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  • Articles  (15,646)
  • Chemistry  (15,595)
  • 72.20
  • 73.60
  • 1985-1989  (13,637)
  • 1950-1954  (2,009)
  • Physics  (11,646)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (7,592)
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  • Articles  (15,646)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 45 (1988), S. 113-120 
    ISSN: 1432-0649
    Keywords: 78.65 ; 72.20 ; 72.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract There are a great variety of optical nonlinearities that can lead to the phenomenon of laser-induced gratings (LIG) in semiconductors. In the present contribution the dynamic behaviour of an induced absorber with intrinsic bistability is investigated under excitation in a LIG self-diffraction arrangement. Using CdS as a model substance, the comparison of our theoretical model with our experimental findings gives an insight into the nonlinear dynamics of the degenerate carrier system and also an estimation of the transport properties of the electron-hole plasma.
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  • 2
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    Applied physics 43 (1987), S. 205-208 
    ISSN: 1432-0630
    Keywords: 72.40 ; 72.20 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A transient negative photoconductivity phenomenon observed in silicon doped with gold atoms by an appropriate diffusion condition has been investigated. The transient negative photoconductivity could be observed with a diode doped with gold atoms under intrinsic light-pulse illumination. In the recovery process of the transient negative photoconductivity to a steady-state dark level, two kind of time constants were observed, which may be related with the emission of electrons from gold level. A dependence of the magnitude of the peak value on the ambient temperature was observed; a qualitative explanation is given.
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  • 3
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    Applied physics 37 (1985), S. 165-170 
    ISSN: 1432-0630
    Keywords: 71 ; 72.20 ; 78
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In thermally stimulated processes the calculation of the transition probability of a trapped charge carrier into an excited state is based on an atomistic model involving multiphonon processes. The displacement of lattice particles from equilibrium positions gives rise to electron-lattice interaction. As a result the temperature dependence is found to be of non-Arrhenius type except in some limiting cases. The difference of the probabilities for non-radiative transitions, as calculated by the quantum mechanical and by semi-classical methods, is discussed. Thermoluminescence proves to be an example for a non-radiative transition controlled phenomenon and the calculated glow curve differs appreciably from one model to the other. As a result the glow curves calculated in the quantum mechanical concept exhibit shapes which are broadened and shifted to lower temperatures, as compared to that calculated in the semi-classical concept. In turn, the activation energy, as determined by the initial rise method or the method of heating rate variation, is found to be much smaller in the quantum mechanical case.
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  • 4
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    Applied physics 37 (1985), S. 243-246 
    ISSN: 1432-0630
    Keywords: 68.20 ; 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A new possibility for using vacuum-evaporated CdS thin films in combination with a suitable organic polymer (e.g., polyethylene) in electrophotography is described. The advantages of a multi-layer type sample are discussed in terms of deep bulk trapping of the photogenerated free carriers, injected in the polymer. A formula is derived, which links the initial rate of surface potential decay with the trapping range in unit fieldμ 0τ. Using it and the data for the initial rates of surface potential decay of two samples (a double-layer and a multi-layer one), the trapping range for the vacuum-evaporated polyethylene films is determined.
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  • 5
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    Applied physics 41 (1986), S. 197-199 
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The noise current spectral density in submicrometer samples is computed using the Monte Carlo method. The normalized spectral density is found to decrease with sample length and increase with the field. The high-field noise is like shot noise and increases with current in agreement with experimental results.
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  • 6
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    Applied physics 42 (1987), S. 41-43 
    ISSN: 1432-0630
    Keywords: 72.20 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The instability of the electron-hole plasma produced by continuous photoexcitation in short semiconductor structures is investigated theoretically. The applied electric field is considerably disturbed by photogenerated charge carriers. At a sufficiently intensive photogeneration plasma instability occurs. The frequency of current oscillations due to the instability, as shown by numerical simulation for a GaAs structure, is in the range of 1011–1012s−1.
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  • 7
    ISSN: 1432-0630
    Keywords: 72.20 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Measurements of the Hall coefficients and of the resistivity of MBE-grown Si, doped with P, As, Sb, B, and Ga in the concentration range 1014 to 1020 cm−3, were carried out at 77 K and at 300 K. With the exception of Ga-doped Si, the measured mobilities were close to or higher than those of bulk materials at both temperatures. The Mott metal/non-metal transition has been observed in the present epitaxial materials and the measured values for the critical impurity concentration at which the transition occurs, agree with values reported by other workers for bulk silicon.
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  • 8
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    Applied physics 45 (1988), S. 77-81 
    ISSN: 1432-0630
    Keywords: 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The thermally induced electrical activation of boron implanted in silicon at fluences ≦1013 cm−2 was studied by the combination of secondary ion mass spectrometry (SIMS) and pulsed capacitance voltage (PCV). After annealing at 900°C for 30 min boron is completely ionized and the contribution of electrically active defects to the electrical profile is negligible. For partly annealed samples (T〈900°C) the degree of electrical activation of boron decreases with increasing boron concentration due to the presence of residual defects. The experimental data can be described qualitatively by the first-order kinetics if the influence of residual crystal defects on the electrical activation is considered.
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  • 9
    ISSN: 1432-0630
    Keywords: 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The nonlinearI – V behaviour and threshold switching of the bulk Se-Te-Sn system have been experimentally studied at various temperatures. It is observed that the curves are linear for low voltages and become superlinear at higher voltages. After a certain voltageV th, the current through the material shoots to a very high value and the potential across the material drops to a low value. It is also found that there is a decrease in Vh with increase in percentage of tin and temperature. An attempt is made to explain the nonlinearI – V behaviour and threshold switching on the basis of a microcrystallite model. A study of Se-Te-Sn system reveals that our results are in concurrence with the theoretical predictions.
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  • 10
    ISSN: 1432-0630
    Keywords: 61.40 ; 73.60 ; 78.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A series of experimental studies has been made on the relationship between optical and structural properties of hydrogenated amorphous silicon (a-Si:H) prepared under various conditions. It has been clarified by analysing the results that the shape of the energy spectrum near the band edge and the distribution of the valence-band tail states depend primarily on the structural disorder of the Si network in a-Si:H. On the other hand, the total content and the bonding mode of bonded hydrogen have little effects on these electronic properties of a-Si:H. It has also been found that the distribution of the valenceband tail states might be related to other unidentified factor(s) besides the structural disorder. The present results have been compared with those of the previous experimental and theoretical studies.
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  • 11
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    Applied physics 37 (1985), S. 153-164 
    ISSN: 1432-0630
    Keywords: 86.30 ; 72.40 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have made theoretical studies on the trapping and recombination of photogenerated carriers in hydrogenated amorphous silicon (a-Si∶H) p-i-n solar cells. We discuss in detail the following points: 1) The limitations of the assumptions in the previous analysis. It has been clarified that the single-level Shockley-Read-Hall model for carrier recombination and the treatment of trap occupation in terms of quasi-Fermi levels are inadequate for exact analysis. 2) The superlinear dependence of carrier recombination rate on the free-carrier density which can explain the enhancement of photo-induced changes ina-Si∶H under high intensity light. 3) The estimation of capture cross section of the tail states ina-Si∶H. We show that the charged and neutral tail states have rather small capture cross sections of less than 10−16 cm2 and of less than 10−19 cm2, respectively. 4) The effect of the recombination of photogenerated (PG) carriers at the p/i and the n/i interfaces. We estimate the recombination velocityS of PG carriers at these interfaces to be about 103 cm/s. It has been also clarified that the decrease inS is effective to improve the cell performance, especially the open circuit voltage.
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  • 12
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    Applied physics 38 (1985), S. 57-58 
    ISSN: 1432-0630
    Keywords: 72 ; 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The Monte Carlo method has been applied to obtain the average electron velocity at different positions of a submicrometer GaAs channel in the presence of a position independent electric field. Velocity-distance curves are presented for channel lengths of 0.1, 0.2, and 0.5 μm and for lattice temperatures of 300 and 77 K. The curves show significant effects of collisions and boundary conditions.
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  • 13
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    Applied physics 41 (1986), S. 127-135 
    ISSN: 1432-0630
    Keywords: 61.80 ; 72.15 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Atomic mixing of Fe/Al bilayered samples induced by an energetic xenon beam has been studied by RBS-TEM and sheet resistivity measurements. Mixing is detected at 2.5 × 1015 Xe/cm2 and then proceeds up to 2 × 1016 Xe/cm2. A blocking effect of the mixing for larger doses is observed. Homogeneous concentration is not obtained across the sample. Instead a pronounced graded composition is reached. Several explanations of the mixing process and the subsequent blocking effect are suggested: — sharp gradients in the nuclear energy deposition profile which decrease with dose — grain growth phenomena — precipitation of crystalline xenon acting as efficient annihilation sinks for vacancies.
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  • 14
    ISSN: 1432-0630
    Keywords: 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The resistivity increase of very thin metal films during gas adsorption is stronger than predicted by the commond −1 law. This effect is contributed to surface roughness. A quantitative theory is presented which leads to an additionald −3 term. The theory is checked using literature data obtained for the Ag/O2 system.
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  • 15
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    Applied physics 44 (1987), S. 123-130 
    ISSN: 1432-0630
    Keywords: 72.20 ; 61.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Photopyroelectric spectroscopy (P2ES) of n-CdS single crystals was performed at an open circuit, and in conjunction with photocurrent spectroscopy (PCS) in the presence of an applied ac or dc transverse field. The results showed that P2ES is very sensitive to the presence of deliberately introduced subbandgap defect structures, with the P2E signal dominated by non-radiative de-excitation mechanisms at defect centers. The potential of this technique as a powerful electronic defect diagnostic tool, combined with the overall experimental simplicity, was demonstrated with mm-thick crystals used as received in an open-cell geometry.
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  • 16
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    Applied physics 43 (1987), S. 93-95 
    ISSN: 1432-0630
    Keywords: 72.20 ; 73.60 ; 41
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Non-uniform planar resistors are modelled by a small stochastic conductivity pattern superimposed on the constant mean conductivity. At first a theoretical analysis is presented giving the mean square deviation of the resistor current for a given applied voltage. The same problem is then simulated by Monte-Carlo experiments and a good agreement is observed.
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  • 17
    ISSN: 1432-0630
    Keywords: 68.55 ; 68.65 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In addition to the realization of atomically abrupt interfaces in III–V semiconductors by molecular beam epitaxy, the confinement of donor and acceptor impurities to an atomic plane normal to the crystal growth direction, calledδ-doping, is important for the fabrication of artifically layered semiconductor structures. The implementation ofδ-function-like doping profiles by using Si donors and Be acceptors generates V-shaped potential wells in GaAs and AlxGa1−xAs with a quasi-two-dimensional (2D) electron (or hole) gas. In this review we define three areas of fundamental and device aspects associated withδ-doping. (i) The prototype structure ofδ-doping formed by a single atomic plane of Si donors in GaAs allows to study the 2D electron gas by magnetotransport and tunneling experiments, to study the metal-insulator transition, and to study central-cell and multivalley effects. In addition, non-alloyed ohmic contacts to GaAs and GaAs field-effect transistors (δ-FETs) with a buried 2D channel of high carrier density can be fabricated fromδ-doped material. (ii) GaAs sawtooth doping superlattices, consisting of a periodic sequence of alternating n- and p-typeδ-doping layers equally spaced by undoped regions, emit light of high intensity at wavelengths of 0.9 〈λ 〈1.2 [μm], which is attractive for application in photonic devices. The observed carrier transport normal to the layers due to tunneling indicates the feasibility of this superlattice as effective-mass filter. (iii) The confinement of donors (or acceptors) to an atomic (001) plane in selectively doped AlxGa1−xAs/GaAs heterostructures leads to very high mobilities, to high 2D carrier densities, and to a reduction of the undesired persistent photo-conductivity. Theseδ-doped heterostructures are thus important for application in transistors with improved current driving capabilities.
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  • 18
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    Applied physics 46 (1988), S. 249-253 
    ISSN: 1432-0630
    Keywords: 68.55 ; 73.60 ; 77.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The low-temperature fabrication of silicon nitride films by ArF excimer laser irradiation has been studied. Two fabrication methods are presented. One is photo-enhanced direct nitridation of a silicon surface with NH3 for very thin gate insulators, and the other is photo-enhanced deposition of silicon nitride films with Si2H6 and NH3 gases for stable passivation films. The ArF excimer laser irradiation dissociates the NH3 gas producing NH and NH2 radicals which proved effective in instigating the nitridation reaction. The quality of both films has been much improved and the growth temperature has been lowered by using laser irradiation. These photo-enhanced processes seem to be promising ULSI techniques because they do not depend on high temperatures and are free from possible reactor contamination.
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  • 19
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    Applied physics 48 (1989), S. 245-249 
    ISSN: 1432-0630
    Keywords: 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Semiconductor response to ultrafast electric pulses was investigated both theoretically and experimentally. The possibilities for hot-electron drift velocity estimation from a pulsed electric conductivity measurement were analysed. An optoelectronic arrangement with time resolution of 20 ps was used to perform such measurements on then-InSb andn-InAs single crystals. Negative differential mobility (n.d.m.) was observed in both semiconductors at high electric fields.
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  • 20
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    Applied physics 49 (1989), S. 165-169 
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.40 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper is concerned with the optimization of growth conditions for a-Si1-x Ge x :H alloys. It is shown that H-dilution of source gases selectively improves the band transport of electrons without significantly affecting the recombination center density or the band transport of holes. It is further shown that the beneficial effects of H-dilution are most pronounced in alloys with comparable densities of Si and Ge.
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  • 21
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.40 ; 72.80J ; 77.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract ac measurements (1 Hz–10 kHz) have been carried out on a Pb2CrO5 ceramic sample (with surface electrodes) at room temperature as a function of voltage and intensity of visible light illuminating the sample. Cole-Cole complex impedance plots show that the electrical behaviour of Pb2CrO5 is strongly modified when the sample is illuminated. The bulk conductance of the sample is found to increase with increasing light intensity indicating that this dielectric material becomes semiconducting due to the photogeneration of free charge carriers in the conduction band. The dielectric constant of the sample is enhanced by illumination probably due to light-dependent space charge effects in a manner where the dielectric's relaxation time (τ=RC=0.7 ms) remains constant with light intensity. On the other hand, both the bulk conductance and geometrical capacitance of the sample have been found to be almost independent of the applied voltage.
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  • 22
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    Applied physics 36 (1985), S. 183-187 
    ISSN: 1432-0630
    Keywords: 02 ; 72.20 ; 72.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract General formulae are derived to calculate the noise generated by a resistor of arbitrary shape. Contact and bulk noise have been taken into account. By calculating a particular example it will be shown that the influence of the contact and bulk noise can be changed by varying the resistor's shape.
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  • 23
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    Applied physics 43 (1987), S. 47-52 
    ISSN: 1432-0630
    Keywords: 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Cadmium telluride crystals grown by the Travelling Heater Method (THM) technique have been implanted with hydrogen using protons from 2 keV to 3 MeV. Electrical measurements indicate drastic changes in the concentration of defects, especially in the 0.15–0.20 and 0.45–0.60 eV bands. However, the modification induced by hydrogen depends on the starting material, implantation and annealing conditions. Furthermore, resistivity and carrier lifetime are also strongly affected by this treatment.
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  • 24
    ISSN: 1432-0630
    Keywords: 85.30 ; 86.30 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The electrical properties and the degradation behavior of hydrogenated amorphous silicon alloys (a-Si1−x A x : H, with A=C, Ge, B, P) in designs of pin, pip, nin, and MOS structures are investigated by measuring the dark and light I(V) characteristics and the spectral response as well as the space-charge-limited current (SCLC), the time of flight (TOF) of carriers and the field effect (FE). These investigations give an overview of our recent work combined with new results emphasizing the physics of the a-Si:H pin solar cells. We discuss the stabilizing influence on the degradation behavior achieved by profiling the i layers of the pin solar cells with P and B. Two kinds of pin solar cells, namely glass/SnO2/p(C)in/metal and glass/metal/pin/ITO, are investigated and an explanation of their different spectral response behavior is given. SCLC measurements lead to the conclusion that trapping is also involved in the degradation mechanism, as is recombination. TOF experiments on a-Si1−x Ge x : H pin diodes indicate that the incorporation of Ge widens the tail-state distribution below the conduction band. FE measurements showed densities of gap states of about 5×l016cm−3eV−1.
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  • 25
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.80J ; 70.90
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An ac impedance method has been used to study the electrical properties of an illuminated HgI2 crystal as a function of temperature [10–350 K] and frequency [1–104 Hz]. The complex impedance plane plots enabled us to determine the bulk resistance of the crystal as a function of temperature. Activation energies of [0.08±0.005 eV] and [0.25 ±0.01eV] are then found; they are attributed to acceptor and donor trapping levels, respectively. At temperatures lower than 230 K, a weak temperature dependence of the bulk resistance is observed. This weak dependence is supposed to be due to photoconductivity.
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  • 26
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    Applied physics 36 (1985), S. 63-65 
    ISSN: 1432-0630
    Keywords: 66 ; 72.20 ; 77.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The dielectric properties of titanium-doped magnesium oxide (Ti/MgO) and nickel-doped magnesium oxide (Ni/MgO) single crystals have been measured in the range of temperature from 300 to 450 K at the microwave frequency of 9.31 GHz. For both crystals the dielectric properties are found similar. From the conductivity data, the activation energy in the measured temperature region has been estimated to be 0.15 eV. The values of the temperature dependence (ε′−1)−1(ε′+2)−1 (∂ε′/∂T) p have been calculated. The data confirms the Bosmann and Havinga postulate that, for materials in which the dielectric constant;ε′ is less than 20 the temperature dependence should be positive.
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  • 27
    ISSN: 1432-0630
    Keywords: 68.55 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract H2S gas has been used during molecular beam epitaxy (MBE) growth of GaAs and Al x Ga1−x As as sulphur vector forn-type doping. Doping efficiencies are less than 10−3 at usual growth temperatures, and are limited by an incorporation competitive surface process, probably 2Ga+H2S→Ga2S+H2. In AlxGa1−x As forx≧0.2 the doping efficiency is further reduced by carrier freeze-out at deep levels. Measured thermal activation energies depend on growth conditions and remain relatively low even up to the direct-indirect bandgap crossover for substrate temperatures in the 585–645
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  • 28
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    Applied physics 46 (1988), S. 255-273 
    ISSN: 1432-0630
    Keywords: 73.60 ; 77.50 ; 81.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper presents an overview of the single-wafer optical processing techniques for integrated circuit fabrication with an emphasis on their applications to insulator growth. Rapid thermal growth of various thin homogeneous and heterogeneous dielectrics on silicon substrates including silicon dioxide, silicon nitride, nitrided oxides, and composition-tailored insulators will be described and some electronic device applications of the rapidly grown dielectrics will be examined. Multicycle rapid growth processes have been used for dielectric structural engineering and in-situ formation of thin layered insulators. The compositional depth profiles and the electrical characteristics of devices are controlled through the synthesis of an appropriate sequence of the wafer temperature-vs-time profiles and process gas cycles. The ongoing developments and future prospects of single-wafer rapid processing for advanced microelectronics manufacturing will also be discussed.
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  • 29
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    Applied physics 46 (1988), S. 5-8 
    ISSN: 1432-0630
    Keywords: 73.60 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Measurements of steady-state photoconductivity with respect to light-induced defect generation in amorphous hydrogenated silicon (a-Si: H) show that the power index of the time evolution (long-term observation) of the photodegradation is determined by the exposure temperature and the material.
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  • 30
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    Applied physics 47 (1988), S. 123-129 
    ISSN: 1432-0630
    Keywords: 81.10 ; 73.60 ; 75.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Capacitance-voltage (CV) profiling measurements on delta-doped n-type GaAs reveal extremely narrow peaks with a full-width at half-maximum of 40 Å. Comparison of experimental with self-consistently calculated CV profiles demonstrates that Si impurities are localized on a length scale of a lattice constant in delta-doped GaAs. Diffusion and segregation are of minor importance. The basic theory of CV measurements on quantummechanical systems such as delta-doped semiconductors is developed and presented.
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  • 31
    ISSN: 1432-0630
    Keywords: 73.60 ; 75.60 ; 68.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have grown by means of Molecular Beam Epitaxy ultrathin (1 to ∼ 10 ML) films of fcc Fe and Co on a Cu(001) surface, thus stabilizing this high temperature phase of bulk Fe and Co at room temperature. All films, including the single monolayers, are ferromagnetic. The Co films are magnetized in plane, independently on the thickness. Fe films thicker than 2 ML are magnetized along the film normal. Up to now, the statistical uncertainty is still too large to conclusively prove an enhancement of the magnetic moment for the thinnest Co films.
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  • 32
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    Applied physics 47 (1988), S. 205-208 
    ISSN: 1432-0630
    Keywords: 74.70 ; 72.20 ; 61.70
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Thermoelectric power (TP) and electrical conductivity (EC) measurements were performed for YEa2Cu3Ox at 1128 K under controlled oxygen partial pressure varying between 50 and 105 Pa. Three regimes are observed for the electrical properties. At low $$p_{{\text{O}}_{\text{2}} } (〈 1.6{\text{ }} \times {\text{ 10}}^{\text{2}} {\text{ }}{\text{Pa}})$$ both TP and EC remain constant with $$p_{{\text{O}}_{\text{2}} } $$ . In the medium range $$(1.6{\text{ }} \times {\text{ 10}}^{\text{2}}〈 p_{{\text{O}}_{\text{2}} }〈 7.6{\text{ }} \times {\text{ 10}}^{\text{3}} {\text{ Pa)}}$$ sharp changes of both electrical parameters occur; TP changes sign from positive above 4×102 Pa to negative below this $$p_{{\text{O}}_{\text{2}} } $$ value. In the high $$p_{{\text{O}}_{\text{2}} } $$ region (〉7.6×103 Pa) TP vs log $$p_{{\text{O}}_{\text{2}} } $$ exhibits two slopes; 5.1 below 1.5×104 Pa and 8.4 above this $$p_{{\text{O}}_{\text{2}} } $$ value. The slopes can be discussed in terms of the defect structure involving singly and doubly ionized oxygen vacancies below and above 7.6×103 Pa, respectively.
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  • 33
    ISSN: 1432-0630
    Keywords: 72.20
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Measurements of the electrical conductivity, thermelectric power and thermal conductivity of an AgTlTe2 semiconductor in the solid and liquid states were carried out in a wide range of temperatures. In the liquid state the data analyzed in terms of a model developed for the density of states and electrical transport in solid amorphous semiconductors. Positive thermoelectric power suggests a large predominance of holes in electrical transport.
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  • 34
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    Applied physics 48 (1989), S. 549-558 
    ISSN: 1432-0630
    Keywords: 79.60 ; 73.40 ; 73.60 ; 73.60H ; 71.25M ; 81.15 ; 46.30P
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The interface properties of hydrogenated amorphous carbon films (a-C:H) on Si and GaAs substrates have been studied by in-situ photoelectron spectroscopy measurements. The a-C:H films have been deposited by direct ion beam deposition. Distinct differences in the interface formation have been observed during film depositon on the two substrates. The data clearly reveal a decomposition of the GaAs at the interface which can be related to the reduced adhesion of a-C: H on the compound semiconductor substrate.
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  • 35
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    Applied physics 49 (1989), S. 431-436 
    ISSN: 1432-0630
    Keywords: 71.55 ; 66.30 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recent investigations on transition-metal impurities in silicon emphasizing the effect of the combined diffusion of two transition metals are presented and briefly discussed. The electronic properties and basic thermal kinetics are analysed by DLTS. The conversion of a Pd-related multivalent defect atE c-0.35 eV andE c-0.57 eV to the Pd-related defect atE c −0.22 eV is observed, and a Pd-Fe complex level atE c −0.32 eV is identified. The annealing characteristics of the multivalent Rh levels atE c-0.33 eV andE c-0.57 eV are observed, and used to analyse the influence of prior Rh doping on the Au diffusion. A complex formed by the codiffusion of Au and Cu is observed atE v+0.32eV andE v+0.42 eV, and shown to exhibit bistable behavior as does a similarly produced Au-Ni complex observed atE v + 0.35 eV andE v+0.48 eV.
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  • 36
    ISSN: 1432-0630
    Keywords: 73.60 ; 72.40 ; 78.20
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    Notes: Abstract Amorphous Si1−xCx: H thin films were prepared by the rf magnetron sputtering method using a composite target of silicon and graphite. The dependence of the optical, structural, electrical, and optoelectronic properties on the carbon contentx was investigated, by measuring the optical absorption spectra, ir spectra, dark conductivity, photoconductivity and ESCA spectra. The optical gap was found to be unchanged with increasingx below about 0.6, in spite of the increase in the amount of the SiC bond. This is considered to be due to the formation of the carbon clusters. It is found that the photosensitivity shows a maximum at aboutx = 0.2, and is about one order of magnitude larger than the film withx = 0. This is related to the decrease in the dark conductivity, which is ascribed both to the formation of the SiC bond and to the reorganization of the defect-rich structure of sputter-deposited amorphous Si by the addition of about 20% carbon. The photoconductive effect was gradually lost in the range ofx above 0.6. In this range, the optical gap increases rapidly owing to the rapid increase of the SiC bond.
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  • 37
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    Applied physics 38 (1985), S. 145-149 
    ISSN: 1432-0630
    Keywords: 72.20
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The impact ionization in p-type indium antimonide at 77 K was investigated both experimentally and theoretically. The dc pulse measurements with the time resolution of 50 ps and the high-field Hall measurements produced clear evidence that the impact ionization inp-InSb is initiated by equilibrium holes. The calculated hole generation rate gives good agreement with the experimental results.
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  • 38
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    Applied physics 39 (1986), S. 135-139 
    ISSN: 1432-0630
    Keywords: 72.20
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    Notes: Abstract Coherent current oscillations with frequencies of several hundreds of megahertz and microwave generation at frequencies up to 40 GHz were investigated in then-InSb samples subjected to crossed electric and magnetic fields. They are shown as being caused by electric field redistribution and negative differential mobility in high-field regions.
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  • 39
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    Applied physics 40 (1986), S. 171-176 
    ISSN: 1432-0630
    Keywords: 73.60 ; 71.20 ; 86.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have reexamined the validity of quasi-static capacitance-voltage (C-V) measurements when applied to hydrogenated amorphous silicon (a-Si: H) diodes. Displacement currents with the application of a linear ramp voltage to an a-Si:H Schottky diode exhibit a slow response with time constants ranging 0.1–1 s which cannot be measured completely by the conventional measurements. The measured capacitance and the effective density of gap states obtained from the measurement depend on the timing of current observation even when the small value of the order of 0.01 V/s is chosen for the ramp rate. We propose a possible means to realize the true quasi-staticC-V measurement of a-Si:H diodes.
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  • 40
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    Applied physics 42 (1987), S. 303-309 
    ISSN: 1432-0630
    Keywords: 72.20 ; 79.20 ; 85.30
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Large signal characterisation of double heterostructure DDR Impatt diode has been carried out in the millimeter-wave range considering the MITATT mode of operation. The structure of the device is p+-p2-p1-n1-n2-n+ where impact ionisation and tunneling takes place in the p1-n1 region. In this study we have considered two well-known heterostructures, e.g., InP/GaInAs/InP and InP/InGaAsP/InP and one nonconventional structure GaAs/InP/GaAs. The theoretical results of the performances of these devices as regards of output power, efficiency, and negative conductance revealed that the structures are quite promising as the source of power in the millimeter-wave range. The analysis may be used for other mm wave DDR heterostructure Impatts.
