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  • 11
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 769-783 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of crystallization kinetics were made for a sample of poly(α,α-diethyl-β-propiolactone) (DEPL) (syst. name: poly(oxy-2,2-diethyl-1-oxotrimethylene)). An Avrami exponent of 2 was found indicating a two-dimensional growth rate of the crystal, following a pre-determined and heterogeneous nucleation mode. Two melting peaks were found for most samples. The second melting peak (at high temperatures) is probably due to the re-crystallization of part of the sample initially present under the first melting peak. A value of 21kJ.mol-1 was also determined for the heat of fusion of DEPL by the diluent method. This value leads to a degree of crystallinity of 17% which is about four times smaller than that found for poly(pivalolactone) (syst. name: poly(oxy-2,2-dimethyl-1-oxotrimethylene)). We have also determined an equilibrium melting temperature of 531 K for this polymer and an entropy of fusion of 40J.mol-1. K-1. Finally, the surface free energies σ and σe for the lamellar crystals were found to be 12.10-7J.cm-2 and 72.10-7J.cm-2, respectively.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 857-867 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscoelastic properties of poly(α,α-diethyl-β-propiolactone) were investigated in the linear range using stress relaxation and dynamic mechanical methods. Using Ferry's reduction method, a horizontal shift factor was determined at each temperature, that satisfactorily agreed with the WLF equation in the transition zone. No vertical shift was required to superimpose different relaxation curves. The apparent activation energy was temperature dependent and passed through a maximum near Tg whose value is (311 ± 2)K. The relaxation spectrum has been calculated according to the first method of approximation of Schwarzl and Staverman. It consists of a high intensity plateau at shorter times, a wedge type portion with a slope of -0,15 and a low intensity plateau at longer times. Dynamical mechanical measurements revealed a β relaxation peak at 333 K and yielded the evidence of a γ peak around 120 K.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 2705-2718 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Oriented fibers of polypivalolactone (PPL) were melted in a differential scanning calorimeter. Two peaks were observed at the temperatures 507 and 512 K. Wide angle X-ray patterns indicate that these are due to helical and planar zig-zag conformations of the PPL chains. After melting and recrystallizing these samples, melting peaks at 495 and 507 K were observed. They correspond to two different crystalline modifications of PPL. By changing the crystallization and annealing conditions, each of the two modifications can be isolated or prepared in various proportions.
    Notes: Des fibres orientées de polypivalolactone (PPL) ont été fondues dans un calorimètre enthalpique différentiel (DSC). Deux pics sont alors obtenus à des températures de 507 et 512 K. Ils correspondent à des phases formées de chaǐnes hélicoïdales et zig-zag planaires respectivement, tel que démontré par la méthode des rayons-X. Après la fonte et la recristallisation des ces měmes échantillons, deux pics de fusion sont révélés à des températures de 495 et 507 K. Ils correspondent à deux modifications cristallines différentes du PPL. Suivant les conditions de cristallisation et de recuit, chacune de ces deux modifications peut ětre isolée, ou un mélange des deux peut co-exister.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2407-2414 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The behavior of methacrylic side chain polymers in an electric field was observed for a homopolymer (1) exhibiting a negative dielectric anisotropy compared with a copolymer (2) of positive dielectric anisotropy. Homopolymer 1 orients spontaneously homeotropic and thus enables the determination of the threshold voltage, rise time and decay time. Based on these experimental results the bend elastic constant and viscosity coefficient were estimated using literature values for the dielectric anisotropy. With respect to the bend elastic constant and electrohydrodynamic effects (e.g. Williams Domains) the homopolymer behaves similarly to low-molar-mass liquid crystals, while owing to the high viscosity coefficient response times are large in magnitude.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1195-1204 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method of obtaining good quality ultrathin sections from nylon 6 bulk samples has been developed by using a special embedding technique and cryo-ultramicrotomy. The morphologies of nylon 6 processed by compression and injection molding and of reaction injection molded nylon 6 were studied in ultrathin sections of bulk samples by means of transmission electron microscopy. It was established that the spherulites of nylon 6 in bulk are built up from long flat ribbonlike lamellae. The thickness of the lamellae is in the range 50-60 Å. The width varies from 150 to 600 Å and depends on the type of nylon 6 and the method of processing. The length of the lamellae is relatively large approaching spherulite radii, extending often from the point of their origin up to the spherulite borders. Three or four neighboring lamellae within spherulites usually show similar orientation of their flat faces and form domains