ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Hybrid biomaterials prepared by ozone-induced polymerization. I. Ozonation of microporous polypropylene (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1461-1467 
    Details
    ISSN: 0887-624X
    Keywords: hybrid biomaterials ; grafting ; hydrogek ; membranes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We employed an ozone-induced grafting process to prepare membrane-hydrogel hybrid biomaterials. Exposure of isotactic polypropylene to ozone resulted in surface oxidation, as detected by ESCA, and the formation of peroxides and hydroperoxides. The amount of oxygen-bearing moieties, as detected by FT-IR, was increased when a microporous membrane with a large surface area was used. Ozonation for an extended period of time, 1-2 h, resulted in a degradation of microporous PP, observed with SEM as an enlargement of pores and brittle characteristics of the material. The molecular weight of PP was dramatically reduced after as little as 5 min of ozonation. Exposure to ozone for longer periods of time contributed to further reductions of the molecular weight and gradual modification of chemical composition of polypropylene, restricted, however, to the surface or intercrystalline amorphous regions. It was possible to graft 2-hydroxyethylmethacrylate (HEMA) to the ozonated samples, such that the graft copolymer acted as continiuous matrix consequently linked to and reinforced by the PP crystals. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1461-1467, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Crosslinked poly(hydroxyethyl methacrylate) membranes for desalination by reverse osmosis (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 14 (1970), S. 1339-1359 
    Details
    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 crosslinked hydroxyethyl methacrylate (HEMA) membranes for reverse osmosis desalination has been prepared. The crosslinkers used were trimethylol propane trimethacrylate (TPT) or ethylene glycol dimethacrylate (EGD). Membranes were synthesized by polymerizing the monomers as a thin homogeneous film. In addition to reverse osmosis tests, the membranes were also characterized by osmosis experiments and sorption measurements. The reverse osmosis water flux (1500 psi applied pressure, 4% NaCl brine, pH = 5) for these membranes decreases from 0.6 gallonmil/ft2-day (GMFD) to 0.055 GMFD and salt rejection increase from 78% to a maximum of 94% as the amount of TPT is increased from 0 to 11 mole-%. Water contents decrease from 42% to 15% over the same range of crosslinker, but the preferential sorption of water to salt does not vary. Thus, rises in reverse-osmosis semipermeability were found to result from changes in water-salt diffusivity ratios. The mechanism of permselectivity has been interpreted in terms of parallel diffusive fluxes across the membrane of primary H-bonded water and secondary water plus salt ions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1970.070140519
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Immobilization of poly(ethylene oxide) on poly(ethylene terephthalate) using a plasma polymerization process (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 91-107 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(ethylene oxide) (PEO) has been covalently immobilized on poly(ethylene terephthalate) (PET) films using a radio frequency glow discharge polymer deposition process, followed by chemical coupling. Amino or hydroxyl groups were introduced onto the surface of the PET by exposing the films to allylamine and allyl alcohol plasmas. These functional groups were activated with cyanuric chloride, and then they were reacted with PEO. ESCA and water contact angle studies were used to characterize the surfaces of these films during the different stages of the reaction. The films containing the higher molecular weight PEO exhibited an increase in the —C—O— peak of the Cls ESCA spectrum and an increase in oxygen content on the film surfaces. Increasing the molecular weight of the PEO attached to the PET also resulted in an increased wettability of the films.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370108
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The permeability of some graft copolymers of polyethylene to gases and vapors (1960)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 4 (1960), S. 159-165 
    Details
    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: Graft copolymers of polyethylene were prepared by gamma irradiation of polyethylene films immersed in the appropriate monomer. The majority of gas permeability measurements were made by Barrer's high vacuum technique; others were made by measuring volumetric change as a function of time. Sorption isotherms were obtained by using a quartz helix microbalance. Temperature dependent permeability constants have been obtained for permeation of oxygen, nitrogen, and carbon dioxide through styrene, acrylonitrile, and vinylpyridine grafted to low-density polyethylene. Permeability constants at 25°C. have also been determined as a function of water vapor partial pressure for the above systems. Some values for permeation of carbon dioxide through styrene grafted to high density or linear polyethylene are also given. Organic vapors studied were methyl bromide and isobutene, permeability constants at 0°C. being determined for styrene and acrylonitrile-polyethylene graft copolymers as a function of organic vapor pressure. The data show clearly that permeation through acrylonitrile and vinylpyridine-polyethylene grafts is primarily a diffusion process, while in permeation through polyethylene-styrene grafts, there is also a crystallite solution effect. Percentage grafts varied from 0 to 100 parts monomer per 100 parts by weight polyethylene.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1960.070041104
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Characterization of branched polyethylene fractions from the elution columnThis paper is assigned No. TP432 in the series of papers approved for publication by the U.S. Army Natick Laboratories. (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 1567-1587 
    Details
    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: Fractions from several elution column runs on samples of up to 6 g. of a well-characterized high-pressure polyethylene were analyzed by absolute molecular weight methods and several other techniques. The Mn and Mw integral distribution curves are free from any reversal, as was the viscosity distribution curve. Fractions with Mw as high as 8 × 106 were recovered, more than 20 times higher than the original sample's Mw. The polydispersity of the fractions increases from Mw/Mn = 1.5 or less in the low molecular weight fractions to a nearly constant value of 4.5-5.0 in fractions above 60% cumulative sample weight. Nonetheless, refractionation on the elution column shows that the fractions are narrowly distributed in terms of solubility, while GPC analysis reveals that the fractions have an extremely narrow size distribution. It is concluded from the combined results that long-chain branching plays an important role in determining the equilibrium solubility and, further, that long-chain branching increases the polymer solubility. Sample calculations are provided, which illustrate the effect of fraction polydispersity on calculated original sample molecular weights and the fit of the fractionation results to several model distribution functions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1968.070120708
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Elution column fractionation of branched polyethylene (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 509-525 
    Details
    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: In a systematic study of the elution column fractionation of a well characterized branched polyethylene sample it was found that one of the most important factors contributing to the efficiency was the composition selected for the p-xylene-butyl cellosolve eluting mixture. With a mixture representing the critical solvent composition at 126°C., as determined by cloud point measurements, and deposition to an amorphous phase on a fine sand support, viscosity-distribution curves were obtained which were highly reproducible and completely free of any reversal. No further improvement was gained by using an elution temperature other than 126°C. or by the substitution of tetralin or mesitylene for p-xylene. Precipitation down a temperature gradient to produce a physical separation of species provided enhanced fractionation but is of doubtful practical interest. Fractionation was readily scaled up from 2g. to 4 or 6g., merely by increasing the mixing vessel size from 500 cc. to 1000 cc. There was no loss of efficiency, and fractions with M̄w = 8 × 106, more than twentyfold higher than the sample value, were obtained despite eluted polymer concentrations exceeding 0.2%. There is evidence that many of the expected differences in the fractionation behavior of linear and branched polyethylene are erased when a solvent mixture is used which has been adjusted to the appropriate critical composition.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1968.070120310
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The kinetics of baboon fibrinogen adsorption to polymers: In vitro and in vivo studies (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 739-772 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fibrinogen adsorption on polymers from blood may mediate or potentiate thrombosis because of its involvement in both the intrinsic clotting system and the formation of platelet aggregates. While the kinetics of fibrinogen adsorption from plasma in vitro have previously been found to be very different on polar and nonpolar surfaces [T. A Horbett, “The kinetics of adsorption of plasma proteins to a series of hydrophilic-hydrophobic copolymers,” ACS Org. Coat. Plas. Chem., 40, 642-646 (1979)] the significance of this difference with respect to thrombogenesis in vivo has not been clarified. In this study, the kinetics of deposition of baboon 125I fibrinogen from plasma in vitro or from blood in vivo on a series of polymers was measured. The polymers chosen for this study had previously been found to have a large range in surface polarity and reactivity in the in vivo baboon shunt model. The kinetics of fibrinogen adsorption in vitro were observed to be of three types, depending on the polymer: (1) high initial adsorption decreasing to a lower steady state value; (2) constant throughout the time course; (3) low initial adsorption rising steadily to a plateau value. In vivo, fibrinogen deposition kinetics were of two types: (1) low, constant deposition throughout the time course, independent of heparinization; (2) low deposition initially followed by a second phase of greatly increased deposition (probably as fibrin) which was prevented or greatly decreased by heparinizing the animals. Polymers for which fibrinogen adsorption increased to a plateau in vitro were found to have a heparin inhibitable second phase of enhanced in vivo fibrinogen deposition. These polymers also have been found in previous studies to enhance the rate of platelet destruction when used as in vivo shunts on baboons. Conversely, most polymers with high initial in vitro fibrinogen adsorption followed by a decrease had low fibrinogen deposition behavior in vivo and were also minimally destructive of platelets. The adsorption kinetics of fibrinogen to polymers from blood in vivo and in vitro and the consumption of platelets in vivo induced by the polymers all vary with polymer polarity. More polar polymers had in vitro fibrinogen kinetics characterized by a rise to a plateau, in vivo fibrinogen deposition characterized by a second stage of great increase inhibitable by heparin, and enhanced platelet consumption. The correlation of three separate indicators of surface thrombogenicity with surface polarity suggests that more polar materials may be more thrombogenic because of an influence on the way in which fibrinogen interacts with these surfaces.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200608