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  • 41
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    Applied physics 43 (1987), S. 29-35 
    ISSN: 1432-0630
    Keywords: 71 ; 72.20 ; 78
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    Notes: Abstract The pre-exponential factor of the transition probability of a trapped charge carrier into an excited state is evaluated from two different approaches. The semi-classical treatment based on a thermodynamical concept involves the calculation of the vibrational entropy change from the partition sum. The quantum-mechanical treatment deals with non-radiative transitions due to electron-phonon coupling. The factor is found to be explicitely dependent on both the temperature and the lattice vibration frequencies represented by a single Einstein oscillator. In addition, the results from different concepts show similar behaviour. As a consequence the effect of lattice vibrations on the position as well as on the shape of glow peaks in thermally stimulated measurements are investigated on a simple phenomenological base. The analysis of some experimental results can be performed in accordance with the theoretical predictions.
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  • 42
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    Keywords: 72.20 ; 72.80J ; 70.90
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    Notes: Abstract The real part of the dielectric constant was studied in the temperature range of 340 to 10 K, and at frequencies that range from 1 to 104 Hz. The dipole contribution to the dielectric constant has been found at temperatures lower than 110 K while the space-charge contribution due to the increase of crystal defects is dominant at temperatures higher than 290K.
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  • 43
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    Applied physics 43 (1987), S. 139-141 
    ISSN: 1432-0630
    Keywords: 85.40 ; 72.20 ; 76
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A polarized N-O bond behaves as an intramolecular p-n junction. Their rectifying properties have been found in 1,3-dimethylisoxasole, 1-phenylsydnone, and 1-(4-methylphenyl)sydnone molecules based on H1-NMR data.
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  • 44
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    Applied physics 44 (1987), S. 279-284 
    ISSN: 1432-0630
    Keywords: 81.40 ; 72.20
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The behaviour of Xe implanted at the Ni-Si interface and irradiated with Nd-laser pulses is studied in details and compared with Xe implantation into NiSi2 and into pure Si. Ion beam mixing followed by laser irradiation is able to form good quality epitaxial NiSi2 layer on Si. An inward segregation of Xe is observed with retention of Xe at a depth of 30 nm inside pure silicon. Implantation of Xe into NiSi2 or pure Si causes broadening and loss of Xe, as generally observed for implantation into pure materials. The different behaviour of Xe at the Si/NiSi2 interface must thus be ascribed to peculiar characteristics of the interface itself.
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  • 45
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    Applied physics 46 (1988), S. 113-117 
    ISSN: 1432-0630
    Keywords: 72.20
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    Notes: Abstract Switching effects in AgTlSe2 and CuTlSe2 chalcopyrite semiconductors films have been investigated. The threshold switching voltage was found to increase linearly with the thickness, moreoverV th increases exponentially with the temperature. The rapid transition between the highly resistive and conductive states was attributed to an electrothermal origin from Joule's heating of a current channel.
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  • 46
    ISSN: 1432-0630
    Keywords: 61.40 ; 72.20 ; 78.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Films of a-Si: H have been deposited by means of a dc hot cathode discharge of SiH4 with electrostatic confinement at a pressure as low as 0.4 Pa. The plasma used is quite quiescent as has been observed by means of reproducible Langmuir probe measurements. Substrates have been placed at different locations in between the electrodes, some of them facing the anode and the others facing the cathode. Films deposited on substrates facing the cathode present a granular, non-columnar, structure, an IR spectrum with only SiH absorption peaks, and a very low photoresponse. Films deposited on substrates facing the anode have a similar IR spectrum but are homogeneous, have lower hydrogen content, and present a high photoresponse. The optical absorption coefficientα shows in all samples theαnE=C(E−E0) x behaviour, but with exponentx=3 and notx=2 as is usually considered in a-Si∶H.
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  • 47
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    Applied physics 46 (1988), S. 249-253 
    ISSN: 1432-0630
    Keywords: 68.55 ; 73.60 ; 77.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The low-temperature fabrication of silicon nitride films by ArF excimer laser irradiation has been studied. Two fabrication methods are presented. One is photoenhanced direct nitridation of a silicon surface with NH3 for very thin gate insulators, and the other is photo-enhanced deposition of silicon nitride films with Si2H6 and NH3 gases for stable passivation films. The ArF excimer laser irradiation dissociates the NH3 gas producing NH and NH2 radicals which proved effective in instigating the nitridation reaction. The quality of both films has been much improved and the growth temperature has been lowered by using laser irradiation. These photo-enhanced processes seem to be promising ULSI techniques because they do not depend on high temperatures and are free from possible reactor contamination.
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  • 48
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    Applied physics 46 (1988), S. 255-273 
    ISSN: 1432-0630
    Keywords: 73.60 ; 77.50 ; 81.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper presents an overview of the single-wafer optical processing techniques for integrated circuit fabrication with an emphasis on their applications to insulator growth. Rapid thermal growth of various thin homogeneous and heterogeneous dielectrics on silicon substrates including silicon dioxide, silicon nitride, nitrided oxides, and composition-tailored insulators will be described and some electronic device applications of the rapidly grown dielectrics will be examined. Multicycle rapid growth processes have been used for dielectric structural engineering and in-situ formation of thin layered insulators. The compositional depth profiles and the electrical characteristics of devices are controlled through the synthesis of an appropriate sequence of the wafer temperature-vs-time profiles and process gas cycles. The ongoing developments and future prospects of single-wafer rapid processing for advanced microelectronics manufacturing will also be discussed.
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  • 49
    ISSN: 1432-0630
    Keywords: 72.20
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The nonlinearI–V behaviour and threshold switching of the bulk Se-Te-Sn system have been experimentally studied at various temperatures. It is observed that the curves are linear for low voltages and become superlinear at higher voltages. After a certain voltageV th, the current through the material shoots to a very high value and the potential across the material drops to a low value. It is also found that there is a decrease inV th with increase in percentage of tin and temperature. An attempt is made to explain the nonlinearI–V behaviour and threshold switching on the basis of a microcrystallite model. A study of Se-Te-Sn system reveals that our results are in concurrence with the theoretical predictions.
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  • 50
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    Applied physics 48 (1989), S. 181-188 
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.70 ; 06
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    Notes: Abstract A method for quantitative characterization of chaotic dynamical systems is discussed. An electronic instrument for determining the number of independent variablesk *, involved in the motion, is described. It allows one to obtain these in real time from a single observable. The suggested technique has been applied to quantification of strange attractors underlying chaotic instabilities in semi-insulating GaAs∶Cr, and n-Ge, irradiated with high energy electrons. In n-Ge, for instance, the measured numbersk * range from 2 to 4 depending on control parameters. These measurements reveal the highly deterministic nature of the observed chaotic oscillations. The physical mechanisms responsible for the current instabilities and chaotic behaviour are discussed.
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    Applied physics 49 (1989), S. 273-277 
    ISSN: 1432-0630
    Keywords: 73.60
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Metallic superlattices of copper and manganese have been synthesized on glass and mica substrates by a sequential evaporation technique. The electrical resistivity and the temperature coefficient of resistance (TCR) of layered Cu/Mn has been studied for various thicknesses (d) in the range 2–6 nm by varying the number of double layers (n) from 5–35. The transition from a negative to positive TCR has been observed ford 〉5 nm. The thickness dependence of room temperature resistivity (ϱ RT) and TCR shows oscillatory behaviour.
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  • 52
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    Angewandte Makromolekulare Chemie 150 (1987), S. 189-192 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A morphological study was made to examine the friction and wear mechanisms of ultrahigh molecular weight polyethylene in air and water by means of transmission electron microscopy of a carbon replica film of a very thin layer of the polymer surface slid against a steel ball. Electron diffractions revealed that a molecular orientation with a typical fiber pattern was formed in the friction in air, while thin ribbon-like crystals with particular crystal orientations were formed in water in a way that the sliding took place on the crystallographic a - c plane, giving rise to a low friction coefficient of the polymer.
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  • 53
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    Angewandte Makromolekulare Chemie 150 (1987), S. 137-150 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde der relative Wirkungsgrad von fünf handelsüblichen Stabilisatoren bei Photooxidation und thermischer Alterung von Polypropylen (PP) anhand der Änderungen der mechanischen Eigenschaften untersucht. Es wurden Polypropylenproben mit unterschiedlichem Anteil an Cyasorb UV-531 hergestellt (bezeichnet als PC0.5-31, PC1-31, PC1.5-31 und PC2-31). Der Einfluß der Photooxidation auf das thermische Verhalten ist mit Hilfe der Differentialscanningkalorimetrie und durch thermogravimetrische Analysen untersucht worden. 2-Hydroxy-4-n-octyloxybenzophenon (2 Gew.-%) war am wirksamsten, Polypropylen, gegen Verfärbung und Brüchigkeit zu stabilisieren. Bei einer Probe mit 1% Stabilisatorzusatz fanden sich nach 32 h Bestrahlung noch 81% des ursprünglichen Wertes der Streckgrenze gegenüber 18% bei unstabilisiertem PP.
    Notes: The relative effectiveness of five commercially available stabilizers on the photooxidation and thermal ageing of polypropylene (PP) was investigated by following changes in mechanical properties. Samples of PP containing different percentages of Cyasorb UV-531 were prepared (designated as PC0.5-31, PC1-31, PC1.5-31, and PC2-31, respectively). The effect of photooxidation on thermal behaviour was investigated by differential scanning calorimetry and thermogravimetric analysis. 2-Hydroxy-4-n-octyloxy benzophenone (2% w/w) was most effective in stabilizing PP towards discolouration and brittleness. After 32 h irradiation, 81% retention in yield strength was observed in case of PC1-31 against 18% in case of PP.
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  • 54
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of the nature of the polyols used in polyurethane (PUR) synthesis on the structural transformations after ageing by UV irradiation has been studied. The investigations were performed on PUR prepared from polyester and polyether diol oligomers.The characterization of the samples before and after ageing in view of the structural changes, which influence the course of the photooxidative degradation and photocrosslinking as well as in view of changes of mechanical properties has been done. Comparative investigations were performed by spectroscopic and viscometric measurements.The results show pronounced heterogeneity of the degradative reactions, including the existence of crosslinking processes and producing thus very inhomogeneous polymeric material. The course and the intensity of photooxidative degradation of PUR differ together with changes of mechanical properties depending whether polyester or polyether polyol have been used. The processes of photooxidative degradation is less expressed in polyesterurethane then in polyurethane based on polyether, under the same conditions of experiments. Different structures of polyester diols caused the various ageing behaviour of PUR too.
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  • 55
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: QUALIFICATION OF HALS COMPOUNDSA complex method of examination has been developed suitable for the qualification of light stabilizers; by this method, according to experience, the efficacy of HALS compounds can be extensively and expediently characterized.Several light stabilizers of the HALS-type were examined and qualified, used alone or together with a UV-absorber.It has been found that, when selecting the appropriate structure for a given polymer, the weatherability of polyolefine foils is effectively increase to six-eightfold; the increase is even tenfold when the stabilizer is combined with a benzophenone-type compound.As a utilization of these experiences, a contract with the industry, led to the production of an LDPE based agricultural foil with a life-time of several years.
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  • 56
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Natural hail impact tests are scarcely available because hailstorms are limited to a small area and cannot be predicted regarding time, place and intensity. Therefore we relied on laboratory tests simulating natural hailstones by polyamide balls (5-50 mm dia.) whose final velocity could be varied according to meteorological data. So the influence of diameter (weight) and velocity of the artificial hailstones could be taken into consideration independently.The energy of damage or equivalent natural hailstone diameter were determined for 16 mm double skin sheet from PMMA as 0.2 J (14 mm dia.) for star shaped cracks and 2 J (26 mm dia.) for holes. These values do not significantly decrease after 10 years weathering. 10 mm double skin sheets from PC show an extremly high energy of damage of abt. 10 J (38 mm dia.) which decreases to a medium level of 2 J (26 mm dia.) after several years weathering. This decrease is remarkably reduced by weather resistant protective coating.As hailstorms consist to more than 80% of hailstones below 10 mm dia. (0.04 J) the mentioned sheet materials are quite hail resistant also after long weathering periods, but they cannot withstand an extreme hail catastrophe as in Munich July 12, 1984.
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  • 57
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the specimen temperature on many ageing processes is well known. Two aspects is dealt with: -Measurements of the specimen temperature on several positions of a specimen in commercial weathering devices at different exposure conditions. Technical measures to achieve to uniform ageing at all positions of a planar and homogeneous specimen. Examples from practical use.-Changing specimen temperatures (+60°C to -20°C) during the course of accelerated weathering, i.e. a combination of conventional accelerated weathering with a temperature cycle test.
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: An Folien (Dicke 100 pm) aus isotaktischem Polypropylen mit verschiedenen Antioxidansgehalten (0,0% bis 0,1%) wird die thermooxidative Alterunq mit der isothermen Langzeit-Differential-Thermo-Analyse (ILDTA) bis zu Temperaturen weit unter dem Kristallitschmelzbereich verfolqt und die Messwerte mit Ergebnissen aus dem Zeitstand-Zugversuch korreliert. Dabei zeigt sich, daß aus Messunqen mit der ILDTA bereits vor Einsetzen der autokatalytischen Zersetzunq sreaktion Ruckschlüsse auf die thermische Vorqeschichte der Proben und Aussagen auf das rnit einem Abfall der mechanischen Eigenschaften verbundene Ende der thermo-oxidativen Stabilität des Polymeren getroffen werden können.Weiters bietet die ILDTA die Moglichkeit, durch den direkten Zusamenhang zwischen Oxidationszeit und Antioxidansögehalt die örtliche Stabilisatorverteilung in Platten und in Folien zu bestimmen und damit Diffusionsvorqange zu verfolgen.
    Notes: Thermo-oxidative ageing processes were investigated in films (100 μm thick) made from isotactic polypropylene with different antioxidant concentrations between 0% and 0.1% using isothermal long-term differential thermal analysis (ILDTA). The end of the oven life of polypropylene coincided with the loss of mechanical properties which was confirmed by tensile tests at temperatures far below the crystallite melting range. Already prior to the beginning of autocatalytic decomposition, ILDTA experiments permits conclusions to be drawn on the thermal history of the specimens and statements made regarding the end of thermo-oxidative stability of the polymer, which is accompanied by a deterioration in the mechanical properties.In consequence of the correlation between oxidation time and antioxidant concentration the local antioxidant concentration in sheets or films can be measured by ILDTA. Thus, investigating the diffusion of an antioxidant in polypropylene using ILDTA is possible.
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  • 59
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Größenverteilungsfunktion von Dispersionen mit extrem breiter Verteilung (Durchmesserbereich 20 〈 D 〈 2000 nm) kann in der analytischen Ultrazentrifuge (AUC) nicht durch eine Standardmethode, z. B. durch Messung der Trübung τ bei einer einzigen Konzentration, bestimmt werden, weil sich die spezifische Trübung τ/c von sehr kleinen und sehr großen Teilchen zu stark unterscheidet. Um dieses Problem zu lösen, haben wir eine neue AUC-Technik, die sogenannte Coupling-PSD-Technik entwickelt. Dabei werden zwei unterschiedliche Konzentrationen derselben Dispersion gleichzeitig in einem einzigen AUC-Lauf vermessen und zwei korrespondierende Lichtintensitiit-Zeit-Kurven aufgezeichnet. Bei einer niedrigen Standardkonzentration cs werden hauptsachlich die größeren Teilchen erfaßt während bei einer 5 bis 30 mal heheren Konzentration ch vor allem die kleineren Teilchen registriert werden. Die beiden I(t)-Kurven werden mathematisch verkniipft und unter Verwendung des Stokeschen Gesetzes und der Streutheorie von Mie für homogene isotrope Kugeln in die gesuchte breite Verteilungsfunktion umgerechnet. Wir benutzen eine mit einem 8-Zellen-Rotor und einem Multiplexer ausgestattete AUC. Da sehr groBe und sehr kleine Teilchen gleichzeitig in einem einzigen Zentrifugenlauf bestimmt werden, kennen wir nicht mehr wie zuvor eine konstante Rotorgeschwindigkeit N anwenden, sondern miissen diese mit Hilfe eines Geschwindigkeitsprogramms N(t) innerhalb einer Stunde von 0 auf 40000 U/min erhehen.
    Notes: The particle size distribution (PSD) of extremely broad distributed dispersions (diameter range 20 〈 D 〈 2000 nm) is not possible to be measured by analytical ultracentrifuge (AUC) using the standard technique, i.e. measuring turbidity τ at a single concentration c, because the specific turbidity τ/c varies too much between very small and very large particles. To solve this problem we have developed a new AUC technique, the so-called Coupling-PSD-Technique. Here two different concentrations of the same dispersion are measured simultaneously by one single AUC run with two corresponding curves of light intensity I vs. time t being registered. At a low standard concentration cs, mainly the larger particles are detected, while at a concentration ch 5 to 30 times higher mainly the smaller particles are registered. Both I(t)-curves are coupled mathematically and transformed into the requested broad distribution curve employing Stokes' law and Mie's light scattering theory for homogeneous isotropic spheres.We use an AUC together with an 8-cells-rotor and a multiplexer. Because very large and very small particles are to be measured simultaneously in one single run, we can no more apply a constant rotor speed N as before, but by means of a time program N(t) we always have to increase the rotor speed from 0 to 40000 rpm within one hour.
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  • 60
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    Angewandte Makromolekulare Chemie 162 (1988), S. 135-148 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die chemische Modifizierung von Polyvinylchlorid (PVC) durch ein Amin verleiht dem Polymeren höhere Reaktivität gegenüber der Pfropfcopolymerisation mit einem Vinylmonomeren. Die Pfropfcopolymerisation von Methylmethacrylat auf mit n-Butylamin modifiziertes PVC wurde thermisch mit Benzoylperoxid (Bz2O2) als Initiator oder photoaktiviert mit Benzophenon (BP) als Photosensibilisator gestartet. Das aus bestimmten Experimenten erhaltene rohe Polymerprodukt wurde durch fraktionierte Fällung in die verschiedenen Bestandteile wie Polymethylmethacrylat (PMMA, Homopolymeres), PVC-g-PMMA (Pfropfcopolymeres) und unverändertes (aminiertes) PVC aufgespalten. Die getrennten Fraktionen wurden mit Hilfe der IR-Spektroskopie und der Thermogravimetrie charakterisiert. Der Mechanismus der Pfropfcopolymerisation von den beiden verschiedenen Systemen wurde erörtert. In beiden Fällen wurden Pfropfausbeuten um 30 - 70%* und Pfropfcopolymerzusammensetzungen, PMMA/PVC (w/w) zwischen 2 und 3 erhalten.
    Notes: Chemical modification of poly(vinyl chloride), PVC, by an amine renders the polymer more reactive towards graft copolymerization with a vinyl monomer. The graft copolymerization of methyl methacrylate (MMA) on PVC modified by treatment with n-butylamine (n-BA) was started thermally at 30° using benzoyl peroxide (Bz2O2) as initiator and under photoactivation at 40° using benzophenone (BP) as photo sensitizer. The gross polymer products from selected experiments were fractionally separated into the constituent polymeric entities viz., poly(methyl methacrylate), PMMA (homopolymer), PVC-g-PMMA (graft copolymer), and unreacted (aminated) PVC following a method of fractional precipitation. The separated fractions were characterized by IR spectroscopy and thermogravimetry. The mechanisms of graft copolymerization for the two different systems have been discussed. In each case, grafting efficiencies of the order of 30-70% and graft copolymers having compositions given as PMMA/PVC (w/w) equal to 2-3 were readily obtained.
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  • 61
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    Angewandte Makromolekulare Chemie 162 (1988), S. 193-201 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe oberflächensulfonierter, makroporöser Styrol-Divinylbenzol-Copolymerer mit unterschiedlichen Gehalten an SO3H-Gruppen wurden hergestellt. Sowohl von diesen Copolymeren als auch vom nichtsulfonierten Copolymeren wurden Porenstruktur, Oberflächenhydrophilie und -polarität sowie das Sorptionsverhalten gegenüber einigen in Blut vorkommenden Substanzen bestimmt. Der Sorptionsgrad wird umso kleiner, je größer die Oberflächenpolarität ist. Die teilsulfonierten Polymeren könnten eine Anwendung in der Hämoperfusion finden.
    Notes: A series of surface sulphonated macroporous styrene-divinylbenzene (S-DVB) copolymers containing various amounts of  - SO3H groups was obtained. Porous structure, surface hydrophilicity and polarity, and sorption properties of these copolymers as well as those of starting S-DVB resin towards some substances which are present in blood were determined. The sorption degree becomes the smaller the higher is the surface polarity. The partially sulphonated copolymers may find an application in hemoperfusion.
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  • 62
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß einer chemischen Behandlung von dünnen Filmen einer Composit-Membran aus sulfoniertem Polyphenylenoxid wurde untersucht. Über den Einfluß der Konzentration von wáßrigen Lösungen von Formaldehyd, Schwefelsäure, Salzsäure, Phosporsäure, Natriumhydroxid sowie der Behandlungsdauer auf die Trenncharakteristik der inversen Osmose der Composit-Membranen mit einer Ionenaus-tauschkapazität von 2,14 und 2,50 meq/g in verschiedenen Kombinationen wird ausführlich berichtet. Die Ergebnisse zeigen, daß unter den besten chemischen Behandlungsbedingungen eine Erhöhung der Trenncharakteristik der inversen Osmose der sulfonierten Polyphenylenoxid/Polysulfon-Composit-Membran erreicht wird.
    Notes: The effect of chemical treatment on the reverse osmosis (RO) separation characteristics of sulfonated poly(phenylene oxide) (SPPO) thin film composite membranes was investigated. The effects of the concentrations of aqueous solutions of formaldehyde, sulfuric acid, hydrochloric acid, phosphoric acid, sodium hydroxide, and treatment time on the RO separation characteristics of the composite membranes with ion exchange capacity (IEC) of 2.14 and 2.50 meq/g in various combinations are reported in detail. The results indicate some enhancement in RO separation characteristics of the SPPO/polysulfone (PS) composite membrane under the best conditions of the chemical treatment.
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  • 63
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der Herstellung dünner Filme von sulfonierten Polyphenylenoxid/Polysulfon (SPPO/PS)-Composit-Membranen wurde untersucht, daß ein Zusatz von Nitromethan zu einer Lösung von sulfoniertem Polyphenylenoxidnatrium erhöhte Wirkung auf die Trenncharakteristik der inversen Osmose besitzt. Der Einfluß von gamma-Strahlung auf dünne Filme der Composit-Membran unter nassen und trockenen Bedingungen wurde ebenfalls untersucht. Um die maximal mögliche Verbesserung zu erreichen, wurden die Composit-Membranen einer kombinierten chemischen und Gammastrahlen-Behandlung unter nassen und trockenen Bedingungen unterworfen.Die experimentellen Ergebnisse dieser kombinierten Behandlung zeigen, dalß die SPPO/PS Composit-Membran dabei abgebaut wird.
    Notes: The enhancement effect of the addition of nitromethane into the coating solution of sulfonated sodium poly(phenylene oxide) (SPPONa) polymer for the synthesis of sulfonated poly(phenylene oxide)/polysulfone (SPPO/PS) thin film composite membranes on reverse osmosis (RO) separation characteristic was studied. The effect of gamma-ray irradiation on the SPPO/PS thin film composite membranes was also evaluated when the membrane samples were in the wet and dry conditions. The composite membranes were also subjected to a chemical treatment combined with gamma-ray irradiation in both wet and dry conditions in the hope of obtaining the maximum possible enhancement under each treatment. However, the experimental data of this combined treatment indicated the possibility of some degradation of the SPPO/PS composite membranes.
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  • 64
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    Angewandte Makromolekulare Chemie 163 (1988), S. 37-45 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mischungen aus Poly(styrol-co-butadien)/Polybutadien, Naturkautschuk/Poly-(ethylen-co-propylen-co-dien und Naturkautschuk/Poly(butadien-co-acrylnitril)) wurden nach drei unterschiedlichen Verfahren compoundiert und Härtungsverhalten sowie Zugfestigkeit und Bruchdehnung der Vulkanisate wurden verglichen.
    Notes: Compounding of styrene-butadiene copolymer/polybutadiene, natural rubber/ethylene-propylene-diene terpolymer and natural rubber/butadiene-acrylonitrile copolymer blends was done in three different ways and their curing behaviour and the tensile properties of the vulcanizates are compared.
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  • 65
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Methylmethacrylat (MMA) wurde mit Hilfe von Cerammoniumnitrat als Initiator auf Stärke gepfropft. Die Pfropfcopolymeren wurden durch selektive Lösungsextraktion in einem Soxhlet-Extraktor isoliert. Der Einfluß von Reaktionszeit, Initiatorkonzentration, Temperatur sowie der Monomer- und Särekonzentration auf die Pfropfausbeute wurde untersucht. Eine erste Studie der Kinetik dieser Pfropfcopolymerisationsreaktion zeigt, daß sie dem üblichen kinetischen Verhalten einer Radikalpolymerisation folgt.
    Notes: Methyl methacrylate (MMA) was grafted onto starch using ceric ammonium nitrate as initiator. The graft copolymers were isolated by selective solvent extraction in a Soxhlet apparatus. The effects of reaction time, initiator concentration, temperature, monomer, and acid concentrations on the graft yields were investigated. A preliminary kinetic study of the graft copolymerisation reactions shows that they follow the conventional kinetic behaviour of free radical polymerisation.
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  • 66
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    Angewandte Makromolekulare Chemie 163 (1988), S. 47-61 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Verwendung von Phenol-Formaldehyd-Harz mit gepreßten Olivenkenen im Gewichtsverháltnis 20/80 wurden kleine zylindrische Formkörper durch Härtung hergestellt. Diese wurden pyrolysiert und einige Proben mit Wasserdampf aktiviert. Für diese Formkörper und für zwei kommerzielle Aktivkohlen für Laboratoriumsbzw. Industrie-Anwendungen wurden folgende Eigenschaften bestimmt: die spezifische Oberfláche, die Struktur, die Adsorptionseigenschaften sowie die Adsorptionskapazität. Die Ergebnisse zeigen, daß die hergestellten kohlenstoffhaltigen Materialien durch Aktivierung höhere Werte für die untersuchten Eigenschaften ergeben als die nur pyrolysierten Proben und die zwei kommerziellen Aktivkohlen. Es wurde festgestellt, daß die Adsorption des 4-Nitrophenols für alle untersuchten kohlenstoffhaltigen Materialien gemäß der Freundlich-Gleichung stattfindet. Die Raster-Elektronenmikroskopie zeigt, daß die hergestellten kohlenstoffhaltigen Materialien andere Porenarten aufweisen als die kommerziellen Aktivkohlen. Die experimentellen Ergebnisse werden durch die molekularen Dimensionen der zur Adsorption verwendeten Substanzen und den Polarisationseffekt der Substituenten am Benzolring erklärt.
    Notes: Mixtures of phenol-formaldehyde-resin and pressed olive stones in a weight ratio of 20/80 were cured as small cylinders and then pyrolyzed. Some samples were also activated by steam. For these specimens and for two commercial activated carbons of laboratory or industrial uses the specific surface area, the structure, the adsorption properties, and the adsorption capacity were determined. The results indicate that the carbonaceous material produced by activation has greater values for the examined properties in comparison to the only pyrolyzed and the two commercial activated carbons, respectively. It was found that the Freundlich-equation is valid for the adsorption of 4-nitrophenol on all carbonaceous materials examined. The produced carbonaceous materials have different kinds of pores than the commercial activated carbons. The experimental results are explained with regard to the molecular dimensions of the adsorptive substances and the polarization effect of the substituents of the benzene ring.
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  • 67
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    Angewandte Makromolekulare Chemie 163 (1988), S. 101-114 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Anwendung der nichtlinearen Programmiermethode basierend auf der mittleren harmonischen Näherung wurden aus den Kontaktwinkeldaten die freie Dispersions- und polare, freie Oberflächenenergie, γSVd und γSVp, sowie die kritische, freie Oberflächenenergie, γc, von Polymeren bestimmt. Die Komponenten der freien Oberflächenergie der zu untersuchenden Flüssigkeiten, γLVd und γLVp, die die Bedingungen für den maximalen Wechselwirkungsparameter, Φ, wiedergeben, wurden ebenfalls mit Hilfe dieser Methode bestimmt.
    Notes: The dispersion and polar surface free energy components, γSVd and γSVp, and the critical surface free energy, γc, of polymers were determined from contact angle data by the application of a nonlinear programming method using harmonic mean approximation.The surface free energy components of the probe liquids, γLVd and γLVp, which reflect the conditions of the maximized interaction parameter, Φ, were also simultaneously determined by this method.
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  • 68
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    Angewandte Makromolekulare Chemie 153 (1987), S. 113-124 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Käufliche Weizenmehlstärke wurde unter Verwendung verschiedener Mengen Schwefelkohlenstoff und Acrylnitril xanthogeniert und cyanethyliert und dann zur Herstellung von modifizierten Stärke-Naturkautschuk-Masterbatches eingesetzt. Weiterhin wurden die Einflüsse untersucht, die die Gleichgewichte der Xanthogenierung und Cyanethylierung gegenseitig aufeinander ausüben. Die Ergebnisse werden auf der Basis definierter Wechselwirkungen zwischen der Xanthogenatgruppe und dem freien Acrylnitril erklärt. Hierbei führen sowohl sterische Faktoren als auch die höhere Elektrophilie des Acrylnitrils zum Zerfall der Xanthogenatgruppe. Daher kann die Cyanethylierung nur noch in einem geringeren Ausmaß erfolgen.
    Notes: Common wheat flour starch was subjected to xanthation followed by cyanoethylation at various levels of carbon disulfide and acrylonitrile to prepare modified starchnatural rubber masterbatches. Mutual influences of the extents of equilibrium xanthation and cyanoethylation on each other have been studied. The results have been explained on the basis of a definite interaction between xanthate group and free acrylonitrile in which both the steric factors and higher electrophilicity of acrylonitrile lead to the decomposition of xanthate groups and reduced the extent of cyanoethylation.
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  • 69
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Polychloropren und Polyvinylchlorid wurden Blends in verschiedenen Zusammensetzungen hergestellt und ihre Eigenschaften bestimmt. Die Eigenschaften der Blends zeigen, daß sie Polychloropren in vielen Anwendungen ersetzen können.
    Notes: Blends of polychloroprene rubber and plasticized polyvinylchloride have been prepared in various compositions and their properties evaluated. The properties of the blends show that they can be used to replace polychloroprene in many applications.
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  • 70
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The present paper describes a rheo-optical apparatus consisting of an elongational rheometer (with rotary clamps) and a device to measure birefringence. This equipment was designed to perform homogeneous deformations on polymer melts in the simple elongational mode. Elongational experiments were performed on polyisobutylene samples at room temperature using different strain rates (from \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} 0.01 s-1 to 1 s-1). In typical experiments homogeneous elongations up to λ ≈ 200 and stresses up to 2 · 106 Pa were achieved. The stress, the birefringence, and the deformation were obtained by measuring the force, the sample thickness, the optical retardation (the frequency of the sampling was 20 Hz) and the width of the sample (the frequency of the sampling was 3 Hz). It was found that the stress-optical coefficient was constant. The homogeneity of the deformations was carefully controlled because inhomogeneities cause serious errors in the measurements of elongational viscosity and birefringence.
    Notes: Es wird über eine rheo-optische Apparatur zur Verstreckung von Polymerschmelzen mit rotierenden Klemmen berichtet, die mit einer Doppelbrechungs-Meßeinrichtung ausgerüstet ist. Mit dieser Einrichtung können einfache Dehnungen an Polymerschmelzen bis zu hohen Verstreckgraden unter homogenen Bedingungen durchgeführt werden. Während des Deformationsvorganges können die Spannung, die Doppelbrechung und die Probendicke mit einer Meßrate von 20 Hz, sowie die Probenbreite mit ca. 3 Hz erfaßt werden.Wir haben Messungen an Polyisobutylen bei Raumtemperatur mit verschiedenen Dehngeschwindigkeiten (0,01 s-1 〈 \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} 〈 1 s-1) bis zu einem Verstreckgrad von λ ≈ 200 durchgeführt. Dabei wurden Spannungen bis zu 2 · 106 Pa erhalten. Das spannungsoptische Gesetz war bei homogener Versuchsführung stets erfüllt. Es wird gezeigt, daß ohne Kontrolle der Dehngeschwindigkeit und insbesondere bei inhomogener Dehung nicht nur Abweichungen vom spannungsoptischen Gesetz, sondern auch große Fehler bei der Spannungs- bzw. Viskositätsberechnung auftreten. Deshalb wurde großer Wert auf die Prüfung der Homogenität der Dehnung gelegt.
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  • 71
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    Angewandte Makromolekulare Chemie 153 (1987), S. 187-195 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The miscibility of various polymethylmethacrylate (PMMA)/polybutylmethacrylate (PBMA)/poly(methylmethacrylate-co-butylmethacrylate)systems has been studied. PMMA and PBMA are immiscible. Methacrylic homopolymers and copolymers are immiscible, too. A one-phase mixture from PMMA and PBMA is only accessible by copolymerization.
    Notes: Die Mischbarkeit von verschiedenen Systemen aus Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Poly(methylmethacrylat-co-butylmethacrylat) (P(MMA-co-BMA)) wurde untersucht. PMMA und PBMA sind miteinander nicht mischbar. Die untersuchten Homopolymeren und entsprechende Methacrylatcopolymere bilden ebenfalls heterogene Systeme. Einphasige Mischungen aus PMMA und PBMA sind nur über Copolymerisation erreichbar.
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  • 72
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    Angewandte Makromolekulare Chemie 163 (1988), S. 169-193 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The condensation reaction of bisphenol A, melamine, and formaldehyde was investigated by gel permeation chromatography, 13C-NMR-spectroscopy, IR-spectroscopy and elemental analysis. Because of the high reaction rates the condensation could be investigated only in the range of pH 6-10. At pH 6 and 7 the reaction of melamine with formaldehyde is dominating.With increasing pH-value the condensation of bisphenol A with formaldehyde is observed preferably. At pH 10 the condensation results in high molecular products. Cocondensation of melamine and bisphenol A through methylene bridges does not take place. But as a separation of the bisphenol A-formaldehyde condensates from the other condensation products was not possible, the three components may be connected through methylene-ether groups and/or intermolecular hydrogen bridges.
    Notes: Die gemeinsame Kondensation von Bisphenol A, Melamin und Formaldehyd wurde mit Hilfe der Gelpermeationschromatographie, der 13C-NMR-Spektroskopie, IR-Spektroskopie und Elementaranalyse untersucht. Wegen der hohen Kondensationsgeschwindigkeit verläuft die Reaktion in Gegenwart der drei Komponenten nur im Bereich von pH 6-10 kontrollierbar. Bei pH 6 und 7 überwigt die Kondensation zwischen Melamin und Formaldehyd. Mit steigendem pH-Wert tritt die Reaktion von Bisphenol A mit Formaldehyd in den Vordergrund und führt bei pH 10 zu hochmolekularen Kondensationsprodukten.Auf direkte Cokondensation hinweisende Methylenverknüpfungen zwischen der phenolischen Komponente und Melamin konnten nicht nachgewiesen werden. Die Kondensationsprodukte des Melamins bzw. des Bisphenol A mit Formaldehyd lassen sich aber nicht mehr vollständig aus den Reaktionsgemischen der Vorkondensation abtrennen, was dafür spricht, daß die Komponenten über Methylenetherbrücken und/oder intermolekularen Wasserstoffbrücken miteinander verknüpft sind.
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  • 73
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe der 13C-NMR-Spektroskopie wurde die Entwicklung der Oligomerenverteilung während der Polymerisation von 13C-angereichertem Ethylen mit dem löslichen Ziegler-Katalysatorsystem Cp2TiMeCl/AlMe2Cl verfolgt. Zuordnung und quantitative Auswertung aller Signale der verschiedenen wachsenden Ketten werden beschrieben. Die Geschwindigkeiten der Ethylen- und der Cp2 TiMeCl-Abnahme sowie die Bildungsgeschwindigkeit neuer Ketten konnten direkt aus den Spektren ermittelt werden. So läßt sich zum ersten Mal zeigen, daß die Konzentration der Ti-Propyl-und Ti-Pentylspezies in einen stationthen Zustand einlaufen. Dies ermbglicht, die Geschwindigkeitskonstanten der Ethyleninsertion in die Ti-Kohlenstoffbindung von Ti-Me, Ti-Pr und Ti-Pe zu ermitteln. Diese Ergebnisse fiihren zu einem detaillierten Ein-blick in den Ablauf der ersten Insertionsschritte und sind so eine Grundlage fur die mathematische Modellierung. Sie sind aufierdem ein weiterer unabhlngiger Beweis für die Giiltigkeit des dynamischen Modells des Mechanismus der Ethylenpolymerisation mit lbslichen Ziegler-Katalysatoren, nlmlich die Bildung der polymerisationsaktiven Spezies in zwei aufeinanderfolgenden sehr dynamischen Gleichgewichtsreaktionen.
    Notes: The development of the oligomer distribution during the polymerization of 13C-enriched ethylene by the soluble Ziegler catalyst system Cp2 TiMeCl/AlMe2Cl was followed by 13C-NMR spectroscopy. The assignment of the signals from the growing chains is described in full. It is shown that the rate of consumption of ethylene and Cp2 TiMeCl and the rate of formation of new chains can be monitored directly from the spectra. The concentrations of Ti-propyl and Ti-pentyl species during the polymerization were followed spectroscopically; both attain a steady state concentration. The relative rates were determined for the insertion of ethylene in the Ti-carbon bond of Ti-Me, Ti-Pr and Ti-Pe. These results give a detailed insight into the way that the oligomer distribution develops and provide a basis for its computer simulation. They also provide an independent proof that the dynamic model for the mechanism of ethylene polymerization with soluble Ziegler catalysts of the type Cp2 TiRCl/AlRnClm is correct.
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  • 74
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    Angewandte Makromolekulare Chemie 154 (1987), S. 99-110 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß verschiedener Reaktionsbedingungen auf die Bromierung von ataktischem Poly(propylen) (APP) in Tetrachlorkohlenstofflösung wurde untersucht. Mit zunehmender Reaktionszeit steigt der Bromierungsgrad. Auch mit steigender Verdünnung der APP-Lösung nimmt die Bromierungsgeschwindigkeit zu, welche bezüglich der APP-Konzentration die Ordnung 0,66 hat. Dies wird erklärt durch die anfängliche Substitution eines Wasserstoffs am tertiären Kohlenstoffatom. Die folgende H-Abstraktion an den benachbaren sekundären und primären Kohlenstoffatomen ist erleichtert. Die scheinbare Aktivierungsenergie wurde zu 11,9 kcal/mol bestimmt. Die Bromierungsgeschwindigkeit steigt bis zu einem APP : Br2-Molverhältnis von 1 : 1 an, darüber hinaus wird die Geschwindigkeit unabhängig vom Molverhältnis. Die Bromierung scheint folgendermaßen zu verlaufen: Nach anfänglicher Substitution eines tertiären H-Atoms durch freie Bromradikale werden nach und nach auchdie sekundäen und primären H-Atome durch weitergehende Substitution oder durch Addition nach einem Eliminierungsschritt ersetzt. Das IR-Spektrum bestätigt die Anwesenheit von Brom in den Proben.
    Notes: Effects of various reaction conditions on bromination of atactic poly(propylene) (APP) in carbon tetrachloride solution were studied. It was found that with the increase of the reaction time the extent of bromination increases. Also with an increased dilution of APP the rate of bromination increased following a bromination order of 0.66 with respect to APP concentration. This has been ascribed to initial replacement of the hydrogen at the tertiary carbon atoms followed by enhanced ease of abstraction from the neighbouring secondary and primary carbon atoms. The apparent activation energy was found to be 11.9 kcal/mol. The rate of bromination increases with an increase of the APP: Br2 molar ratio up to 1 : 1, beyond which the rate becomes independent of this ratio. Mechanism of bromination appears to be an initial substitution of tertiary H-atoms by bromine radicals followed subsequently by replacement of secondary and primary H-atoms via either progressive substitution or elimination-addition. IR spectra confirm the presence of bromine in the samples.
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  • 75
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    Angewandte Makromolekulare Chemie 163 (1988), S. 205-207 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cyclodextrin membrane-modified electrodes as sensor materials have been prepared by dipping platinum electrodes in the water suspensions of an oriented cyclodextrin polymer, followed by drying the polymer layers on the electrodes. The polymer is obtained by the solid-liquid reaction between the crystal of cyclodextrin inclusion complex and hexamethylene diisocyanate in anisole. The thickness (2 - 80 μm) of the cyclodextrin membrane is satisfactorily controlled by changing the concentration of the water suspension of the polymer. The cyclodextrin membranemodified electrodes show a significant response to p-nitrophenolate in water which is highly in contrast with no measurable response to o- and m-nitrophenolates.
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  • 76
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In this part properties and efficiency of the developed model1,2 are discussed. A variation of the parameters shows that vigorous effects are caused by the effective aggregation. All calculations show that at low conversion there are little temporal steps between the sequential aggregation steps. In the range of 5% to 20% conversion the velocity of aggregation decreases and the aggregative stability agrees with experiences given in the literature. It is shown that the calculated results are in agreement with the experimental results and therefore the presented model is a suitable possibility to describe the formation of some PVC-morphology properties.
    Notes: In der vorliegenden Arbeit werden die Eigenschaften des früher1,2 entwickelten Modells untersucht und diskutiert. Die Variation der Modellparameter zeigt einen großen Einfluß der Aggregationsprozesse auf die Subkornmorphologie. Bei niedrigen Monomerumsätzen ist das Zeitintervall zwischen zwei aufeinanderfolgenden Aggregationsschritten sehr klein, so daß für das Teilchenwachstum die Geschwindigkeit der Aggregation der Unterstrukturen entscheidend ist. Im Bereich zwischen 5% und 20% Monomerumsatz sinkt die Aggregationsgeschwindigkeit sehr stark, so daß für das Teilchenwachstum zunehmend die Polymerisationsreaktion an Bedeutung gewinnt. Aggregative Stabilität wird nach dem Modell für einen Teilchengrößenbereich erhalten, der sich in Übereinstimmung mit experimentellen Daten aus der Fachliteratur befindet. Die berechneten Teilchengrößen entsprechen ebenfalls den in der Literatur publizierten experimentellen Werten, so daß das Modell eine gute Grundlage für die Beschreibung einiger morphologisch bestimmter Polymereigenschaften bildet.
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  • 77
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    Angewandte Makromolekulare Chemie 165 (1989), S. 21-34 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden unidirektionale Verbundwerkstoffe aus Novolakharz mit Kohlenstoff-Fasern gemäß der Prepreg-Methode verarbeitet. Das Novolakharz wurde durch Polymerisation von Phenol mit Formaldehyd (Mol-Verhältnis 1 : 0,82) und Oxalsäure als Katalysator (1,5 Gew.-% von Phenol) hergestellt. Die Härtung des Novolakharzes wurde mit Hexamethylentetramin (Hexa) durchgeführt, während das geeignete Verhältnis durch die IR-Spektroskopie bestimmt wurde.Es wurden Proben aus Novolak/Hexa (Gew.-Verhältnis 14: 1), verstärkt mit kommerziellen Kohlenstoff-Fasern, unter verschiedenen Bedingungen (z. B. verschiedene thermische Programme und verschiedene Verhältnisse von Novolakharz : Kohlenstoff-Fasern) hergestellt. Die mechanischen Eigenschaften der hergestellten Proben (wie Biegefestigkeit, Zugfestigkeit, usw.) wurden bestimmt, und ihre Struktur wurde mit Hilfe der Elektronenmikroskopie untersucht.Mit zunehmendem Volumenverhältnis der Kohlenstoff-Fasern werden nicht nur alle mechanischen Eigenschaften des verstärkten Materials verbessert, sondern auch sein Nutzungsgrad nimmt zu, und die Herstellungsbedingungen üben einen größeren Einfluß aus. Die mit dem gleichen Verhältnis von Kohlenstoff-Fasern (z. B. 15 Vol.-%) hergestellten Proben weisen mit zunehmendem Härtungsgrad des Novolaks verbesserte mechanische Eigenschaften auf. Der Häirtungsgrad des Novolaks während der Anfangsphase (Gel-Zeit) als auch während der Endphase (Nachhärtung) kann mit Hilfe der IR-Spektren des härtenden Novolaks verfolgt werden, während der Härtungsgrad der Zwischenphase nur indirekt aus den Werten der mechanischen Eigenschaften der entsprechenden Proben bestimmt werden kann.Aus der Korrelation zwischen den Herstellungsparametern und den mechanischen Eigenschaften der Proben ergeben sich optimale Bedingungen für die Verarbeitung in der Wärmepresse zur Herstellung von mit Kohlenstoff-Fasern verstärkten Novolakharzen (1. Phase: T1 = 125-145°C, t1 = 20 min - 1 h, ohne Druck; 2. Phase: T2 = 180-195°C, t2 = 40 min, P2 ≃ 1,5 kN /cm2).
    Notes: Unidirectional composite materials of novolac resin with carbon fibers were fabricated according to the prepreg method. Novolac resin was prepared by polymerization of phenol with formaldehyde (mole ratio 1 : 0.82) in the presence of oxalic acid as catalyst (1.5 wt.-% to phenol). The curing of novolac resin was performed with hexamethylenetetramine (hexa), while the appropriate proportion was determined by using the IR-spectroscopy.Specimens of novolac/hexa (weight ratio 14:1) reinforced with carbon fibers commercially available were fabricated under different conditions (e.g. different thermal programs and different proportions of novolac/carbon fibers). The mechanical properties of the fabricated specimens (like flexural strength, tensile strength, etc.) were determined and their structure was examined by scanning electron microscopy.By increasing the volume proportion of carbon fibers, not only all mechanical properties of the composite material were increased, but also their degree of utilization was increased and also the production conditions had greater influence. Concerning the specimens produced by the same proportion of carbon fibers (e.g. 15 vol.-%) their mechanical properties were improved by increasing the curing of novolac. The degree of curing of novolac during the initial phase (gel time) and during the ultimate phase (post-curing) can be followed with the aid of IR-spectra of the cured resin, while the degree of curing for the intermediate phase can be obtained only indirectly from the values of the mechanical properties of the corresponding specimens.From the correlation between the production parameters and the mechanical properties of the samples the optimal conditions for processing of the thermopress for the manufacture of carbon fiber reinforced novolac were concluded (1. phase: T1 = 125-145°C, t1 = 20 min - 1 h, without pressure; 2. phase: T2 = 180-195°C, t2 = 40 min, P2 ≃ 1,5 kN/cm2).
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  • 78
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    Angewandte Makromolekulare Chemie 165 (1989), S. 69-78 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In dieser Arbeit interessieren wir uns für den Einfluß von Konzentration und Temperatur auf den elektrischen Widerstand eines Butyl-Kautschuks (IIR), der mit zwei Typen von Ruß (Hoch-Abrasion-Schmelzofen-Ruß (HAF) und Schnell-Extrusion-Hochofen-Ruß (FEF)) versetzt ist. Ergebnis war, daß die Leitfähigkeit bei niedrigem Rußgehalt hauptsächlich durch thermische Aktivierung der Ladungsträger erreicht wird. Bei mittleren Konzentrationen überwiegt der Tunnel-Mechanismus bei niedriger Temperatur, gefolgt von der thermischen Aktivierung bei relativ hoher Temperatur. Dies gilt für beide Rußarten. Das metallartige Verhalten bei Gemischen mit hoher Rußkonzentration kann sowohl der thermischen Ausdehnung der Tunnelwege zwischen Kohlenstoff-Agglomeraten als auch dem Zusammenbruch der Kohlenstoff-Agglomerate bei steigender Temperatur zugeschrieben werden.
    Notes: In this study we are interested in the effect of concentration and temperature on the electrical resistivity of butyl rubber (IIR) loaded with two types of carbon black, (namely, high abrasion furnace black (HAF), and fast extrusion furnace black (FEF)). It was found that the conductivity at low carbon black concentrations is mainly achieved by thermal activation of carriers. Tunneling mechanism at low termperature followed by thermal activation at relatively high temperature is found to be predominant for moderate concentrations for both carbon blacks. The metal-like behaviour which was observed in highly loaded compounds was attributed to both, the thermal expansion of the tunneling paths between carbon-carbon agglomerates and the breakdown of carbon agglomerates with temperature.
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  • 79
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    Angewandte Makromolekulare Chemie 165 (1989), S. 79-87 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Arbeit beschreibt die Synthese von Halogenderivaten des Phenylglycidylethers und die Möglichkeiten der Verwendung von diesen Komponenten als Flammverzögerer und reaktive Verdünnungsmittel für Epoxidharze.Mit Hilfe der Nelder-Mead-Simplexmethode wurden die besten Reaktionsbedingungen gefunden. Die so hergestellten Produkte zeichnen sich durch eine hohe Qualität aus und wurden mit einem niedermolekularen Epoxidharz gemischt und mit Diaminodiphenylmethan gehärtet.Die Viskosität von Harzgemischen und die Brennbarkeit der gehärteten Systeme wurden untersucht. Mit dem erhöhten Gehalt an Halogen (Chlor oder Brom) steigt die Viskosität, und die Brennbarkeit der Epoxide wird reduziert.
    Notes: This study deals with the synthesis of halogenated derivatives of phenyl glycidyl ether and with possibilities of their use as flame retardants and reactive diluents of epoxy resin.The best reaction conditions optimized by Nelder-Mead simplex method were found. The products of very high quality were prepared. They were mixed with a lowmolecular epoxy resin and cured by diamino diphenyl methane.The viscosity of the resin mixtures and limiting oxygen index of cured systems were determined. It was found that a higher content of halogen, both chlorine and bromine, causes increasing viscosity and reduced flammability of the epoxides.
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  • 80
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Messungen von Tg, Tm und Tc (Trübungspunkt) wurden Phasendiagramme der vier verträglichen Polymermischungen von chlorierten isotaktischen Polypropylenen (Chlorgehalt 39,2 (CPP-40) und 49,8 Gew.-% (CPP-50)) mit Poly(ethylen-co-vinylacetat)en (Vinylacetatgehalt 40 (EVA-40) und 45 Gew.-% (EVA-45)) untersucht. Von den vier Mischungspaaren war die Mischung von CPP-50 mit EVA-40 am besten verträglich.
    Notes: By measuring Tg, Tm and Tc (cloud point) phase diagrams for the four miscible blends of chlorinated isotactic polypropylenes (chlorine content 39.2 (CPP-40) and 49.8 wt.-% (CP-50)) with Poly(ethylene-co-vinyl acetate)s (vinyl acetate contents 40 (EVA-40) and 45 wt.-% (EVA-45)) were investigated. The blend of CPP-50 with EVA-40 was the most compatible of the four blend pairs.
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  • 81
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Synthese und Charakterisierung von Kationenaustauschmembranen aus PE-PS-DVB-Interpolymeren für die Elektrolyse von Borax-Lösung zur Erzeugung von Borsäure und Natronlauge wurden durchgeführt und mit den Eigenschaften von im Handel erhältlichen Membranen („Nafion 324“ und „Permaplex C-20“) verglichen.
    Notes: The synthesis and the characterization of the PE-PS-DVB interpolymer cationexchange membranes in the electrolysis of borax solutions to produce boric acid and sodium hydroxide simultaneously was carried out. The characterization of the teflon based “Nafion 324” and polystyrene-DVB based “Permaplex C-20” membranes was also performed in the same system for comparison.The DVB contents were varied between 3 - 12% (by wt. in total monomers) and the increase of the cross-links resulted in the decrease of the water contents and ionexchange capacities of the membranes. The PE present in the membrane acted as a barrier for electroosmotic water transport. The membranes with high DVB contents showed better electrolysis performance due to their low water contents and low electroosmotic water transport properties. The use of the interpolymer membrane containing 11.6% DVB resulted in high current efficiency and high sodium cation dynamic transport number and worked satisfactorily at the process conditions of borax electrolysis.
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  • 82
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    Angewandte Makromolekulare Chemie 165 (1989), S. 125-131 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Rizinusöl und difunktionellen Säuren, wie Oxal-, Malon-, Bernstein-, Glutar-, Adipin-, Suberin- und Sebacinsäure, wurden Prepolyester hergestellt. Diese Prepolyester (PPE) wurden anschließend mit Methylmethacrylat und 1% Ethylenglykoldimethacrylat als Vernetzer interpenetriert. Die Polymerisation wurde radikalisch mit Benzoylperoxid gestartet. Die neuen PPE/Polymethylmethacrylat (PMMA)-interpenetrierenden Netzwerke wurden als Pulver erhalten. Sie wurden durch ihr Löseverhalten, IR-Spektroskopie und ihr thermisches Verhalten charakterisiert.
    Notes: Prepolyesters were obtained from castor oil and dibasic acids, viz oxalic, malonic, succinic, glutaric, adipic, suberic and sebacic acid. These prepolyesters (PPE) were subsequently interpenetrated with methyl methacrylate containing 1% ethylene glycol dimethacrylate as crosslinker by radical polymerization initiated with benzoyl peroxide. The novel PPE poly(methyl methacrylate) PPE/PMMA interpenetrating polymer networks (IPNs) were obtained as powder. They were characterized by solubility behaviour, IR spectral study and thermal behaviour.
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  • 83
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2,4-Ionen, ein polymeres quartäres Ammoniumsalz, wurde auf einem makroporösen chlormethylierten Poly(Styrol-co-Divinylbenzol)-Harz (XAD-2) immobilisiert. Der Ionen-Gehalt des Harzes, der durch CHN-Elementaranalyse bestimmt wurde, betrug 50,2 g/kg Harz. Der wichtigste Nebeneffekt des modifizierten Harzes, das Ausbluten des Katalysators 2,4-Ionen, kann durch eine spektrophotometrische Methode, die extrem geringe Konzentraionen an freiem Ionen an der Oberfläche des Harzes messen kann, ermittelt werden.Die Aktivität der immobilisierten 2,4-Ionen/Kobalt(II)-phthalocyanin-tetranatriumsulfonat-Komplexe in bezug auf die oxidative Kupplung von Thiolen ist viel niedriger als im homogenen Fall, aber noch beträchtlich höher als im polymerfreien System. Die beobachtete Abnahme der Reaktionsgeschwindigkeit resultiert nicht aus Behinderungen des Massentransports, sondern vorzugsweise aus den Katalysatoreigenschaften wie z. B. einem sehr niedrigen N+/Co-VerhtUtnis. Die aktiven Zentren scheinen nur in der äußeren Hiille der Harzpartikel vorhanden zu sein.
    Notes: A poly(quaternary ammonium) salt, 2,4-ionene, has been immobilized on a macroporous chloromethylated poly(styrene-divinylbenzene) resin (XAD-2). The ionene content of the resin, determined by CHN elemental analysis, was 50.2 g/kg resin. The most important side effect of the modified resin, catalyst (2,4-ionene) bleeding, can be detected by a spectrophotometric method capable of determining extremely low concentrations of free ionene in the supernatant of the resin.The activity of these immobilized 2,4-ionene/cobalt(II)phthalocyanine-tetrasodiumsulfonate (CoTSPc) complexes towards the oxidative coupling of thiols is much lower than in the homogeneous case, but still considerably higher than for the polymer free system. The observed decrease in reaction rate does not originate from the considerable mass transfer resistances but predominantly from catalyst properties like a very low local N+/Co ratio. The active sites appear to be present in the outer shell of the resin particles only.
