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  • 1
    Electronic Resource
    Electronic Resource
    Surface modification and adhesion characteristics of polycarbonate films after graft copolymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 357-366 
    Details
    ISSN: 0887-624X
    Keywords: surface graft copolymerization ; adhesive-free adhesion ; polycarbonate ; XPS ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surfaces of ozone-pretreated polycarbonate films were subjected to further modification by thermally induced graft copolymerization with acrylic acid (AAc), sodium salt of styrene sulfonic acid (NaSS), N,N-dimethylacrylamide (DMAA), N,N-(dimethylamino)ethyl methacrylate (DMAEMA) and 3-dimethyl(methacryloyl ethyl)-ammonium propanesulfonate (DMAPS) monomers. The structure and composition at the copolymer interface were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). For polycarbonate films with a substantial amount of grafted polymer, the hydrophilic graft penetrates or becomes partially submerged beneath a thin surface layer of dense substrate chains. This microstructure was further supported by the water contact angle measurements. Adhesive-free adhesion studies revealed that the AAc, DMAA or DMAPS graft copolymerized polycarbonate film surface adhered strongly to another similarly modified surface (homo-interface) when brought into direct contact in the presence of water and subsequently dried. The development of the lap shear strength is dependent on the concentration of the surface graft, the microstructure of the grafted surface, the adhesion (drying) time, and the nature of the interfacial interaction. The simultaneous presence of chain entanglement and electrostatic interaction readily results in substantially enhanced adhesion strengths between two DMAPS graft copolymerized surfaces or between an AAc and a DMAA graft copolymerized surface (hetero-interface). XPS analyses of the delaminated surfaces suggest that failure occurred cohesively below the graft-substrate interface. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 357-366, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Fracture of tendon collagenPaper presented at the Symposium on Mechano-Chemistry of Polymers, American Chemical Society National Meeting, Washington, D.C., September 16, 1971. (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 577-584 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of rat-tail tendon fibers, about 200 μ in diameter, by scanning electron microscopy of fractured specimens reveals that these crimped fibers are largely made up of cylindrical units, about 10 μ in diameter. These, in turn, are made up of the well-known collagen fibrils, ca. 0.1 μ in diameter, which have been observed previously by transmission electron microscopy and small-angle x-ray diffraction. Both the 10-μ and 0.1-μ cylindrical units were found to be arranged parallel to the macroscopic fiber axis rather than helically about it, as has been often proposed in the past. Significant improvement in resolution of the fracture surfaces was obtained by dehydration of the tendon. Microscopy of undehydrated tendon fibers undergoing solubilization by dilute aqueous acetic acid confirmed the results obtained by fractography.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100401
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of measurements of the viscoelastic properties of polymer melts by means of the Han slit/capillary rheometer and the Weissenberg rheogoniometer (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 95-103 
    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: Measurements were taken of the viscoelastic properties of six polymer melts by mean of the Weissenberg rheogoniometer and the Han slit/capillary rheometer. Polymers in vestigated were three high-density polyethylenes of different polydispersity, a low-density polyethylene, a polypropylene, and a polystyrene. The range of shear rates tested was from about 5.0 × 10-3 to 10 sec-1 with the Weissenberg rheogoniometer, from about 10 to 102 sec-1 with the slit rheometer, and from about 102 and 103 with the capillary rheometer: the temperature of measurement was 200°C. The three different apparatuses give consistent results over almost six decades of shear rates, yielding satisfactory correlations of shear viscosity to shear rate and of normal stress difference to shear rate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170107
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  • 4
    Electronic Resource
    Electronic Resource
    Correlation of in vivo collagen degradation rate with in vitro measurements (1975)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 623-628 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The rate of in vitro enzymatic degradation of various materials based on collagen has been determined by a novel mechanochemical method, and has been compared with the extent of degradation resulting from subcutaneous implantation in guinea pigs. In vitro data correlate well with in vivo data. It is suggested that the simple in vitro method described is an effective means of screening a large number of materials based on collagen for their ability to resist degradation during implantation in animals.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820090608
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  • 5
    Electronic Resource
    Electronic Resource
    Design of an artificial skin. II. Control of chemical compositionPart I of this series appears in J. Biomed. Mater. Res., 14, 65-81 (1980). (1980)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 107-132 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Detailed methodology is described for the reproducible preparation of collagen-glycosaminoglycan (GAG) membranes with known chemical composition. These membranes have been used to cover satisfactorily large experimental full-thickness skin wounds in guinea pigs over the past few years. Such membranes have effectively protected these wounds from infection and fluid loss for over 25 days without rejection and without requiring change or other invasive manipulation. When appropriately designed for the purpose, the membranes have also strongly retarded wound contraction and have become replaced by newly synthesized, stable connective tissue. In our work, purified, fully native collagen from two mammalian sources is precipitated from acid dispersion by addition of chondroitin 6-sulfate. The relative amount of GAG in the coprecipitate varies with the amount of GAG added and with the pH. Since coprecipitated GAG is generally eluted from collagen fibers by physiological fluids, control of the chemical composition of