摘要:

AbstractAmorphous samples of polyethylene terephthalate were stretched with different rates and stretching ratios at different temperatures. Afterwards they were crystallized. The arrangement of the crystals and the conformations of the chains in the noncrystalline regions were investigated by means of X‐ray wide‐angle scattering, X‐ray small‐angle scattering, birefringence measurements and nuclear magnetic resonance measurements. The influence of the morphological structure on the mechanical strength was determined. The stretching ratio itself generally does not characterize the orientation state. The structure obtained after crystallization depends mainly on the birefringence of the sample after stretching before crystallization. With increasing birefringence one obtains all intermediate structures starting from the well known spherulites composed of twisted lamellae in the unoriented material up to a paracrystalline lattice of lamellae split up into mosaic blocks in the highly oriented state. Also the conformations of the chains in the noncrystalline regions are influenced by the stretching. With increasing orientation the amount of tie molecules with comparatively large end‐to‐end distances becomes larger. The improvement of the mechanical properties with stretching is caused not only by the increasing orientation of the molecules but also by the increasing amount of taut ti

ISSN:0360-8905    

DOI:10.1002/polc.5070580113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractStress distribution among the polymer chain segments and parameters of the supermolecular structure of oriented polypropylene, polyethylene terephthalate and polycaproamide films have been compared. The stresses have been determined by infrared spectroscopy, and the structure has been studied by electron microscopy and small‐angle and wide‐angle X‐ray scattering. The polymers studied are shown to have a microfibrillar structure. The sizes of long periods, the lengths of crystallites and amorphous regions are found. Stress distribution among the polymer chain segments is extremely nonuniform. Most of the segments, i.e., 90–95%, are subjected to stresses close to the applied stress, the rest of the segments, i.e., 5–10%, experience stresses which are at least an order of magnitude higher. Highly overstressed segments lie in the amorphous regions of microfibrils. They bear the major part of the applied load (not less than 80–90%). A model for the amorphous regions' structure of microfibrils in oriented polymers i

ISSN:0360-8905    

DOI:10.1002/polc.5070580114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

ISSN:0360-8905    

DOI:10.1002/polc.5070580115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractFibers from bisphenol‐A polycarbonate are typical representatives of the less crystallizing synthetic fibers. Because of the high glass transition temperature, textiles produced from these fibers have outstanding laundry‐resistance and noncreasing properties. Polycarbonate fibers can be produced both by the dry or wet‐spin and by the melt‐spin process. The stretching of the fibers is carried out in accordance with the proposed textile characteristics below or above the glass transition temperature or by a special swelling–drawing process, in the course of which fibers of particularly high tenacity and elastic modulus can be obtained. The fibers produced by the latter process were investigated by a number of physical measurements of their morphological structure (density, birefringence, X‐ray wide‐ and small‐angle scattering, differential calorimetry, thermo‐mechanical analysis). These measured values of density, birefringence, and heat of fusion show that these fibers have a higher degree of crystallinity than the fibers produced by a melt or dry spinning process. Whereas with dry‐spun fibers an increase in tenacity can be obtained by raising the molecular orientation up to a limited tenacity value, it is possible with fibers produced by the swelling‐drawing process to virtually double the tenacity due to the higher crystallinity and improved crystal structure (creation of a large number of physical linkages). By means of X‐ray small‐angle scattering on annealed swollen‐drawn polycarbonate fibers, we were able to detect, for the first time, a marked two‐phase structure consisting of crystalline and noncrystalline regions with a long‐period of about 120 Å. With other crystalline polymers, a period of this ki

ISSN:0360-8905    

DOI:10.1002/polc.5070580116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA detailed structural characterization of three aromatic polyamide (PPT) fibers has been carried out by means of direct electron microscope observations and X‐ray and electron diffraction analysis. Data obtained by the diffraction techniques are supplemented by high‐resolution images recorded from fragmented specimens, which provide both a qualitative assessment and quantitative information in terms of crystallite perfection and the distribution of crystallite size. Dark‐field images suggest major differences between the macrostructures of various PPT fibers; indeed some specimens are composed of long‐range axially periodic assemblies, while others appear to be homogeneous. Such differences in organization may well account for variations in tensile b

ISSN:0360-8905    

DOI:10.1002/polc.5070580117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractFibers from mixtures of two polypropylene types were produced with the same conditions. The polymer base was a normal fiber grade polymer to which a high molecular weight polypropylene was added in amounts of 25, 50, and 75%. The extensibility of the fibers changed considerably by increasing the high polymer amount. The tensile properties were measured and compared with measured structural properties, such as crystallinity, crystalline particle size, amorphous orientation, amorphous region derived from small and wide‐angle X‐ray scattering. New terms, the specific amorphous orientation and the structural deformability index, were proposed, and it was shown that the tensile properties, i.e., strength, elongation at break, initial modulus and sonic modulus, are in very good correlation with t

ISSN:0360-8905    

DOI:10.1002/polc.5070580118

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe morphology of polymers having fiber texture is commonly considered to consist of a fibrillar structure. The author proposes a method for the quantitative description of the internal structure of the fibrils by analysis of X‐ray small‐angle scattering patterns. A theoretically relevant quantity, “morphology index” (μ) characterizing the fibril morphology can be calculated from structure parameters. Microfibrillar (μ » 1) and lamellar (μ « 1) structures represent limiting cases of the actual structural order. The dependence of μ on the temperature was determined for a series of fixed ends annealed polyamide‐6 filaments. A distinct change from the microfibrillar to the lamellar structure was verified, with slight increase of the microfibrillar character up to 140°C. With drawn polyamide‐6 samples the morphology index remains unchanged, in spite of slight changes of individual parameters, such as crystallite size, and weak shearing of fibrils. This suggests that drawing does not lead to essential changes of the internal st

ISSN:0360-8905    

DOI:10.1002/polc.5070580119

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractOn the basis of a single‐phase structural model a theory has been developed, which yields a relation between the fiber compliance and the chain axis distribution. It is shown that this relation, viz.\documentclass{article}\pagestyle{empty}\begin{document}$$ S_{33} = e_3^{- 1} + A\left({\sin ^2 \phi} \right) + B\left({\sin ^4 \phi} \right) $$\end{document}Is quantitatively fulfilled for poly(p‐phenylene terephthalamide) fibers studied in this investigat

ISSN:0360-8905    

DOI:10.1002/polc.5070580120

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractX‐ray diffraction techniques, optical microscopy, and scanning electron microscopy have been used to study a series of melt‐spun bi‐constituent fibers containing isotactic polypropylene and nylon 11. The addition of small amounts of nylon 11 produces bimodal crystal texture in polypropylene with most crystallites having either their c‐axes or a‐axes oriented nearly parallel to the fiber axis. In blends containing about 50% nylon 11 a third polypropylene crystallite orientation is observed in which the [101] directions are oriented nearly parallel to the fiber axis. The polypropylene chain axes make an angle of about 50° to the fiber axis, and an additional set of layer lines is produced. In blends containing more than 50% nylon 11, most of the polypropylene crystallites adopt the third orientation. It is suggested that this third orientation of polypropylene crystallites is the result of epitaxy on portions of nylon 11 fold surface at the interface between the two

ISSN:0360-8905    

DOI:10.1002/polc.5070580121

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

ISSN:0360-8905    

DOI:10.1002/polc.5070580122

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY