Under certain conditions high strength cellulose fibres can replace glass fibres as reinforcing materials for polypropylene. They have weight, abrasiveness, recyclability and disposal advantages.

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.

Cellulose as the most abundant regrowing organic material exhibits outstanding properties and useful applications, but also a tremendous challenge with regard to an economical and environmentally friendly chemical processing. In recent years the N-methylmorpholine-N-oxide (NMMO)-technology turned out to be a simple physical alternative to the yet dominating viscose-technology for producing regenerated cellulosic fibers, films, food casings, membranes, sponges, beads, and others without hazardous byproducts. With consideration of own results, the present paper reviews the state of the art knowledge on structure formation of fibers and films via the NMMO-route comprising the cellulose–NMMO–water phase system, the state of solution, the dry jet-wet shaping, the precipitation, and the drying stages. Dissolving pulp as the starting material can be dissolved easily without pretreatment in NMMO-monohydrate. The fairly (8–12%) concentrated solution of cellulose in NMMO-monohydrate is characterized by a marked elastic behavior similar to a polymer melt which can be quantified by rheological measurements of the storage and loss moduli. As found by light scattering experiments of diluted cellulose–NMMO solutions, there exist aggregates of molecules even in the diluted solution, with the number of molecules corresponding to solid state morphological units (crystallites, microfibrils). As shown by WAXS-RDF analysis of the concentrated solutions at elevated temperature, the typical short-range order of a pure NMMO–water system is only slightly disturbed by the cellulose molecules. Fiber formation occurs in a dry jet-wet spinning process, with several physical factors (e.g. nozzle and air-gap dimensions, draw-down ratio, take-up speed) and dope characteristics (cellulose DP and concentration, temperature, modifiers) influencing the shaping process and the final fibers properties. The precipitation process has been shown to be another stage capable to affect the structure and properties of the fibers as, e.g. by a two-step precipitation leading to a skin–core structure and improved fiber properties (reduced fibrillation). The NMMO method offers for the first time the possibility to produce blow-extruded tube-like films similar to the polyolefine blown film processing. The influencing parameters are discussed and the properties of the new blown cellulosic films are shown to be superior to cellophane. Finally, the structures and properties of the NMMO-type fibers and films have been investigated and differences between the new materials and the traditional viscose based fibers and films were shown and related to the different structure formation routes.

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.

After installing a C-GC-IRMS-System (Elemental analyzer EA 1108 CHN + IRMS MAT 252) some problems arose with respect to the external precision of the delta(15)N values (standard deviation approx. 1 parts per thousand at > 50 mu g N) after changeover from C-13 to N-15 measurements.Attempts were made to determine the reasons for these effects and to eliminate them by changes of the Carlo Erba on-line combustion system (EA) and the split.Non-quantifiable contributions, e.g., air nitrogen and/or N-2 in carrier gas helium were reduced by a blank correction.Using Cyclohexanone-2,4-dinitrophenylhydrazone it was shown that under the same conditions and after a com,non blank correction with small and large amounts of samples (60-650 mu g, 20% N) an external precision of 0.2%parts per thousand (standard deviation, 10 cycles) can be reached.

After installing a C-GC-IRMS-System (Elemental analyzer EA 1108 CHN + IRMS MAT 252) some problems arose with respect to the external precision of the δ15N values (standard deviation approx. 1‰ at < 50 μg N) after changeover from 13C to 15N measurements. Attempts were made to determine the reasons for these effects and to eliminate them by changes of the Carlo Erba on-line combustion system (EA) and the split. Non-quantifiable contributions, e.g., air nitrogen and/or N2 in carrier gas helium were reduced by a blank correction. Using Cyclohexanone-2, 4-dinitrophenylhydrazone it was shown that under the same conditions and after a common blank correction with small and large amounts of samples (60-650 μg, 20% N) an external precision of 0.2‰ (standard deviation, 10 cycles) can be reached.

The influence of annealing on the supermolecular structure of commercial, thermostable fibers, spun from solutions of poly(p-phenylene-1,3,4-oxadiazole) (POD) in H2SO4, is examined. The crystalline alpha-modification of thermally treated POD fibers has an orthorhombic unit-cell probably of space group P2(1)2(1)2(1). The symmetry of the single POD chain in these crystallites is 2(1). The unit-cell dimensions are a = 1.235 nm, b = 0.655 nm, c = 1.40 ... 1.47 nm, where c depends on the annealing temperature T(a). The unit cell contains 4 chains of two monomers each. Annealing up to T(a) of about 755 K causes increases in crystallite size, crystalline orientation, and linear degree of order, combined with an improved axial Young's modulus E. Thermal degradation at higher temperatures leads to the breaking of tie molecules in general, while UV-radiation selectively damages tie molecules that are not taut.