membranes is arrived at by crosslinking the collagen-GAG ionic complex with glutaraldehyde, or, alternately, by use of high-temperature vacuum dehydration. Appropriate use of the crosslinking treatment allows separate study of changes in membrane composition due to elution of GAG by extracellular fluid in animal studies from changes in composition due to enzymatic degradation of the grafted or implanted membrane in these studies. Exhaustive in vitro elution studies extending up to 20 days showed that these crosslinking treatments insolubilize in an apparently permanent manner a fraction of the ionically complexed GAG, although it could not be directly confirmed that glutaraldehyde treatment covalently crosslinks GAG to collagen. By contrast, the available evidence suggests strongly that high-temperature vacuum dehydration leads to formation of chemical bonds between collagen and GAG. Procedures are described for control of insolubilized and “free” GAG in these membranes as well as for control of the molecular weight between crosslinks (Mc). The insolubilized GAG can be controlled in the range 0.5-10 wt. % while “free” GAG can be independently controlled up to at least 25 wt. %; Mc can be controlled in the range 2500-40,000. Studies by infrared spectroscopy have shown that treatment of collagen-GAG membranes by glutaraldehyde or under high-temperature vacuum does not alter the configuration of the collagen triple helix in the membranes. Neither do these treatments modify the native banding pattern of collagen as viewed by electron microscopy. Collagen-GAG membranes appear to be useful as chemically well-characterized, solid macromolecular probes of biomaterial-tissue interactions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820140203
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanochemical studies of enzymatic degradation of insoluble collagen fibers (1977)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 137-154 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A mechanochemical method was developed for studying the enzymatic degradation of insoluble collagen fibers. The method involves stretching the collagen fiber to a fixed extension in the presence of a solution of collagenase and measuring the rate of relaxation of the force induced on the fiber. In this work, bacterial collagenase was used for reasons of availability. We observed invariably an exponential decrease in force with respect to time. The slope of the linear plot of logarithm of the force versus time was taken as a measure of the rate of enzymatic degradation. This rate was found (a) to vary linearly with collagenase concentration; (b) to be maximized at pH 7-8; (c) to vary with temperature according to the Arrhenius relationship in the range 10-56°C; (d) to be reduced to varying extent by addition of EDTA, o-phenanthroline, 2,3-dimercaptopropanol, and D, L-cysteine; (e) to be minimal when the strain on the fiber was ca. 4%; (f) to be increased dramatically by denaturation of the collagen fiber; and (g) to be reduced by an increase in the crosslink density of the collagen fiber. Except for the effect of strain, which can not be conveniently sudied by existing methods, these results are consistent with those observed by other methods for the study of the enzymatic degradation of collagen. The mechanochemical method is, however, uniquely suited to monitor continuously the enzymatically induced decay in the stress-bearing ability of collagen fibers. It has also been found useful in the design of collagenous implants with specified resistance to enzymatic degradation in vivo.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820110113
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of thermosetting hydrocarbon resin. Resins from formaldehyde, LXIII.The foregoing paper of thi5 series: Part LII, M. Imoto, C. Y. Huang, J. Hashizume, S. Sano, and K. Uiya, J. chem. SOC. Japan, ind. Chem. Sect. 63 (1960) 1807. (1961)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 43 (1961), S. 189-219 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Um ein „härtbares“ Harz zu erhalten, das nur aus Kohlenstoff und Wasserstoff besteht, wurde ein Xylol-Formaldehyd-Harz (XF-Harz) mit einem Kohlenwasserstoff (CH) wie folgt umgesetzt: Es wurde dabei angenommen, daß hierbei eine elektrophile Substitution erfolgt. Auf der Suche nach reaktionsfähigen Kohlenwasserstoffen wurden 15 verschiedene aromatische Verbindungen in Gegenwart von Perchlorsäure mit Formaldehyd umgesetzt. Dabei reagierten Acenaphthen, Polyacenaphthylen, Anthracen und Mesitylen leicht mit Formaldehyd. Es wurden nunmehr XF-Harze hergestellt und mit den erwähnten aromatischen Kohlenwasserstoffen umgesetzt. Dabei waren Acenaphthen, Polyacenaphthylen und Acenaphthen-Formaldehydharz besonders wirksam.Da ein ω,ω'-Dimethylol-XF-Harz bei der Umsetzung noch wirksamer als ein normales Harz sein sollte, wurde eine brauchbare Methode für die Herstellung eines ω,ω'-Dimethylol-XF-Harzes entwickelt. Durch Umsetzung des ω,ω'-Dimethylol-XF-Harzes mit Acenaphthen-Formaldehyd-Harz in Gegenwart von Xylolsulfonsäure wurde schließlich ein gezielt vernetztes Harz erhalten, das nur aus Kohlenstoff und Wasserstoff bestand. Es ist unschmelzbar und in Benzol unlöslich.(Unter geänderten Bedingungen kann auch Anthracen oder Mesitylen das XF-Harz vernetzen).
    Notes: A study to obtain a resin consisting only of carbon and hydrogen and yet having thermosetting properties was made. The process was a reaction of xylene-formaldehyde resin (XF-resin) with a hydrocarbon (CH) The reaction was assumed to proceed through an electrophilic substitution. To find some reactive hydrocarbons, 15 different aromatic hydrocarbons have been reacted with formaldehyde in the presence of perchloric acid. It was found that acenaphthene, acenaphthylene, anthracene and mesitylene easily reacted with formaldehyde. Some XF-resins were prepared, and reacted with the mentioned aromatic hydrocarbons.Of these hydrocarbons, acenaphthene, polyacenaphthylene and acenaphthene-formaldehyde resin were especially effective.It is understandable that an ω,ω'-dimethylol-XF-resin is more effective than a normal XF-resin. So an useful method for the synthesis of the ω,ω'-dimethylol-XF-resin was investigated.By the reaction of ω,ω'-dimethylol-XF-resin with acenaphthene-formaldehyde resin in the presence of xylene sulfonic acid, the desired cured resin was obtained. The resin consisted only of carbon and hydrogen. It was insoluble in benzene and non-melting. (However, by changing the conditions, anthracene or mesitylene can also cure XF-resins).
    Additional Material: 32 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1961.020430121
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