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  • 1
    Digitale Medien
    Digitale Medien
    Cis-Trans Isomorphism in 1,4-Bis(aminomethyl)cyclohexane Polyamides (1972)
    s.l. : American Chemical Society
    Macromolecules 5 (1972), S. 168-170 
    Details
    ISSN: 1520-5835
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ma60026a014
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  • 2
    Digitale Medien
    Digitale Medien
    Crystallographic and morphological studies of electrolytic zinc dendrites grown from alkaline zincate solutions (1973)
    Springer
    Journal of materials science 8 (1973), S. 79-87 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Electrolytic zinc dendrites grown potentiostatically from a range of alkaline zincate solutions were studied using X-ray diffraction and scanning electron microscopy (SEM) to reveal structural and morphological characteristics as a function of their growth rate. Conclusions from this work were as follows: Dendrites grown at a rate of 3 μm min−1 were identified as twinned monocrystalline “swords” with a noticeable absence of regular branching. Dendrites grown at a rate of 24 μm min−1 were basically twinned monocrystals with some polycrystalline character. As for the slowest growing dendrites, the morphological character was of a sword-like nature. Morphologically these first two types of dendrites show great similarity to the butterfly dendrites of DeVries. Dendrites grown at 67 μm min−1 were of the fern-like morphological type with a large degree of polycrystalline character. These dendrites are suggested as being composites of very small slow growth rate dendrites in a roof tile arrangement. The results for the ideal fern-like dendrites seemingly disagree with the earlier hcp dendrite work of Wranglen who identified this type of dendrite as a monocrystal. An explanation for this discrepancy is offered. The work presented here appears to be consistent with the twin plane re-entrant edge (TPRE) growth mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00755585
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  • 3
    Digitale Medien
    Digitale Medien
    Crystallographic studies of nylon 4. I. Determination of the crystal structure of the α polymorph of nylon 4Paper presented at the First Middle Atlantic Regional Meeting of the American Chemical Society, Philadelphia, February 4, 1966. (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 899-911 
    Details
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The crystal structure of the α polymorph of nylon 4 has been determined from the x-ray diffraction patterns of uniaxially oriented monofilaments. In general the crystal structure of α nylon 4 is similar to that of α nylon 6. The unit cell is monoclinic with the following dimensions: a = 9.29 ± 0.05 A., b = 12.24 ± 0.05 A., c = 7.97 ± 0.05 A., and β = 114.5 ± 1.0°. There are eight monomeric units in the unit cell. The theoretical density is 1.37 g./cc. and the observed density 1.25 g./cc. The space group is P21. The nylon 4 chains are of the extended planar zigzag type, with the plane of the zigzag approximately parallel to the a axis of the unit cell. Along the a axis, every other chain is inverted - an antiparallel arrangement of chains - thus permitting complete hydrogen bonding and the formation of sheets of nylon 4 chains. Along the c axis of the unit cell, the second sheet is displaced by3/10 of the b axis, thus leading to a staggered arrangement of sheets. The sheets are held in place by van der Waals forces.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1966.160040606
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  • 4
    Digitale Medien
    Digitale Medien
    Crystallographic studies of nylon 4. II. On the β and δ polymorphs of nylon 4Paper presented at the First Middle Atlantic Regional Meeting of the American Chemical Society in Philadelphia, February 4, 1966. (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 913-922 
    Details
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In addition to the α polymorph, two crystalline forms of nylon 4, the β and δ polymorphs, have been observed and studied.The β polymorph of nylon 4, which has not been found in a pure condition, appears to be similar to the β polymorph of nylon 6. The extended planar zigzag conformation of chains, found in the α polymorph, is present also in the β polymorph. Three models have been proposed to explain the observed data. In model 1, the staggered shear of van der Waals bonded sheets found in the α polymorph is abandoned; in model 2, the sheets are displaced by 1/2 the b axis, and in model 3 the chains are arranged in a parallel array. The β polymorph is converted to the α form in air upon heating for 11 min. at 227°C. and upon immersion in water for 2 hr. Models 1 and 2 would be converted to the α polymorph by a slippage of the van der Waals bonded sheets while the conversion from model 3 would involve a rupture of hydrogen bonds, a rotation of the chains through 90°, and the reformation of hydrogen bonds. The δ polymorph is formed by rapidly quenching extruded nylon 4 against chilled rolls. It is a metastable form which has only been observed in an unoriented condition. Upon orientation it is completely converted to the α polymorph. In addition to this, its conversion to the α form occurs under conditions similar to the β-α transition. The observed diffraction pattern can be indexed on the basis of a hexagonal packing of chains. High-temperature x-ray diffraction studies of the α polymorph suggest that the δ form, or a structure similar to it, is the high-temperature form of nylon 4.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1966.160040607
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  • 5
    Digitale Medien
    Digitale Medien
    Studies of the morphology of emulsion-grade polytetrafluoroethylene (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1337-1349 
    Details
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Two types of emulsion-grade polytetrafluoroethylene particles have been studied. We refer to these as ribbons and rods. The ribbons consist of very thin ribbons or lamellae folded upon themselves a number of times. In typical emulsion-grade material prepared at Allied Chemical, the unraveled ribbon measures about 3.25 μ in length, 0.25 μ in width, and 60Å in thickness. The folded ribbons, which form the particles, are about 0.5 μ long and 0.25 μ wide. Electron diffraction shows that the ribbons are single crystals with the chain axis parallel to the long axis of the ribbons thus forming extended chain crystals. This extended-chain packing is consistent with the observed cleavage or fibrillation of the ribbons and with the molecular weight. The rods are formed in low-yield polymerizations. Electron diffraction also shows that the rods are single crystals with the chain axis parallel to the long axis of the rods. Striations parallel to the long axis are believed to result from stacking of parallel segments. Considerable bending of the long axis of rods is observed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1972.160100712
