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  • Polymer and Materials Science  (2,912)
  • 2010-2014
  • 1990-1994  (1,705)
  • 1980-1984  (1,207)
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  • 1
    Electronic Resource
    Electronic Resource
    Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers III: Surface and bulk compositional differences (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 547-571 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previously observed bioactivity of poly(dimethylsiloxane)-poly(ethyelene oxide)-heparin (PDMS-PEO-Hep) triblock copolymers has prompted studies of the surface and bulk character of this copolymer using angular-dependent electron spectroscopy for chemical analysis (ADESCA), static secondary mass spectroscopy (SIMS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Because the low-energy PDMS phase dominates surfaces of this copolymer when solvent cast under air or vacuum conditions, attempts were made to explain surface restructuring and rearrangements induced in hydrated or aqueous environments that permit surface accessibility and bioactivity of heparin moieties. Based on comparisons with PDMS, PEO, and heparin homopolymers, PEO/heparin blends, and an unheparinized PDMS-PEO diblock copolymer, PDMS-PEO-heparin demonstrates both phase-mixed and phase-separated regions in DSC analysis. During annealing cycles above the Tg values of the copolymer constituents, phase-mixed regions become increasingly phase separated and PEO enriched. TGA analysis confirmed the presence of block copolymer constituents and presented evidence of intermolecular segmental interactions, hence phase-mixing in the copolymers. ADESCA analysis indicates that the outer 5 Å of both the PDMS-PEO and PDMS-PEO-Hep copolymers is essentially pure PDMS. However, significant amounts of PEO are detected 5 to 20 Å below the surface. Static SIMS also detects the presence of PDMS at the surfaces of the PDMS-PEO and PDMS-PEO-Hep copolymers. Compositional models based on ADESCA, SIMS, and DSC data are presented for desiccated and hydrated copolymer surfaces.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820240503
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  • 2
    Electronic Resource
    Electronic Resource
    Model filled polymers. I. Synthesis of crosslinked monodisperse polystyrene beads (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1909-1921 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monodisperse crosslinked polystyrene beads of varied size and crosslink density are prepared by emulsion copolymerization of styrene and divinylbenzene in the absence of emulsifier. Tumbling and internally stirred reactors were used for synthesis, with minimal agglomeration at at least 0.22 wt % potassium persulfate and up to 10% by weight of styrene in aqueous emulsion in the absence of oxygen. Particle sizes decreased from 800 to 200 nm on raising the polymerization temperature from 60 to 95°C. The glass transition temperature of the beads increased from 104.4 to 133°C by the inclusion of up to 10% by weight of divinylbenzene. The thermal stability of the beads was higher for peroxide than for persulfate initiation. The crosslink density estimated from the degree of swelling was about one third that expected from stoichiometry. The polystyrene beads are used as filler particles in polymer composites.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280722
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  • 3
    Electronic Resource
    Electronic Resource
    Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 277-283 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFT15), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFT15 material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFT15 had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFT15. The final conclusion is that in this model, grafting with COLLAGRAFT15 provided torsional properties at one year postoperatively at least equivalent to autogenous bone. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050402
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  • 4
    Electronic Resource
    Electronic Resource
    The influence of charge density and steric factor of aminated chloromethyl polystyrene homologs in bilirubin adsorption (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 2483-2488 
    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: Bilirubin, a bile pigment, was studied for its extent of adsorption on substituted aminechloromethyl polystyrene by UV spectrophotometry. By performing simple displacement reactions on chloromethyl polystyrene with secondary and tertiary amines, the amount of charge density and steric factor on substituted nitrogen atom have been varied. Adsorption isotherms of bilirubin at 0°C by different amine-chloromethyl polystyrene homologs suggest the existence of electrostatic interaction of polymeric resin with bilirubin moiety. Results of adsorption of bilirubin to polymeric resin have shown that the extent of adsorption of bilirubin depends on the unit charge, and on the structure of the substituted amine-chloromethyl polystyrene. The effects of porosity of resin on bilirubin adsorption have also been discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420913
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  • 5
    Electronic Resource
    Electronic Resource
    Diffusion-adsorption problems in macromolecular systems: New techniques for parameter estimationNCL Communication No. 4534. (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 769-783 
    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: It has been shown that the techniques used for estimation of diffusion-adsorption parameters in the past have certain basic flaws. New and efficient techniques for parameter estimation have been proposed. These have many advantages such as using the full concentration-time profile (rather than part of it), time saving, etc. The validity of these techniques has been demonstrated by the analysis of the data generated in our laboratory on adsorption of polyacrylamide and also the data on adsorption of dyes on chitin reported in the literature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390401
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  • 6
    Electronic Resource
    Electronic Resource
    Crystallinity and lateral crystallite size of different UHMW PE materials (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 863-866 
    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: Nascent high-molecular-weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70-75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15-25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower-molecular-weight PE samples and for high-strength / modulus PE fibers of different origins.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420332
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  • 7
    Electronic Resource
    Electronic Resource
    Ionomers as charge additives (1990)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 28 (1990), S. 75-80 
    Details
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contract electrification measurements were performed on polymeric particles containing toluenesulfonate salt. Two forms of the toluenesulfonate ion pair were studied, an ionomer, poly(styrene-co-N-methyl-4-vinylpyridinium toluenesulfonate) and a molecular salt, cetyltrimethylammonium toluenesulfonate. Both types of particles charge positive, and the ionomer produces the higher charge level. XPS analysis shows that the particles containing the ionomer have a surface salt composition that resembles the formulation composition, whereas the surface salt composition of the particles containing the molecular is significantly higher than in the formulation. The variation in the surface ion concentration is used to estimate a relative charging capacity of the salts. XPS analyses of the carriers that were used with both particles shows an S 2p signal appropriate for the toluenesulfonate anion. A mechanism for charging involving the transfer of the toluenesulfonate anion from polymer particles to the carrier is proposed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1990.140280301
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  • 8
    Electronic Resource
    Electronic Resource
    Deterioration of plastic films under soil burial conditionsIssued as N.R.C.C. # 18807. (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 509-519 
    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: The deterioration of polyolefin, poly(ethylene terephthalate), and polyamide films under soil burial conditions extending up to 32 months has been investigated. Based on changes in their elongation at break, the films can be ranked in order of increasing sensitivity to degradation: Polyester ≃ polypropylene 〈 low-density polyethylene ≃ high-density polyethylene 〈 nylon 6.6. The degraded nylon 6.6 and polyethylene films were characterized by infrared and luminescence spectroscopy and scanning electron microscopy, as well as by wet analysis for hydroperoxides. From a comparison with the well-known oxidative sensitivity of nylon 6.6 in oxygenated water at slightly elevated temperatures, the rapid deterioration of nylon 6.6 film during soil burial was also concluded to be an oxidative process. The somewhat smaller, but significant, embrittlement of the polyethylenes studied could not be simply explained by thermal oxidation (with only trace oxidation products detectable) or microbiological attack (deterioration being unaffected by surface activation to enhance wettability).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260211
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  • 9
    Electronic Resource
    Electronic Resource
    Metal ion concentrations in retrieved polyethylene total hip inserts and implications for artifactually high readings in tissue (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 1349-1355 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although there are many studies which document high metal ion concentrations in clinically retrieved tissues surrounding total joint replacements, most investigations have remained cautious in their interpretation due to the artifactual influences of metal particulate.The possible contribution of polyethylene wear debris to artifactually high periprosthetic metal ion concentration readings has not been previously considered. This study documents the potential role of polyethylene particulate contamination in causing artifactually high metal concentration readings in tissues.The data showed metal ion contamination in the polyethylene was progressive at each stage of exposure to metal: from bar stock preparation, to manufacturing, to in vivo ambulation. The manufacturing and machining processes showed a statistically significant (P ≤ .05) increase in metal ion concentrations in the nonarticulated acetabular inserts over bar stock.The results of this study demonstrate that periprosthetic tissue and synovial fluid metal ion concentration data must be interpreted with caution due to possible artifactual problems associated with metal ion contaminated polyethylene particulate. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820271102
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  • 10
    Electronic Resource
    Electronic Resource
    Blood-materials interactions: The minimum interfacial free energy and the optimum polar/apolar ratio hypotheses (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 381-398 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Numerous hypotheses exist to explain observed blood-materials interactions. It is the purpose of this article to test two popular hypotheses, namely, the minimum interfacial free energy hypothesis and the optimum polar/apolar ratio hypothesis. Methacrylate polymers and copolymers were characterized using the captive bubble underwater contact angle method; bulk water content was determined by gravimetric methods; streaming potential measurements were made; and surface roughness and possible particulate contamination were evaluated by reflected light microscopy. In vitro blood tests include whole blood clotting time measurements on polymer-coated tubes; centrifugal force platelet adhesion on polymer-coated coverslips; and a measure of the partial thromboplastin time, Russell's viper venom time (Stypven time), and the prothrombin time of native whole blood exposed to polymer-coated microscope slides. Results suggest that platelet adhesion correlates in the opposite direction of whole blood clotting time and partial thromboplastin time, emphasizing the need for a multiparameter approach to blood-materials testing. Based on these tests the minimum interfacial free energy hypothesis is not supported. In fact, the data suggest the opposite to be true. It is apparent that platelet adhesion can be a misleading indicator of blood compatibility. Neither hypotheses can explain the apparent conflict between the platelet adhesion data and the coagulation time data.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160407
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