Reduced radial distribution functions (RDFs) for non-crystalline solutions of poly(p-phenylene-1,3,4-oxadiazole) (POD) in H2SO4 have been determined and discussed for the first time. In solutions of up to 14 wt% POD in H2SO4 the POD monomeric units act as simple perturbations of the correlation lattice of the pure solvent. Between 14 and 15 wt% POD content a phase transition from isotropic solution to crystal solvates and H2SO4 occurs. The short range interactions of POD molecules with the correlation lattice of a 96.2 wt% aqueous H2SO4 solvent are considerably stronger than for the same POD content in a 100% H2SO4 solvent.

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.

Starting from the fundamental opportunities and regularities to produce high strength/high modulus materials from polymers, results will be presented concerning the mechanical properties and the structure formation of fibres and foils obtained by different methods of preparation as well as aspects of application. The zone-drawing of poly(ethylene terephthalate), the flow-controlled crystallization of polyethylene in solution, and the gel-spinning of ultrahigh molecular weight polyethylene will be described in detail.

The DSC-investigation of different concentrated sulphuric acid solutions shows that the results of this dynamic measurement method are in good agreement with those of steady state methods [1]. The diverse DSC-melting peaks can be interpreted by using the known behaviour of the system SO3/H2O [1] as the melting of different congruent melting phases or eutectics, respectively. The observed melting enthalpies are in the correct order.

Concentrated solutions of poly(p-phenylene-l,3,4-oxadiazole) (POD) exhibit high flow birefringence at shearing. This is an indication of the high orientation of the polymer molecules in the solution. At high shearing rates the rheological investigations point t o an irregularity of the viscosity similar t o nematic polymer solutions. DSC investigations of the melting behaviour of the components of the solvent suggest increasing interaction between POD and H 2 SO 4 with decreasing concentration of the sulfuric acid.

The solution properties of poly(p-phenylene-1,3,4-oxadiazole) (POD) in concentrated sulfuric acid are described on base of literature results and own experimental investigations. In concentrated POD solutions (polymer content ≧ 15% by wt) crystalline structures with spherulitic morphology are formed, which were assigned to the crystal sol-vate modification as described by M ILKOVA et al.

Fibers were produced from two commercial grade linear polyethylenes (PE) of different molecular weight by flow-induced crystallization. DSC measurements were carried out with an annealing and melting program lour melting peaks were found. The first peak, at the lowest temperature, can be identified with the melting of lamellar crystallized PE. Peak 2 corresponds to the melting of the main crystalline fraction of the fiber. and peaks 3 and 4 to the melting of constrained crystalline regions. The melting temperature depends on the molecular weight of the fiber material and on the drawing state.

Under the condition of inhibited shrinking the dynamic melting and recrystallization was investigated by differential scanning calorimetry with polyethylene. The melting of regions having different order was found to be not independent.

A literature review is presented on the methods of characterization of the mesomorphic structures occuring in solutions of cellulose and cellulose derivatives. Experiments performed by the authors with the aim to characterize the liquidcrystalline states in solutions of cellulose derivatives allow the comparative estimation of the validity of current methods and complete the experience gained with these solutions.

Using the method of hot drawing developed earlier, an attempt has been made to obtain ultra-high modulus and ultrahigh strength PE filaments from original filaments produced by the “surface growth” technique. The average tensile strength of the drawn fibers reaches 5.5 GPa and the value of modulus measured in a dead loading creep experiment is estimated to be 44 GPa. 13 % of the drawn specimens had extremely high tensile strength close to theoretical estimates. The great scatter of the tensile strength data is attributed to the kink-band formation in the specimens due to their bending during preparation or during drawing.

Acta PolymericaVolume 34, Issue 7 p. 448-448 New Book Dynamische thermische Analysenmethoden. 2. Auflage. Von KLAUS HEIDE. Leipzig: VEB Deutscher Verlag für die Grundstoffindustrie 1982. 311 S., Lwd., geb., M 48,– P. Weigel, P. WeigelSearch for more papers by this author P. Weigel, P. WeigelSearch for more papers by this author First published: July 1983 https://doi.org/10.1002/actp.1983.010340721AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume34, Issue7July 1983Pages 448-448 RelatedInformation