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  • Polymer and Materials Science  (11)
  • General Chemistry  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 129-141 
    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 Wirkung von aliphatischem Korrosionsschutzöl auf das Aushärte- und Abbauverhalten eines ölkompatiblen Epoxidharzklebers wurde mittels Differentialkalorimetrie (DSC), Fourier-Transformations-Infrarot-Spektroskopie (FTIR) und Thermogravimetrie (TGA) untersucht. Die Ergebnisse der DSC- und FTIR-Messungen deuten darauf hin, daß die Härtungsgeschwindigkeit des untersuchten Epoxid-Systems durch das Vorhandensein des Öls nur wenig beeinflußt wird. Dennoch bestätigt das Absinken der exothermen Härtungskurve, begleitet von einer Verbreiterung des Glasübergangstemperaturbereichs, daß das Öl den Aushärtemechanismus beeinflussen kann und in der Lage ist, die Struktur des gehärteten Harzes zu verändern. Außerdem geht aus den TGA-Messungen hervor, daß die Temperaturbeständigkeit des Harzes sich in Gegenwart des Öls verschlechtert; dies wird auf Veränderungen in der Struktur und im Abbaumechanismus des Epoxid-Systems zurückgeführt.
    Notes: The effect of aliphatic slushing oil on the curing and degradation behavior of an oil-accommodating epoxy adhesive is studied by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results of FTIR and DSC indicate that the curing rate of the tested epoxy system is little affected in the presence of the oil. However, the decrease of the curing exotherm accompanied with a broadening of the glass transition confirms that the oil can affect the curing mechanisms and may change the structure of the cured resin. Additionally, it is evident from the TGA results that the thermal resistance of the resin deteriorates in the presence of the oil, which is attributed to the changes in the structure and the degradation mechanism of the epoxy system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 3121-3131 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transport behavior of He, O2, N2, and CO2 in membranes of poly(vinyl chloride) (PVC)/acrylonitrile-butadiene-styrene (ABS) blends has been studied at 25°C. The blends were further characterized by dynamic mechanical measurements, differential thermal analysis (DTA), density measurements, and x-ray diffraction. The equilibrium sorption of CO2 and N2 was measured directly at atmospheric pressure using an electromicrobalance and compared with sorption values obtained as P/D ratios from permeation measurements. The rates of permeation (P) and diffusion (D) increase with increasing ABS content in the blends. The P and D values are not additive, and only slight indications of phase inversion in the blends are observed at 5-10 wt-% ABS in the blends. Experimental densities of the blends are higher than calculated densities assuming volume additivity. The data are interpreted to mean that the PVC/ABS blends form a two-phase system composed of a soft polybutadiene (rubber) phase and a rigid PVC/styrene-acrylonitrile copolymer (SAN) phase of mutually compatible components. DTA and dynamic mechanical measurements also show a two-phase system. Sorption values of CO2 and N2 by equilibrium sorption measurements increase with increasing ABS content in the blends without the large fluctuations which have been observed for the sorption values obtained from the time lag method. Comparison of the two types of sorption values (from direct measurements and from P/D ratios) show larger deviations for CO2 than for N2. This suggests that the time lag method is not valid for permeants with polar character in heterogeneous two-phase systems where chemical immobilizing effect on the permeant molecules occurs.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1255-1265 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements of mechanical damping (tan δ) in the temperature range of -120° to +120°C at 110 Hz, of uniaxial tensile creep at 25.0° ± 0.5°C covering creep times from 10 to 1000 sec, and of impact strength at 21°C have been carried out for a series of physical PVC/PCL blends in the composition range of 0%-12% by weight of PCL in the blend. With increasing PCL content in the blend, the α-peak of PVC was shifted to lower temperatures and became broadened. The β-peak of PVC was also shifted to lower temperatures and was markedly suppressed. The tensile creep compliance of approximately linear viscoelasticity showed a maximum decrease of 10%, and the impact resistance was reduced 3.5 times when 5% and 12% by weight of PCL, respectively, was blended with PVC. There was also a considerable increase (25%) in stress level at which the transition from approximately linear to markedly nonlinear viscoelasticity occurred when up to 5% by weight of PCL was added to the PVC. These results are attributed to the antiplasticizing effect of PCL on PVC. They support the importance of β-mechanism in the stress-activated processes proposed to be responsible for the appearance of nonlinear viscoelasticity in glassy polymers, and they are in agreement with the pseudocrosslinking concept of antiplasticization. By comparing the antiplasticization behavior of PVC/PCL blends with that of PVC/DOA and PVC/DOS from reported data, it was possible to obtaing an idea of the level of compatibility in the PVC/PCL blends. The results suggest that PCL is partially compatible with PVC.