which can easily be mistaken for fibrils in light microscopy or low resolution electron microscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 431-439 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The origin of the curious “inverted contrast” often observed in transmission electron micrographs of crazes in rubber-toughened thermoplastics was determined by using scanning transmission electron microscopy with X-ray fluorescence analysis. The “black crazes” seen in the micrographs contain high concentrations of osmium metal which is introduced through OsO4 used to stain the rubber phase. Treatment of stained sections with a strong oxidizing agent (NaIO4) removes a sufficient amount of osmium to reveal the commonly observed tufty craze microstructure with the expected contrast of light crazes in a darker background.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of perdeuterated polybutadiene and a styrene-butadiene diblock copolymer (polystyrene-block-polybutadiene) were prepared by solution-casting techniques. Small-angle neutron scattering and transmission electron microscopy experiments on blends containing homopolymer with chain length smaller than the corresponding block sequence showed that homopolymer chains are solubilized by the spherical microdomains up to a homopolymer content of about 15 mol-percnt;. The solubilized homopolymer is distributed in a spatially uniform manner throughout the domain volume and the radius of gyration of the homopolymer is only slightly larger than that of an unperturbed chain in bulk. At about 18 mol-percnt;, pools of homopolymer appear outside the microdomains; the change in scattering intensities indicates that pool formation is a kinetic phenomenon rather than a thermodynamically controlled event. Experiments on blends containing longer homopolymer chains revealed a lower concentration, between 3 and 6 mol-percnt;, for the onset of homopolymer pool formation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanism by which water and dissolved salts permeate selectively through membranes has been investigated. It has been demonstrated that the predominant mechanism of permeation involves the interaction of the various species with specific sites and their associated bound water molecules. The extent of the bound water held by the cellulosic membranes of interest has been determined. Correlation has been found between the permeation characteristics demonstrated by membranes at various steps in their preparation and its bound water content. The mechanism of rejection of salts has been shown to be related to the relative inability of their ions to become solvated by bound water. A model has been hypothesized which correctly describes the behavior of the desalination membrane with reference to water and soluble inorganic salts.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1035-1047 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The terpolymerization of N,N′-terephthalonitrile oxide (TPNO), 1,3,5-tricyanobenzene, and oligomeric perfluoroalkylene dinitriles derived from the oligomerization of tetrafluoroethylene oxide yields poly(perfluoroether)-1,2,4-oxadiazole polymers which are soluble in Freon TF and bear pendent nitrile groups as curing sites. The polymerization is a two-step, ambient-temperature reaction. Several different perfluoroether dinitriles are shown to polymerize using this procedure. The syntheses and certain structure/property relationships of the polymers are discussed. Increasing the chain length of the perfluoroalkylene oxide dinitriles results in polymers which range from paraffin-like solids through tough elastomers and, finally, to tacky gums. Tough, crepe elastomer gum with a Tg of -64°C may be obtained in yields of 60-70%. The poly(perfluoroether) oxadiazoles may be milled with additional TPNO and press cured at 95°C (200°F). The following physical properties of the cured polymers are given: compression set, tensile strength, per cent elongation at break, set at break, and Shore A hardness. Thermal stability, moisture stability, and low-temperature flexibility data are also presented for the cured elastomeric polymer.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 559-568 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(caprolactone) (PCL) was blended with poly(chlorostyrene) (PSCI) and chlorinated polypropylene (PPCl). A single glass transition temperature Tg was found for these mixtures, indicating their miscibility. PCL crystallizes in these blends when the chlorinated polymer content is not too high. Otherwise, Tg becomes higher than the melting point of PCL and the high viscosity of the medium hinders the crystallization. The miscibility of PCL/PPCI blends cannot be due to hydrogen bonding between the α-hydrogens of the chlorinated polymer and the carbonyl group of the polyester since PPCI does not have available a large number of α-hydrogens. It is suggested that a dipoledipole —C=O…Cl—C— interaction is responsible for the observed miscibility phenomenon and that this interaction is probably also responsible for the miscibility between all other polyesterchlorinated polymer mixtures. Finally, it was observed that poly(α-methyl-α-n-propyl-β-propiolactone), poly(α-methyl-α-ethyl-β-propiolactone) and poly(valerolactone) are not miscible with PSCI or PPCl, despite the fact that they are miscible with poly(vinyl chloride).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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