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  • 84
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Röntgendiffraktometrische Untersuchungen und DSC-Messungen an Blend-Filmen, die aus Lösungen von PEEK und PES hergestellt wurden, zeigen eine Phasenseparation bei den Filmen, die bei 340°C hergestellt wurden. Das Kristallisationsverhalten von Filmen, die bei 340°C hergestellt, anschließend abgeschreckt und bei 180°C getempert wurden, ist identisch mit dem von PEEK. Filme, die bei 300°C hergestellt wurden, kristallisierten erst durch Tempern bei 250°C. Blockcopolymere, die aus Oligomeren von PEEK und PES erhalten wurden, unterscheiden sich in dieser Hinsicht von Blends der gleichen Zusammensetzung. Die Glastemperatur von Copolymeren mit einem PEEK-Gehalt von mehr als 50% liegt höher als die von PEEK selbst, während der Schmelzpunkt dieser Copolymeren niedriger als der von PEEK ist.
    Notes: Polymer blends of PEEK with PES were prepared by the solution blending method. Copolymers composed of PEEK and PES components were synthesized from these oligomers. The formation conditions exerted an influence over the molecular aggregation and the crystallization behaviors of the blend films and block copolymers which were examined by X-ray diffractometry and DSC analysis. As a result, phase-separation in the blend films was found when the formation temperature was high. The blend films formed at 340°C, quenched and annealed at 180°C, exhibited the same crystallization behavior as those of PEEK. In the case of the blend films formed at 300°C, the annealing of the films at 250°C was required to crystallize the blend films. The Tg of a copolymer with a PEEK component content of more than 50% tends to shift toward a higher temperature than the Tg of PEEK itself, and the Tm of the copolymer toward a lower temperature than that of PEEK ist.
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  • 85
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Im Zusammenhang mit dem Studium des Wirkungsmechanismus von industriell hergestellten Antidegradantien vom Typus der N-Phenyl-N′-sek-alkyl-1,Cphenylendiamine wurde die Reaktion von N-Phenyl-1,4-benzochinonimin (I) und 4-Hydroxydiphenylamin (II) mit dem Kohlenstoff-Radikal 1-Cyano-l-methylethyl (R·) studiert. Das Gemisch von I und II reagiert mit R· sehr leicht unter Bildung der Verbindungen III, VI und VIII. I allein reagiert wesentlich langsamer, und das Reaktionsgemisch enthält mehrere Produkte. Neben der Verbindung III wurden auch die Verbindungen IV und VII identifiziert. II allein reagiert bei denselben Bedingungen nicht. Die Verbindung IV bildet die zwei isomeren Strukturen syn und anti. Die Verbindung VIII ist ziemlich unbeständig; aus ihren Umwandlungsprodukten wurde XI isoliert. Bei der Reduktion von IV entsteht die Verbindung V, die ähnlich wie VIII unbeständig ist.
    Notes: The reaction of N-phenyl-1,4-benzoquinoneimine (I)Decoding of abbreviations see p. 103/104. and 4-hydroxydiphenylamine (II) with the carbon centred 1-cyano-1-methylethyl radical (R·) was studied in connection with an investigation of the action mechanism of industrial antidegradants, such as N-phenyl-N′-sec-alkyl-1,4-phenylenediamines. The mixture of I and II reacts very readily with R·, giving rise to III, VI, and VIII. I alone reacts much slowlier, and the reaction mixture contains more products. IV and VII were identified along with III. Under the conditions used, II alone does not react at all. IV exists in two isomeric forms, syn and anti. VIII is very labile; XI was isolated from its transformation products. Reduction of IV gives V, which is labile, similarly to VIII.
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  • 86
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    Angewandte Makromolekulare Chemie 156 (1988), S. 123-137 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Samples of polyoxymethylene (unstabilized and stabilized with the antiozonants N-isopropyl-N′-phenyl-p-phenylenediamin (IPPD) and bis-(1,2,3,6-tetrahydrobenzaldehyd)pentaerithritylacetal (Vulkazon AFS)) were ozonized under mechanical load in a special climate chamber. Surface damages were determined by IR-spectroscopy and scanning electron microscopy. During the ozonolysis a damaged layer is formed, the thickness of which increases with increasing time of ozonization. During this damaging reaction acetal groups are attacked and oligomers are formed.
    Notes: Proben von unstabilisiertem und mit den Antiozonantien N-Isopropyl-N′-phenyl-p-phenylendiamin (IPPD) und Bis-(1,2,3,6-tetrahydrobenzaldehyd)-pentaerithrityl-acetal (Vulkazon AFS) stabilisiertem Polyoxymethylen wurden unter mechanischer Belastung in einer Klimakammer ozonisiert. Die Schädigungen auf der Oberfläche wurden IR-spektroskopisch und rasterelektronenmikroskopisch untersucht. Während der Ozonisierung von POM bildet sich eine geschädigte Schicht, deren Dicke mit zunehmender Ozonisierungszeit wächst. Hierbei wird das Polymere an den Acetalbindungen angegriffen, wodurch Ketten gespalten werden und Oligomere entstehen.
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  • 87
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    Angewandte Makromolekulare Chemie 156 (1988), S. 105-121 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe verschiedener Methoden wurde der Einfluß der Entfernung unterschiedlicher porenbildender Verdünner aus porösen Styrol-Ethylstyrol-Acrylnitril-Divinylbenzol-Copolymeren auf die Netzwerkstruktur untersucht. Der günstigste Weg, den ursprünglichen strukturellen Bau des porösen Netzwerkes zu bewahren, welches in Gegenwart von solvatisierenden Verdünnern erhalten wurde, ist das Entfernen des inerten Mediums mit Methanol. Wenn die Wasserdampfmethode angewendet wird, fin det der sog. Kollapseffekt statt, und die aus solchen Harzen hergestellten Anionenaustauscher adsorbieren weniger Farbstoff im Vergleich zu jenen, die aus Perlen hergestellt worden sind, die mit Methanol behandelt wurden; Grund hierfür ist die durch den Kollaps veränderte Porengröße. Es wurde ebenfalls festgestellt, daß die in Anwesenheit von solvatisierenden Verdünnern (Mischungen aus Quellungs- und Fällmitteln) hergestellten Copolymeren in Methanol sehr gut quellen, obwohl dieses ein Fällungsmittel für Polystyrol ist.
    Notes: The influence of the removal of various diluents, pore forming agents from the porous styrene-ethylstyrene-acrylonitrile-divinylbenzene copolymers on the structure of the matrix was investigated by several methods. The most advantageous pathway to preserve the initial structural edifice of the porous networks performed in the presence of solvating diluents consisted in the removal of the inert media with methanol as it was noticed from the experimental data. If the steam treatment is applied, the collapse effect takes place and the anion exchangers prepared from such matrices exchange/adsorb less dye stuff by comparison with ones formed from beads treated with methanol, because the pore size was changed. It was also noticed that the porous copolymers performed in the presence of the solvating diluents (mixtures of solvatings and precipitants) swell very well in methanol though it is a precipitating medium for the polystyrenic macromolecular chains.
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  • 88
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    Angewandte Makromolekulare Chemie 156 (1988), S. 139-149 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: An Styrol-Zinkacrylat-Copolymeren wurde die Abhängigkeit der Glasübergangstemperatur von der Aufheizgeschwindigkeit und der Zusammensetzung mit Hilfe der Differential-Scanning-Calorimetrie untersucht. Die Thermogravimetrie wurde benutzt, um die Pyrolyse dieser Copolymeren an Luft bei drei verschiedenen Aufheizge-schwindigkeiten zu untersuchen. Die thermische Zersetzung von Ionomeren ist ein 3-Stufen-Prozeß. Die Reaktionsordnung und Aktivierungsenergie wurde für jede Stufe der Zersetzung bestimmt unter Verwendung eines Computerprogramms, das auf den Methoden von Kissinger, Freeman-Carrol und Ozawa basiert. Es zeigte sich, daß die thermische Stabilität durch die ionischen Gruppen abnimmt.
    Notes: The dependence of glass temperature on the heating rate and the composition for styrene-zinc acrylate copolymers has been investigated by differential scanning calorimetry. Thermogravimetry was used in order to examine these copolymers undergoing pyrolysis in an atmosphere of air at three different heating rates. Thermal decomposition of ionomers is a three-stage process. The orders and activation energies have been determined for each stage of decomposition using the computer programs based on the methods of Kissinger, Freeman-Carrol, and Ozawa. It was found that the heat stability is lowered by the ionic groups.
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  • 89
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    Angewandte Makromolekulare Chemie 156 (1988), S. 151-162 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Pfropfung der hydrophilen Monomeren N-Vinylpyrrolidon, 2-Hydroxyethyl-methacrylat und Acrylamid auf ungesättigte segmentierte Polyurethane in N,N-Dimethylformamid mit 2,2′-Azobisisobutyronitril als Initiator wurde untersucht. Die Pfropfcopolymeren wurden von den Homopolymeren durch selektive Extraktion in Soxhlet-Apparaturen abgetrennt. Die kinetische Untersuchung der Pfropfcopolymerisation zeigte, daß die Reaktionen dem gewöhnlichen kinetischen Verhalten radikalischer Polymerisationen folgen. Die Abhängigkeiten der Pfropfungsgeschwindigkeit von der Initiator- und N-Vinylpyrrolidonkonzentration waren von 0,5 bzw. 1,0 Ordnung. Für 2-Hydroxyethylmethacrylat wurden sie zu jeweils 0,5 und 2,0 gefunden. Die Gesamtaktivierungsenergie der Pfropfcopolymerisation des 2-Hydroxyethylmethacrylats und des N-Vinylpyrrolidons betragen jeweilig 21,81 und 16,28 kJ/mol.
    Notes: Grafting of unsaturated segmented polyurethanes with some hydrophilic monomers such as N-vinyl pyrrolidone, 2-hydroxyethylmethacrylate and acrylamide in N,N-dimethylformamide have been studied using 2,2′-azobisisobutyronitrile (AIBN) as initiator. Graft copolymers were isolated from homopolymers by selected solvent extraction using a Soxhlet apparatus. A kinetic study of graft copolymerization reactions showed that the reactions follow the conventional kinetic behaviour of free radical polymerization. The dependencies of the grafting rate on initiator and N-vinyl pyrrolidone concentrations were of 0.5 and 1.00 order, respectively. However, for the 2-hydroxyethylmethacrylate, the dependencies of the grafting rate on initiator and monomer concentrations were found to be of 0.5 and 2.00 order, respectively. The overall activation energy for the graft copolymerization of the 2-hydroxyethylmethacrylate and N-vinyl pyrrolidone were 21.81 kJ/mol and 16.28 kJ/mol, respectively.
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  • 90
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    Angewandte Makromolekulare Chemie 156 (1988), S. 179-185 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultra fine particles were impregnated by using a finely porous cellulose gel membrane. The impregnated gel membrane is a green transparent one and looks like a solid solution. Highly dispersed Ni catalysts on carbon were obtained from thermal decomposition of these gel membranes. The particle size is in the range of several nm to a few ten nm. They show interesting catalytic properties for hydrogenation of olefins such as cyclooctadiene.
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  • 91
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermo-oxidation resistance and weatherability of LDPE and HDPE compositions, containing up to 45 wt.% calcium carbonate, are investigated. The thermo-oxidation resistance is investigated by dynamic DTA and natural ageing is carried out in an exposure station in a seaside climate. The change in strength and colour after ageing is determined. The behaviours of filled and unfilled polymers are compared. Empirical equations are given, describing the change in the investigated parameters during natural ageing.
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  • 92
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: An Proben aus Polypropylen, die bei sehr unterschiedlichen Einstellungen von Spritzgußmaschinen und Extrudern hergestellt wurden, stellten sich deutliche Abhängigkeiten des Alterungsverhaltens von den thermischen und mechanischen Produktionsparametern ein, die nicht durch unterschiedliche Schmelzetemperaturen bedingt sind. Insbesondere kann ausgesagt werden, daß bei Spritzguß eine hähere Scherbelastung und damit stärkere Orientierungen -eine stärkere Veränderung der Eigenspannungen hervorrufen-einen früheren Glanzabfall und-eine geringere Initialzeit bis zur Rißbildung bewirken.Bei Extrusion fiihrt eine geringere Abkühlgeschwindigkeit und damit ein gröberes Gefüge zu -einer stärkeren Veränderung der Eigenspannungen-einem friiheren und ausgeprägteren Glanzverlust-sowie zu einem früheren Abfall der Reißdehnungen.Unbekannt ist, -ob diese Wirkungen auch bei anderen Thermoplasten als PP auftreten-ob sie auch bei stabilisierten Systemen in relativ gleichem Umfange auftreten-und ob es sich lohnt, die beobachteten Effekte ggf. durch ge zielte Maschineneinstellungen auszunutzen.Auf jeden Fall sollten auf diesem Gebiet weitere Arbeiten durchge-führt werden.
    Notes: Specimens of unmodified polypropylene have been manufactured using extreme adjustings of injection moulding machines and extruders. After artificial weathering, distinct relations of ageing processes to thermal and mechanical production parameters were found, which are not influenced by different melting temperatures. It can be started in particular, that during injection moulding a larger shear stress (resulting in more distinct orientation) results in -a greater change in residual stresses-an earlier gloss reduction-a shorter initial period before cracking.During extrusion a lower cooling rate (resulting in a coarser structure) leads to -a greater change in residual stresses-an earlier and more distinct gloss reduction-an earlier loss of ultimate strain.It remains unknown, whether -these relationships will be similar with other thermoplastic materials than PP-these relationships appear to the same relative extend with stabilized systems-it may be advantageous, to use the observed effects by adjusting the injection moulding and extrusion machines in a special way.It seems to be significant to do more research work in this field.
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  • 93
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    Angewandte Makromolekulare Chemie 160 (1988), S. 1-15 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(tetramethylenadipat)diol mit einer Molmasse von 2000 wurde bei Temperaturen von 60 und 80°C in Gegenwart von Wasser bzw. 1,4-Butandiol sowie den gebräuchlichsten PUR-Katalysatoren (Dabco und Dibutylzinndilaurat) gelagert und die Solvolyse untersucht. Die Geschwindigkeit der Solvolyse nimmt mit steigender Temperatur deutlich zu. Die Alkoholyse wird durch Dibutylzinndilaurat weitaus stärker katalysiert als durch 1,4-Diazabicyclo[2.2.2]oktan. Die Hydrolyse verläuft langsamer, da vermutlich die Katalysatoren bei diesem Prozeß desaktiviert werden. Die mechanischen Eigenschaften von Polyurethanen, die mit den partiell abgebauten Diolen hergestellt wurden, korrelieren gut mit der Abnahme der Molmasse.