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 1337-1346 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transport behavior of O2 and N2 were studied for series of physical blends of PVC with EVA having different vinyl acetate (VAc) contents in the EVA (45 and 65 wt-%) and using different milling temperatures (160° and 185°C). The polymer blends were further characterized by dynamic mechanical measurements, density measurements, and x-ray diffraction. At higher VAc content in EVA and with higher milling temperature, the rate of permeation (P) and the rate of diffusion (D) decrease, and the activation energy of D (from Arrhenius plots) increases. Furthermore, the experimental density values of PVC/EVA-45 blends agree well with calculated values, assuming volume additivity of the two components, while those of PVC/EVA-65 blends are higher than the calculated densities. These results are interpreted as due to denser packing of polymer molecules and increased PVC-EVA interaction at higher VAc content and with higher milling temperature, indicating better compatibility between the blend components. The x-ray diffraction data give no evidence of crystallinity. Sharp increases in P and D values at about 7.5% EVA (by weight) are found for PVC/EVA-45 blends (in agreement with our previous work) but not for PVC/EVA-65 blends. This is interpreted as due to a phase inversion at increasing EVA content in the former blends but not in the latter blends. The dynamic mechanical measurements show that the PVC/EVA-65 blends milled at 160°C behave largely as semicompatible systems with maximum interaction between the two polymers at compositions of about 50/50 by weight.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 2143-2155 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transport behavior of He, O2, N2, and CO2 in a series of PVC/NBR polymer blends with varying acrylonitrile (AN) content in the NBR component has been studied at 25° and 50°C. In addition, measurements of density, crystallinity, and thermal expansion coefficients were carried out. The transport behavior of these blends is similar to previous result for PVC/EVA.1. With increasing AN content in NBR, the permeability (P) and diffusivity (D) of the permeants decreased while the activation energy for diffusion (ED) increased. For the polymer blends, better additivity of permeability and diffusivity was observed with increasing AN content in the NBR component. The polymer blends also showed increasing volume contraction with increasing AN content in the NBR component. These effects have been discussed as due mainly to increased polymer-polymer interaction causing reduced segmental mobility and increased compatibility of the two polymers. The sorption values calculated from P/D ratios were largely irregular and fluctuated with the blend composition. They were less reproducible than other transport parameters, i.e., P and D measured separately. Several reasons for the irregular sorption behavior were proposed.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 3105-3119 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The permeability P, diffusivity D, and activation energy for diffusion, ED, of He, O2, N2, and CO2 were determined for blends of PVC/chlorinated polyethylene (CPE), where the chlorine content of the CPE components varied: 36 wt-% for CPE-1, 42 wt-% for CPE-2, and 48 wt-% for CPE-3. The difference in thermal expansion coefficients Δα above and below the glass transition temperature Tg of the polymers and the fractional free volume Vg of the polymers at their Tg were determined. Density and crystallinity measurements for the blends were also carried out as in the earlier work (Shur and Rånby, J. Appl. Polym. Sci., 19, 1337 (1975)). Dynamic mechanical measurements of the blends were made using a torsion pendulum at about 1 Hz. P and D decreased, but ED increased with increasing CI content of CPE in the blends. P and D for the blends showed no additivity. The permeability indicated phase inversion for blend compositions at about 10% of CPE-1 and CPD-2 by weight. The experimental and the calculated densities were largely the same for PVC/CPE-1 blends; but for PVC/CPE-2 and PVC/CPE-3 blends, the experimental values were higher than the calculated ones. The Δα and Vg values for PVC and the three CPE samples decreased with increasing CI content in the polymers. Dynamic mechanical measurements indicate that PVC/CPE-1 and PVC/CPE-2 blends form largely incompatible blends, while PVC/CPE-3 blends are compatible to some extent. There is some weak interaction between PVC and CPE-3 giving a low level of compatibility. The solubility of gases obtained from time-lag measurements of diffusion for 50/50 blends decreased for He, O2, and N2, but increased for CO2 with increasing Cl content in CPE. The solubility of He, O2 and N2 shows a positive correlation with the Lennard-Jones force constant ∊/k. However, a deviation from the linear relation between ∊/k and In S was observed for CO2 and the deviation became larger with increasing Cl content in CPE. The abnormally high solubility of CO2 is probably due to the high polarizability of this gas. The heat of solution ΔHs indicates that for He the sorption process may be a molecular slip process (endothermic), but for other gases the sorption may proceed by a dissolution process (exothermic). There is a large difference between the calculated solubility for the blends assuming incompatibility and the experimental values from time-lag measurements. This may partly be due to the uncertainty of sorption values obtained from the time-lag method and/or partly to changes of sorption modes by interaction between PVC and CPE in the blends. The resulting transport behavior of the blends is discussed on the basis of the free volume concept and of phase-phase interaction in the blends.