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  • 1
    Electronic Resource
    Electronic Resource
    Stretching-Induced Correlations in Triblock Copolymer Gels As Observed by Small-Angle Neutron Scattering (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 8699-8701 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00129a035
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  • 2
    Electronic Resource
    Electronic Resource
    A kinetic analysis of the assembly of microtubules in vitro
    Amsterdam : Elsevier
    FEBS Letters 80 (1977), S. 81-85 
    Details
    ISSN: 0014-5793
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(77)80411-0
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  • 3
    Electronic Resource
    Electronic Resource
    Cycloaddition reactions of azides with electron-poor olefins - Isomerization and thermolysis of the resulting Δ^2-triazolines
    Amsterdam : Elsevier
    Tetrahedron 27 (1971), S. 3527-3534 
    Details
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0040-4020(01)97763-4
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallization of poly(ethylene terephthalate) induced by inorganic compounds. I. Crystallization behavior from the glassy state in a low-temperature regionThis paper was presented in part at the IUPAC Symposium on Macromolecules in Leiden, 1970. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 303-316 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of isothermal crystallization from the glassy state at low temperatures and the morphology of poly(ethylene terephthalate) (PET) filled with additives are reported. Talc, kaolin, silicon oxide, and titanium oxide have been used as fillers; they act as effective nucleating agents for PET. The overall rate of crystallization depends on the volume concentration, the size distribution, and the nucleating ability of the additives. An electron microscopic study reveals a transcrystalline morphology at the surface of the filler particles. The occurrence of transcrystallinity is attributed to extensive heterogeneous nucleation induced at the filler surface. From the shape of the crystallization isotherms, it can be concluded that the crystallization mechanism depends on the type of filler.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120207
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  • 5
    Electronic Resource
    Electronic Resource
    Crystallization and melting of the system isotactic polystyrene + poly(2,6-dimethyl phenylene oxide) (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1757-1767 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: From glass transition Tg measurements on isotactic polystyrene (IPS)-poly(2,6-dimethyl phenylene oxide) (PPO) blends, it was concluded that thoroughly annealed, freeze-dried samples, or samples evaporated from solution at high temperature, are homogeneous. Without annealing, the freeze-dried blends show two to three Tg's characteristic of the presence of different phases. The overall crystallization rate of these samples is much higher than that observed with annealed samples. The presence of dissolved PPO in annealed samples reduces the overall crystallization rate and the spherulitic growth rate, compared to IPS. The melting behavior of the blends is influenced by the extent of mixing of both polymers. Without annealing, isothermally crystallized, freeze-dried blends show the same melting behavior as IPS (i.e., multiple melting). In homogeneous annealed samples the rate of reorganization is strongly reduced and multiple melting only occurs at low scanning rate (e.g., 1°C/min). This behavior is influenced by the crystallization temperature and by the composition of the blends. The addition of PPO has no influence on the relation between melting point and crystallization temperature and the same equilibrium melting point is found by extrapolation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.180151006
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  • 6
    Electronic Resource
    Electronic Resource
    Solution grown isotactic polystyrene crystals. II. Kinetics of thermal changes by x-ray diffraction (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1485-1500 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The present paper is a study of the annealing, melting, and recrystallization behavior of solution grown isotactic polystyrene crystals in order to elucidate changes both in total lamellar thickness and in the thickness of the crystalline “core” as a function of temperature. The lamellar thickness was obtained from x-ray long spacings and the core thickness from the broadening of appropriate reflections, both assessed by a high sensitivity x-ray detector system able to produce records within a few minutes during time dependent processes. The x-ray results were correlated with differential scanning calorimetry (DSC) measurements. On heating, first the usual annealing effects with little net melting were observed, but on increasing the temperature large changes in long spacing, which were reversible with temperature, were seen accompanied by only small changes in crystal core thickness. The second effect was found to be associated with a substantial degree of melting. Even after heating above the temperature where complete melting was indicated by DSC, the recrystallization rate was found to decrease as the melt temperature was increased and to be much faster than on cooling from the usual melts. Strikingly, this recrystallization was accompanied by a decrease in long period with time even under isothermal conditions. It is inferred that the memory of the preceding crystalline stack is preserved throughout the melting range and even beyond this, far into the molten state. This “seeding” effect is intrinsic to the polymer even if its nature cannot be specified. The principal effects in question can then be explained by envisaging that randomly placed lamellas gradually disappear within the stack on melting and successively reappear on crystallization during cooling. These ideas agree well with previous work on reversible long spacing changes in polyethylene (see ref. 9) and are likely to be of wider generality for melting and recrystallization phenomena in systems having stacked lamellar morphologies.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.180150813
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  • 7
    Electronic Resource
    Electronic Resource