    Notes: Poly(tetramethylene adipate)diol having a molar mass of 2000 was stored at temperatures of 60 and 80°C in the presence of water or 1,4-butanediol and a common PUR-catalyst like 1,4-diazabicyclo [2.2.2]octane (DABCO) or dibutyltindilaurate (DBTL) and the solvolysis was investigated. The rate of solvolysis is low at 60°C except for DBTL and shows a drastic increase at 80°C. In the alcoholysis reaction DBTL is a much more active catalyst than DABCO. The rate of hydrolysis is slower probably because the catalysts are deactivated by the acidic products formed in this process. The mechanical properties of polyurethanes made from the degraded polyols are in good correlation with the decrease in molar mass.
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  • 94
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    Angewandte Makromolekulare Chemie 160 (1988), S. 17-28 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Zugabe von Bis(allylphenyl) Typ (TM 120)-Monomeren auf die Eigenschaften von unidirektional mit Carbonfasern verstärkten 4,4′-Bismaleimidodiphenylmethan (BM) - 2,4-Tolylendiamin (A) (1:0,3 Molverhältnis) (BM-A)-Verbundkörpern wird vorgestellt. Das Aushärteverhalten sowie das thermische Verhalten in Luft wurde mit Hilfe der Differentialkalorimetrie (DSC) und der Thermogravimetrie (TGA) untersucht. Die thermische Stabilität nimmt mit ansteigenden Konzentrationen von TM 120 deutlich zu. Demgegenüber steht ein Anstieg der Biegefesigkeit, der interlaminaren Scherfestigkeit sowie der Schlagzähigkeit mit zunehmender Monomerkonzentration. Optimale mechanische Eigenschaften wurden bei etwa 20 Tle./100 Tle. TM 120 erreicht.
    Notes: The paper deals with the effect of addition of bis(allylphenyl) type (TM 120) monomer on the properties of unidirectionally carbon fibre reinforced 4,4′ bismaleimidodi-phenyl methane (BM) - 2,4-tolylene diamine (A) (1:0.3 molar ratio) (BM-A) composites. The curing and thermal behaviour of the blends was investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in air atmosphere. A marginal decrease in thermal stability was observed with increasing concentration of TM 120. Flexural, interlaminar, and impact strength of the laminates increased in the presence of this monomer. Optimum mechanical properties were observed at ∼ 20 phr of TM 120.
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  • 95
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In dieser Arbeit wurden Veränderungen des verschweisßten Rohr- und Fittingmaterials (isotaktisches Polypropylen Homo- bzw. Copolymer PP-R grau pigmentiert) wührend der für die Praxis relevanten Innendruckversuche untersucht.Bei der technischen Verschweißung von Polyolefinen entstehen charakteristische Gefüigezonen im Schweißnahtbereich, welche vom Fßgematerial und den Fngebedingungen beeinflußt werden. In der vorliegenden Untersuchung wurden sowohl die Materialcbergange im Fiigebereich (mit den Methoden - schichtenweise Differentialkalorimetrie, Polarisations- bzw. Elektronenmikroskopie sowie Fluoreszenzspektroskopie mit extrem hoher Ortsauflösung) als auch die Eigenspannungen hinsichtlich ihrer Verlnderung bei Langzeitpriifung im Innendruckzeitstandversuch bei 95°C bis zu einer Prüfzeit von 18.100h untersucht.Die Abbauvorgänge der Makromoleküle bei der Langzeitprüfung der 364 untersuchten Schweißmuster werden in einer gesonderten Arbeit behandelt (1).Durch die Innendruckversuche bei 950 C findet eine Nachkristallisation und eine Gefügevergrijberung sowohl in der Schweißnaht als auch im Gefüge der Schweißpartner statt. Dabei werden die beim Schweißvorgang eingebrachten Orientierungen und Eigenspannungen unter dem Einfluß von Wärme beim Innendruckversuch weitgehend abgebaut. Durch die unter Druckeinwirkung einsetzenden Flieävorgange jedoch werden neue Eigenspannungen eingebracht.Es konnte gezeigt werden, daß bei guter Verschweißung von PP mit PPCO ein kontinuierlicher Übergang (Mischungsbereich) vom Homopolymeren zum Copolymeren auftritt, der auch beim Langzeiteinsatz im Innendruckversuch erhalten bleibt.
    Notes: The present study deals with changes of welded material of pipes and fittings (isotactic polypropylene homo and copolymer PP-R grey pigmented) during the standardized internal pressure tests, which are commonly used for these products.Technical welding of polyolefines causes characteristic structures, which depend on the natural of the welded material and the welding conditions.In this investigation both the transition of material in the welding seam and the changes of internal stresses during internal pressure tests at 95°C until 18.100h test time were examined. The methods we used were Differential calorimetry of think layers, Polarization- and Electron microscopy, Fluorescence spectroscopy with extreme high local resolution.The effects of decomposition of the macromolecules in the welded samples during the internal pressure tests will be described in a separate paper (1).The internal pressure tests at 95O C cause a recrystallization and an increase of the particle size in the structure of the welding seam and in the structure of the welded parts themselves. Under the above described testing conditions the orientations and internal stresses initiated by the welding procedure will relaxe influenced by heat. However the creep effects that occur in the material when exposed to pressure introduce new internal stresses. It could be shown that in perfectly welded parts a continuous transition from PP to PPCO occurs, which did not change after long time application of internal pressure tests.
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  • 96
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    Angewandte Makromolekulare Chemie 168 (1989), S. 129-134 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Reaktionsprodukt eines Cyclohexanon-Formaldehyd-Harzes mit dem Säurechlorid des Radikalinitiators 4,4′-Azo-bis(4-cyanopentansäure) wurde als Initiator für die Styrolpolymerisation eingesetzt, um ein Cyclohexanon-Formaldehyd-Harz/Polystyrol-Copolymeres zu bilden. Das Copolymere zeigte ähnliche Löslichkeit wie Polystyrol.
    Notes: The reaction product of cyclohexanone-formaldehyde resin with an acid chloride of a radical initiator, 4,4′-azo-bis(4-cyano pentanoic acid) was used as initiator for styrene polymerization to form a cyclohexanone-formaldehyde resin/polystyrene copolymer. The copolymer showed similar solubility as polystyrene.
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  • 97
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    Angewandte Makromolekulare Chemie 168 (1989), S. 145-155 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Entgegengesetzte Ladungen wurden durch tertiäre Amin- und Carboxylgruppen in Polyurethan (PU) und Polystyrol (PS) eingeführt, um durch gemeinsame Massepolymerisation ein interpenetrierendes PU/PS Polymernetzwerk (IPN) zu erhalten. Vier IPNs wurden hergestellt: ein Voll-IPN, zwei Semi-IPNs und ein lineares Blend. Die Wirkung der geladenen Gruppen auf die mechanischen Eigenschaften und die Morphologie der vier Polymermischungen wurde untersucht.Es wurde gefunden, daß PU/PS IPNs mit geladenen Gruppen keine Phasenseparation und somit homogene Verteilung aufweisen, was durch elektronenmikroskopische (SEM) Aufnahmen nachgewiesen wurde. Dynamisch-mechanische Messungen zeigen, daß die Übergangspeaks des Verlust-Moduls E″ in die Mitte zwischen den beiden Übergangspeaks der beiden Komponenten ohne geladene Gruppen liegen. Dies ist von der Zunahme des Gehaltes an geladenen Gruppen abhängig. Gleichzeitig nimmt der Speichermodul E′ in einer Stufe ab, was im Gegensatz zu der zweistufigen Abnahme bei Proben ohne Ladungsträger steht.Die Zugfestigkeit nimmt in allen vier Polymermischungen mit der Zunahme an Acrylsäure (AA) in Poly(Styrol-Acrylsäue) PSAA zu, was in dem PU/PSAA Voll-IPN besonders deutlich wird.
    Notes: Opposite charges, namely tertiary amine and carboxyl groups, were introduced into polyurethane (PU) and polystyrene (PS), respectively, to prepare PU/PS interpenetrating polymer networks (IPNs) by means of simultaneous bulk polymerization. Four IPNs were synthesized: a full-IPN, two semi-IPNs and a linear blend. The effect of charge groups on the mechanical properties and morphology of the four polymer alloys was investigated.It is found that the PU/PS IPN which was incorporated with charge groups is free of any phase-separation, and sufficiently uniformly distributed, as can be seen from the corresponding scanning electron microscopy (SEM) photographs. Dynamic mechanical analysis indicates that the transition peak of the loss modulus E″ will move towards the centre between the two transition peaks of both components in the absence of charge groups, as a function of an increase in the contents of the opposite charge groups. Meanwhile the storage modulus E′ will decrease in a single-stage way from the previous two-stage mode.The tensile strength in all the four polymer alloys increased markedly along with an increase in the contents of acrylic acid (AA) in the poly(styrene-acrylic acid) (PSAA), which clearly can be seen for the PU/PSAA full-IPN.
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  • 98
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    Angewandte Makromolekulare Chemie 168 (1989), S. 157-168 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Pyrolysis behaviour and coke characteristics of different precursors for carbon processing: thermosetting resins (resol, novolak), hydrolytic lignin, pitch, tar as well as their blends were studied using differential thermal analysis (DTA) and X-ray diffraction techniques. The blends novolak-pitch, resol-tar and resol-hydrolytic lignin show a higher coke yield after carbonisation up to 1000°C compared to the corresponding individual substances. A good correlation between the integral procedural decomposition temperature T*A of the investigated precursors and their coke yield is found.
    Notes: Mittels Thermo- und Röntgenstrukturanalyse wird eine vergleichende Untersuchung des Pyrolysevorganges und der Mikrostruktur des aus zwei Gruppen organischer Bindemittel und deren Mischungen gewonnenen Koksrückstandes durchgeführt. Gruppe I umfaßt reine und mit Hydrolyselignin gefüllte Resol- und Novolak-Phenol-Formaldehydharze und Gruppe II Steinkohlenpech und -teer. Es wird festgestellt, daß sich die Mischungen Novolakharz-Pech, Resolharz-Teer und Resolharz-Hydrolyselignin beim Erhitzen nicht wie mechanische Gemische verhalten und eine erhöhte Ausbeute an Koksrückstand liefern. Weiterhin wird gefunden, daß die integrale Endtemperatur der Pyrolyse (T*A) dieser Substanzen als quantitatives Maß für die Ausbeute an Koksrückstand im Anschluß an die Carbonisierung der Proben dienen kann.
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  • 99
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    Angewandte Makromolekulare Chemie 168 (1989), S. 217-223 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The paper describes the successful synthesis of silicon containing bismaleimide resin 4,4′-carbo(4,4′-bismaleimido phenoxy)diphenyl silane. The char yield of the bismaleimide resin in N2 atmosphere was found to be 55% at 800°C. Chain extension of bismaleimide with 4,4′-diamino diphenyl sulfone reduced the char yield and thermal stability.
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  • 100
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    Angewandte Makromolekulare Chemie 160 (1988), S. 67-81 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden neue Coordinationspolymere mit Schiffschen Basen aus Terephthalal dehyd und S-Benzyldithiocarbazol als Liganden in DMF-Lösung hergestellt. Die erhaltenen Coordinationspolymeren wurden durch Elementaranalyse, magnetische Suszeptibilität, elektronische und IR-Spektroskopie charakterisiert. Die durch Thermogravimetrie bestimmte thermische Stabilität der Coordinationspolymeren nahm in der folgenden Reihenfolge ab: \documentclass{article}\pagestyle{empty}\begin{document}${\rm Zn} \simeq {\rm Fe} 〉 {\rm Co} 〉 {\rm Ni} 〉 {\rm Min} \simeq {\rm Cu}$\end{document} Mn(II)-, Fe(II)-, Co(II)- und Ni(II)-Coordinationspolymere haben eine Oktaederstruktur mit der Koordinationszahl6, während bei den Cu(II)- und Zn(II)-Coordinationspolymeren eine 4-fach koordinierte quadratisch-planare bzw. eine tetraedrische Struktur gefunden wurde. Ligandenfeld- und nephelawetische Parameter wurden aus den Spektren errechnet. Dam wurde die Ligandenfeldtheorie spin-erlaubter Übergänge angewandt, die sich als konsistent mit einer 6-fach koordinierten Struktur für Mn(II)-, Fe(II)-, Co(II)- und Ni(II)-Coordinationspolymere erwies. Die Elementaranalysen ergaben bei allen Coordinationspolymeren ein Ligand: Metall-Verhältnis von 1 : 1 und deuteten bei den Mn(II)-, Fe(II)-, Co(II)- und Ni(II)-Coordinationspolymeren auf am Zentralatom assoziierte Wassermoleküle hin.
    Notes: New Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) coordination polymers of Schiff base ligand derived from terephthalaldehyde and S-benzyldithiocarbazate have been synthesized in DMF media. The coordination polymers have been characterized by their elemental analysis, magnetic susceptibility, and by electronic and infrared spectral measurements.The thermal stability of each polymer was found out by thermogravimetric analysis. The thermal stability of coordination polymers obtained from thermograms has the following order: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Zn} \simeq {\rm Fe} 〉 {\rm Co} 〉 {\rm Ni} 〉 {\rm Min} \simeq {\rm Cu}$\end{document} Mn(II), Fe(II), Co(II), and Ni(II) coordination polymers are of a six-coordinated octahedral structure while Cu(II) and Zn(II) coordination polymers are found to be four-coordinated square planar and tetrahedral structure, respectively. The ligand-field and nephelauxetic parameters have been determined from the spectra, using ligand-field theory of spin-allowed transitions which are found consistent with six-coordinate structure for Mn(II), Fe(II), Co(II), and Ni(II) coordination polymers. Elemental analyses indicates a ligand: metal ratio of 1 : 1 in all the coordination polymers and the association of water molecules with central metal atom in case of Mn(II), Fe(II), Co(II), and Ni(II) coordination polymers.
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