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Cell adhesion to a series of hydrophili-hydrophobic copolymers studies with a spinning disc apparatus (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 383-404 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Adhesion of cells to substrates strongly influences many of their functions and therefore plays an important role in a variety of processes, including phagocytosis, hemostasis, and the response of tissue to implanted materials. In previous studies, the influence of substrate hydrophilicity on cell adhesion has not been separated from effects due to major differences in other properties of the substrate, such as charge, rigidity, and the specific chemical composition of the materials. In addition, very few careful studies of the force required for cell detachment from various substrates have been performed. In this study, 3T3 cell detachment from a chemically homologous series of copolymers based on hydroxyethylmethacrylate (HEMA) and ethylmethacrylate (EMA) was measured with a spinning-disc apparatus. The spinning-disc technique allowed measurements of cell detachment over a wide range of applied shear stress on each sample. Cell detachment did not occur until a critical value of shear stress was exceeded. The critical shear stress of detachment decreased linearly with increasing HEMA content, from 18 dynes/cm2 on poly-EMA to 0 on the polymers containing 83% or more HEMA. “Plating efficiency,” calculated as the fraction of cells initially applied which remained after dip rinsing the surfaces, did not vary significantly among most of the copolymers. Dip rinsing, however, exposes the cells to only one, relatively low shear stress (estimated to be somewhat less than 3 dynes/cm2). The existence of a critical shear stress for 3T3 cell detachment suggests that cell adhesion to surfaces cannot be fully understood with single shear stress methods because cells may attach with a wide range of strengths which are either all above or all below the applied shear stress. The influence of surface hydrophilicity on cell adhesion and the variety of forces which may contribute to this phenomenon are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820220503
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Extended fine structure in the secondary electron emission spectra of graphite and glassy carbon (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 590-593 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron excited secondary electron emission (SEE) spectra of highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC) were measured in the 0-150 eV electron kinetic energy range.For HOPG, the SEE spectrum was measured as a function of primary electron beam energy above and below the threshold for carbon core level 1s ionization. The SEE spectrum in the 0-70 eV range reflects high energy conduction band states, in agreement with band structure calculations and other spectroscopic techniques sensitive to the empty density of states. For electron kinetic energies above ∼ 70 eV the spectrum of HOPG displays a well defined structure which has not been studied previously. We found that the SEE fine structure in the low energy range up to ∼ 40 eV shows some dependence on primary electron energy, whereas for larger energies a much weaker dependence was found. It has been established that the SEE spectrum is strongly affected by low-energy Ar ion irradiation of the HOPG surface. This result suggests that the SEE spectrum is very sensitive to crystal defects induced by the irradiation process. The lower-energy range of the spectrum, up to ∼ 40 eV was found to be more sensitive to damage induced by the ion irradiation process than the higher range of the spectrum.For GC, the SEE spectrum in the 0-50 eV range is smeared out compared to that of HOPG. However, in the higher electron kinetic range some of the peaks measured for HOPG were also observed for GC. These results suggest that the lower-energy range of the SEE spectrum is more sensitive to long-range order, whereas the higher-energy range of the spectrum reflects a shorter-range order. It is suggested that SEE spectroscopy can be used as a very sensitive tool for the characterization of different carbon structures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.7402201125
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Irradiation effects induced by reactive and non-reactive low energy ion irradiation of graphite: An electron spectroscopy study (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 524-527 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The effect of low energy Ar+ and N2+ irradiation of highly oriented pyrolytic graphite (HOPG) has been investigated by AES and XPS. Based on measurements of the C(KVV) Auger line shape before and after irradiation it has been found that a high degree of structural disorder is induced in the near-surface region of HOPG. The production of defects induced by the irradiation process was established by the appearance of a shoulder at the high energy side of the C(KVV) Auger line. After Ar+ irradiation the shoulder is well defined and clearly visible in the Auger spectrum. However, after N2+ irradiation this shoulder is broader and its intensity is smaller than that observed after Ar+ irradiation. It is suggested that the defects created during the N2+ irradiation process are partly compensated by chemical bonding between implanted nitrogen and displaced carbon atoms. XPS measurements confirmed the existence of chemical bonds formed between the implanted nitrogen and carbon atoms.The effect of thermal annealing of the irradiated graphite was investigated up to 500 °C. At temperatures as low as 100 °C a decrease of the shoulder intensity was observed, whereas the desorption of the implanted Ar occurs at 300-400 °C only. These results suggest that the defects created by Ar+ irradiation are partially annealed. For N2+ irradiation, some nitrogen desorption occurs accompanied by a broadening and splitting of the N(1s) core-level line. Also in this case, the shoulder intensity decreases with increasing the annealing temperature. It is suggested that partial annealing of the nitrogen-implanted layer takes place. These results are of relevance for the understanding of the basic processes occuring during deposition of carbon nitride thin films by ion beam-assisted methods.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.7402201111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...