    Gelation-crystallization in isotactic polystyrene solutions and its implications to crystal morphology, to the origin and structure of gels, and to the chemical homogeneity of polyolefins (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 39-61 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As part of a wider study on the crystallization of isotactic polystyrene solutions it was observed that at sufficient concentrations (〉 3-5%) gelation sets in below a certain (very high) supercooling in competition with the usual single crystal formation which in itself produces turbid suspensions. It was established that gelation is a form of crystallization (mode A) which must be of fringed micellar type to provide the connectedness as opposed to the chain folded lamellae (mode B) which gives rise to discrete particles. The gel crystals (A) display sharp melt endotherms and produce distinct x-ray diffraction patterns both of which, however, differ decisively from those provided by crystals B, a distinction which can be preserved even after removal of the solvent. The melting points of A are significantly lower than those of B and the x-ray diffraction patterns of A are incompatible with the recognized structure of polystyrene (31 helix) possessed by B; they point to a broadly planar zig-zag arrangement of the chain. This strongly suggests that we have blocks of chemically distinct sequences which could be syndiotactic or head-to-head tail-to-tail (presently with substantial support for the latter) which is responsible for the gel forming crystallization. However, so far the C13 nuclear magnetic resonance (NMR) results do not provide the evidence for these distinct species but explanations for our observations on any other basis seem to lead to unsuperable difficulties from other points of view. Consequently, the paper is left open ended with the possibilities discussed. Amongst these the existence of a very few but long, chemically distinct sequences seems most attractive. The wider implications of the facts as they stand for crystal morphology (fringed micelles versus lamellae), for the origin and structure of gels in general, for the crystallization of block copolymers and for issues relating to chemical homogeneity (tacticity, head-to-head tail-to-tail) are discussed and preliminary effects are quoted which indicate that these issues may also be relevant to the usual atactic polymers.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140104
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of crystallization and annealing conditions on the morphology of bulk-crystallized isotactic polystyrene (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1177-1186 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of thermal history on the morphology of bulk-crystallized isotactic polystyrene was investigated. Results from x-ray diffraction (both wide- and small-angle), DSC experiments, and electron microscope observations, were combined to define the influence of thermal history on the fold surface free energy σe. lamellar thickness, and crystallite perfection. The increase of the melting point with crystallization temperature is not only the consequence of an increase in lamellar thickness, but also of marked decrease of σe. Annealing above the crystallization temperature results in a fast reorganization to a more stable structure, as reflected in an increase in melting point. This reorganization, depending on the crystallization temperature, involves an increase in lamellar thickness, a decrease of σe, and eventually an increase in crystallite perfection.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140703
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  • 9
    Electronic Resource
    Electronic Resource
    Solution grown isotactic polystyrene crystals. I. Degree and distribution of crystallinity; thermal stability (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1475-1483 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The subject of this paper is the degree of crystallinity and annealing behavior of solution grown single crystals of isotactic polystyrene (IPS) in relation to the fold length, an enquiry which acquires special significance in view of the fact that previously the fold length had been found to be identical over a wide range of crystallization temperatures (Tc). It was found that both crystallinity and thermal stability increase with Tc even over the range of constant fold length thus invalidating the usual assumption that the fold length and crystal properties are uniquely correlated. Further, the crystallinity figures as measured by conventional calorimetry are very low (〈50% throughout) which by conventional ideas would require an unrealistically thick amorphous surface layer. However, the “linear crystallinity” (crystal core thickness as determined from x-ray linewidths) is much larger, commensurate with crystallinities in single crystals from other materials. It is suggested that this is the more relevant figure for the subdivision of the lamellas into crystal core and surface layer. The additional amorphous content being otherwise accommodated. Further, this “linear crystallinity” is broadly unaffected by fold length changes induced by heat annealing. The thermal stability (including annealing ability) of the crystals differs markedly whether Tc is above or below ∼60°C, a Tc value which is in the range where the fold length is constant, but corresponds to a maximum in the crystallization rate. Possible connections between crystallization conditions and the stability of the resulting crystals (fold length considerations apart) are pointed out.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.180150812
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  • 10
    Electronic Resource
    Electronic Resource
    Gelation and crystallization of poly(ethylene terephthalate-co-isophthalate) (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 1251-1267 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gelation of solutions of poly(ethylene terephthalate-co-isophthalate) depends on chain structure, solvent, temperature, and concentration. Wide-angle x-ray scattering and differential scanning calorimeter experiments reveal the crystalline nature of the gel. The crystalline crosslinks, with a fringed micellar structure, are composed of terephthalate units. Orientation of the dried gels reveals the presence of crystallites with their largest dimension parallel or perpendicular to the chain axis. At high enough concentration of crystallizing units in the chain, folded-chain lamellar structures are also formed. Compared with the fringed micellar crystallization, the induction time for this crystallization is short. Melting of the folded-chain structures is very similar to the melting of pure poly(ethylene terephthalate). Because of the crystalline nature of this gelation, copolymers with only a small difference in composition can be fractionated according to the difference in micro-structure.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.180170709
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