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 943-946 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of polymer blends of commercial poly(vinyl chloride) (suspension-polymerized powder) and an ethylene-vinyl acetate copolymer (EVA with 45 wt % VA) containing 2-10 wt % EVA were prepared by mixing at room temperature (0) and by milling at 160°C for 15 min (I) and then heat treated at 170°C for 20 min (II) and 40 min (III). Wide-line NMR measurements for protons at room temperature show a broad band (assigned to PVC phase) and a superimposed narrow band (assigned to mobile EVA phase). The 0-samples had a narrow band intensity corresponding to the total EVA content; the I-samples had a less intense narrow band than expected, indicating that 2-3% EVA was included in the rigid PVC phase. Heat treatment for 20 min (II) and 40 min (III) increased the narrow band intensity toward the 0-samples showing phase separation except for milled blends containing 2 wt % EVA, which had no separable narrow band and remained so. These results indicate that about 2 wt % EVA is compatible with the PVC phase and in equilibrium, while milled blends with more than 2 wt % EVA are metastable.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2953-2961 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of PVC/NBR blends with varying acrylonitrile (AN) content in the NBR has been studied in uniaxial tension creep tests. The tests have been carried out at 21.5 ± 0.5°C covering creep times from 10 to 1000 sec. NBR with low AN content, having poor compatibility with PVC, gives the blends with higher compliance and increased time dependence of the compliance. A higher AN content in the NBR gives the blends with the opposite properties when the NBR is added in small amounts. NBR with 40 wt-% AN is found to act as an antiplasticizer giving minimal creep compliance when 7 wt-% NBR is added. The antiplasticization reveals a considerably increased stress level at which the transition from approximatively linear to marked nonlinear viscoelasticity occurs and a decreased stress dependence of the creep compliance in the nonlinear viscoelastic range. Since the antiplasticization is also associated with a suppression of the β-transition mechanism, the results provide a demonstration of the importance of β-mechanism in the stress activated processes responsible for the appearance of nonlinear viscoelasticity in solid polymers.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The molecular structure of interfaces formed by curing the polyamic acid of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) against copper and gold substrates was determined using surface-enhanced Raman scattering (SERS) and reflection-absorption infrared spectroscopy (RAIR). It was found that acid groups of the polyamic acid reacted with metal ions on the substrates to form carboxylate salts when the polyamic acid was spin-coated onto metal substrates. Formation of carboxylates on the copper surface extended several hundred angstroms into the polyamic acid films, while only trace levels of carboxylate were formed on the gold surface. Formation of carboxylate salts suppressed the curing of polyamic acid on copper substrates. However, the degree of curing of the polyamic acid was high on gold surfaces. These results were compared to our previous work concerned with the molecular structure of interfaces between PMDA/ODA polyimides and silver substrates. The extent of carboxylate formation on silver was intermediate between those on copper and gold. Results obtained from SERS and RAIR also indicated that cured polyimide films above the partially cured layers were oriented edge-on, with the PMDA moieties perpendicular to the metal surface and the ODA moieties mostly parallel to the surface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 448-456 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Surface-enhanced Raman scattering (SERS) is an analytical technique in which the Raman scattering cross-sections of molecules absorbed onto the roughened surfaces of certain metals are enhanced by as much as six orders of magnitude compared to their value for normal Raman scattering. The mechanisms are associated with the large electric fields that can be induced at the surfaces of metal particles having small radii of curvature and with the formation of charge-transfer complexes between the adsorbed molecules and the substrate. Enhancement due to the charge-transfer mechanism is obtained only for molecules immediately adjacent to the surface, but enhancement due to the electromagnetic mechanism may extend several monolayers away from the surface. Since normal Raman scattering by polymers is weak and scattering by molecules adjacent to the substrate is strongly enhanced, SERS can be used for non-destructive characterization of interfaces between polymer films and metals as long as the films are not so thick that scattering by the bulk of the film is comparable in intensity to SERS from the interface.We have used SERS to examine the interface between silver and an acrylic adhesive system consisting of an acrylic monomer and a cure system comprising cumene hydroperoxide (CHP), acetylphenylhydrazine (APH) and saccharin. SERS spectra obtained from films of the adhesive spin-coated onto silver island films were similar to normal Raman spectra of salts of saccharin, indicating that saccharin had adsorbed on the silver dissociativly. The spectra were independent of the thickness of the adhesive films, indicating that the SERS signal was characteristic of the interface and not of the bulk adhesive.SERS has been used also to characterize the interface between silver and pyromellitic diimide (PMDI), a model compound for polyimides. SERS spectra of PMDI adsorbed onto silver were considerably different from normal Raman spectra. The strongest band in the normal spectra, a carbonyl stretching mode near 1770 cm-1, was absent from the SERS spectra and a band near 700 cm-1, which was very weak in normal Raman spectra, was strong in SERS spectra. It was concluded that PMDI was adsorbed in a vertical conformation with one imide group adjacent to the surface.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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