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  • 6
    Digitale Medien
    Digitale Medien
    Crystallinity in poly-N-methyllaurolactam and copolymers (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1699-1707 
    Details
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Fully methylated nylon 12 was prepared by the hydrolytic polymerization of N-methyllaurolactam. The polymer, with about 20% crystallinity, has a crystal structure different from that of nylon 12. The X-ray diffraction patterns of copolymers of N-methyllaurolactam and laurolactam were shown to be composition-dependent. Copolymers containing up to 15% laurolactam units exhibited a crystal structure essentially the same as poly-N-methyllaurolactam. Copolymers containing from 20 to 50% laurolactam are transition structures, whereas copolymers containing more than 50% laurolactam units exhibit a crystal structure characteristic of polylaurolactam. DSC data on the homopolymers and copolymers are also reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1972.160100906
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  • 7
    Digitale Medien
    Digitale Medien
    Morphological and structural changes in a copolymer of glycolide and lactide occurring as a result of hydrolysis (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 57-66 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The changes in the structure and morphology of a random copolymer containing 92 mol % glycolide units and 8 mol % lactide units as a function of in vitro hydrolysis have been studied. A number of techniques, such as wide-angle x-ray diffraction, small-angle x-ray scattering, density measurements, infrared spectroscopy, and viscometry were employed in this study. The results showed that the hydrolytic attack was initiated in the amorphous areas of the polymer. After 28 days in the in vitro medium most of the amorphous areas had been chemically converted to lower-molecular-weight species such as oligomers of poly(glycolide-co-lactide). These low-molecular-weight species become water solble and are removed rapidly after day 28. Thus the fiber takes on a Swiss cheese character as the amorphous matter is hydrolyzed and eventually dissolved. As hydrolysis proceeds further, the crystalline areas of the polymer are attacked and eventually removed from the fiber by solubilization. The resulting voids in the fiber are eventually filled by a “collapse” of the structure. The role of the amorphous areas of the polymer in controlling the tensile strength of the suture is discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1984.180220106
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  • 8
    Digitale Medien
    Digitale Medien
    Effect of N-substitution on the crystallinity of polylaurolactam (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 939-949 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Poly(N-ethyl laurolactam) and poly(N-benzyl laurolactam) were prepared from the corresponding monomers by hydrolyic polymerization. Unlike the partially crystalline poly(N-methyl laurolactam), these two homopolymers were completely amorphous by x-ray diffraction. Diffraction patterns of copolymers of N-ethyl laurolactam or N-benzyl laurolactam with laurolactam were shown to be composition-dependent. For N-ethyl laurolactam copolymers, crystallinity developed with 20% laurolactam as a comonomer and increased steadily with a subsequent change in the x-ray pattern, up to 50% laurolactam. Higher laurolactam percentages resulted in copolymers having a nylon 12 x-ray pattern. N-Benzyl laurolactam copolymers with 30% laurolactam showed only 6% crystallinity. The x-ray patterns of N-benzylated nylon 12 made with more than 50% laurolactam showed patterns similar to that of nylon 12. Differential scanning calorimetry data of all these polymers substantiate the x-ray findings. The effect of type and concentration of the N-substituent on the glass transition, melting, and crystallization temperatures of the polymers is discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1973.180110511
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  • 9
    Digitale Medien
    Digitale Medien
    Structure and thermal stability of aliphatic polyoxamides (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1-14 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A homologous series of aliphatic polyoxamides, nylon 122, 102, 82, and 62, were prepared by the bulk polycondensation of dialkyl oxalates with diamines. Infrared spectroscopy, x-ray diffraction, differential thermal analysis, thermogravimetric analysis, and gas chromatography were used to study the structure and thermal stability of these polyoxamides. From the fiber pattern of nylon 122, a structural repeat distance of 19.5 Å was measured. This was in close agreement with the expected value for an extended planar, zigzag chain conformation. With the exception of the expected decrease in the structural repeat distance along the chain axis resulting from the different number of methylene groups, nylons 122, 102, and 82 were isostructural. Nylon 62 appeared to pack in a similar manner to the other materials studied. However, there were differences in the diffraction pattern of this polymer; these may be indicative of a different chain conformation or of strain in the crystalline regions of the polymer. The infrared spectra indicate the presence of strong hydrogen bonding in all the polymers. Thermal analysis and pyrolysis data revealed catastrophic polymer degradation between 400 and 500°C in nitrogen, with appreciable homolytic cleavage of the oxamide group.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1973.180110101
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  • 10
    Digitale Medien
    Digitale Medien
    Isomorphous replacement in nylon 6 by 4-aminomethylcyclohexanecarboxylic acid (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 3533-3541 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It was desired to determine the effect of geometric configuration on the ability of 4-aminomethylcyclohexanecarboxylic acid (AMCC) to “isomorphously” replace ε-aminocaproic acid residues in nylon 6. However, we found that cis-AMCC isomerized to the more thermodynamically stable trans isomer during copolymerization with caprolactam (CL) and also during homopolymerization. A 20/80 cis/trans ratio of AMCC residues was found in the 50:50 copolyamides regardless of whether a high-cis (72/28) or high-trans (15/85) AMCC was used. Powder x-ray diagrams showed similar interplanar spacings for the copolyamides made from both high-cis and high-trans AMCC. The x-ray study also showed that the nylon 6 lattice can accommodate less than 30 mole-% AMCC residues before a new structure appears. DTA and TGA data of the CL:AMCC copolyamide showed that AMCC raised the melting point, Tg, Tc, and stability of nylon 6.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1970.150081215
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