of X-ray diffraction methods is given including phase analysis, determination of crystallinity, crystallite dimensions, lattice distortions, fibre orientation factors, as well as noncrystalline order and pore structure characterization. Comparative structural investigations on dissolving pulps obtained from conventional and new processes are presented, structural changes due to grinding are shown. Alkali celluloses from steeping lyes concentrated up to 50% NaOH were investigated as a reference for assessing the effect of alkalizing alcoholic systems also demonstrating the role of cellulose supramolecular structure in the alkalization process. At last, possibilities oi X-ray characterization of cellulosic man-made fibres as a final product are presented.

In carbon fibre processing, poly(acrylonitrile) filaments are stabilized by heat treatment giving rise to complex physical and chemical structure transitions of the precursor material. The combined application of DSC and shrinkage force measurements, IR and 13 C-CP/MAS-NMR spectroscopy, as well as wide and small angle X-ray scattering is useful to elucidate the various structural transitions and therefore to optimize the stabilization process.

The thermal oxidative stabilization of PAN fibres was investigated by small and wide angle X-ray scattering and by measurements of the fibre density. It has been proved that stabilization starts in the less ordered regions and proceeds to higher ordered domains. Dimensions of these regions were estimated.

The supermolecular structures of polyethylene filaments prepared by crystallization from solution in extensional flow at different crystallization temperatures as well as of annealed and zone-drawn samples have been characterized by means of X-ray diffraction methods. The lattice distortions in the crystallites of such samples are quantitatively determined for the first time. The results show that a direct correlation between the crystallite dimensions and the amount of lattice distortions on the one hand and the axial Young's modulus on the other hand can be excluded. Based on X-ray, mechanical and shrinkage investigations, some parameters of the structure of the non-crystalline regions are estimated. A structure model for the high-modulus polyethylene filaments is discussed.

Combined applications of IR and NMR spectroscopy, small- and wide-angle X-ray scattering, and electron microscopic methods on specific examples of solid polymers are demonstrated. Recent results are presented for PE structures including high strength/high modulus fibres, for the structural explanation of PVDF polarization effects, and for cellulose structure transitions related to alkali treatments. The key position of IR spectroscopy in analysing chemical structures is proved with additional examples.