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  • 1980-1984  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Influence of molecular weight on the dynamic mechanical properties of poly(methyl methacrylate) (1980)
    Springer
    Journal of thermal analysis and calorimetry 18 (1980), S. 117-126 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé En se servant d'un nouvel appareil à rayons parallèles, on a déterminé les propriétés mécaniques dynamiques du poly(méthyl-méthacrylate) dans un large intervalle de poids moléculaires (1500〈 $$\overline M _n$$ 〈600 000). Les résultats on montré que le module (25°) ne dépend que peu de la longueur de la chaîne et est égal à 2.3×109 Pa pour le plus haut poids moléculaire étudié. L'acquisition simultanée des relaxationsα etβ a indiqué, en accord avec la relation de Gibbs, une diminution deT α tandis queT β s'avere invariable. Les valeursT α ∞ =111°et}T β ∞ =40° ont corroboré toutes deux des résultats antérieurs de diverses sources, y compris des mesures mécanique dynamiques. Un tel module ainsi que les données de la transition vitreuse sont essentiels pour calculer la résistance à la rupture, et pour déterminer les dommages par irradiation des matières acryliques.
    Abstract: Zusammenfassung Unter Anwendung eines neuen Parallelstrahlgerätes wurden die dynamischen mechanischen Eigenschaften von Poly(methylmethacrylat) in einem weiten Molmassenbereich (1500〈 $$\overline M _n$$ 〈600 000) bestimmt. Die Ergebnisse zeigten, daß der Modul (25°) nur wenig von der Kettenlänge abhängig und für die höchste erfaßte Molmasse gleich 2.3× ×109 Pa war. Die gleichwertige Erfassung derα- undβ-Relaxationen zeigte in Übereinstimmung mit der Gibbs-schen Abhängigkeit eine Abnahme vonT α währendT β unverändert blieb. SowohlT α ∞ =111° als auchT β ∞ =40° bestätigten frühere Ergebnisse verschiedenen Ursprungs, dynamische mechanische Messungen mit inbegriffen. Solch ein Modul und Glas-Übergangsdaten sind zur Berechnung der Bruchfestigkeit bzw. zur Bestimmung der Bestrahlungsschäden in Acrylaten unerläßlich.
    Notes: Abstract Using a new parallel beam apparatus, the dynamic mechanical properties of poly-(methyl methacrylate) were determined over a wide range of molecular weights (1500〈 〈 $$\overline M _n$$ 〈600 000). Results showed that the modulus (25 °C) was only slightly dependent on chain length, and equalled 2.3×109 Pa for the highest molecular weight scanned. Simultaneous acquisition ofα- andβ-relaxations indicated a decrease inT α in accordance with Gibbs' relation, whileT β was invariant. BothT α ∞ =111° andT β ∞ =40° corroborated previous results from several sources, including dynamic mechanical measurements. Such modulus and glass transition data are essential to the calculation of fracture toughness and to the assessment of radiation damage of acrylic, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01909459
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamic mechanical properties of cross-linked poly(acrylic acid)-aluminum oxide composites (1980)
    Springer
    Journal of materials science 15 (1980), S. 3159-3162 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00550390
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of crosslinking on the glass transition of poly(acrylic acid) (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1785-1788 
    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
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250825
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  • 4
    Electronic Resource
    Electronic Resource
    Viscoelastic behavior of highly crosslinked poly(acrylic acid) (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 2795-2805 
    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 effects of crosslinking upon the dynamic mechanical properties and swelling behavior of poly(acrylic acid) (PAA) have been studied. Materials were prepared by the free radical copolymerization of acrylic acid with varying amounts of the tetrafunctional monomer allyl acrylate (ALA). The results indicated a linear dependence of the glass-transition temperature (Tg) on composition, Tg increasing by ∼43°C over the mole fraction range X = 0-0.37 ALA. Room temperature (25°C) modulus values, as determined by both dynamic and compression methods, were inversely proportional to the initial concentration of ALA. The degree of network formation has been characterized in terms of the molecular weight between crosslinks Mc, and the influence of this parameter on the swelling ratio was discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070251212
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  • 5
    Electronic Resource
    Electronic Resource
    Creep rupture behavior of polypropylene suture material and its applications as a time-release mechanismPresented in part at the Seventh Annual Meeting of the Society for Biomaterials in conjunction with the Thirteenth Annual International Biomaterials Symposium, Troy, NY, May 28-31, 1981. (1983)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 17 (1983), S. 411-425 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The controlled failure of polypropylene (PP) sutures is studied via creep rupture tests. From plots of log time (tB) vs. stress (σ), linear relationships are generated over the failure times of 1-1000 h. Results show that as a function of stress, the time dependence varies with irradiation dose (15, 20, 25, and 50 Mrad), irradiation atmosphere (air and vacuum), suture diameter (7-0, 6-0, 5-0, and 4-0), and test temperature (26 and 37°C). For a given stress, the time to failure is least for the greatest dose in the presence of air and at the highest temperature. When suture loops are wrapped around a small wire sheave, however, failure occurs in the largest suture as much as two decades sooner than the smallest suture studied. Within the limitations stated herein, they are independent of test method, loop diameter, aging, and humidity. Consequently, after irradiation in vacuum and postirradiation heat treatment, the processed material may be stored at room temperature for at least 1 month. Such materials are advocated when the time release of a dental or medical device is required, for example, in the self-activating cleft palate appliance.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820170303
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic mechanical properties of amalgamsPresented, in part, at the I.A.D.R. Meeting, New Orleans, March, 1979 (Abstract #29). (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 47-59 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A recently developed dynamic mechanical analysis technique was utilized to determine the setting rates of dental amalgams. Via a compound parallel beam apparatus the dynamic mechanical properties of five amalgam materials were continuously measured at 37°C within ca. 7 min after the start of trituration. Over a 15 hr period results showed that the modulus of elasticity (Ea) increased from 1.2 × 1010 Pa to 6.5 × 1010 Pa - the latter generally approaching those values reported via ultrasonic techniques. Moduli results via compression tests on microspecimens (3 × 2 × 1 mm) paralleled previous reliable literature data, nominally yielding values for Ea of 2-3 × 1010 Pa. The extent of Ea scatter from both inter- and intrapreparer experiments appeared similar, although superior technique generally could be recognized by a systematic shift of the mean results to higher Ea's. In addition to modulus studies both compressive strengths (σmax) and their corresponding strains (∊) were measured on microspecimens at a strain rate (∊) of 0.031 min-1, with a significant increase being noted in σmax for the one material tested at over an order of magnitude increase in ∊.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150109
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  • 7
    Electronic Resource
    Electronic Resource
    Age-hardening and tensile properties of low gold (10-14 kt.) alloys (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 117-135 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The age-hardening and tensile properties were determined for seven 10-14 kt. gold alloys, a conventional type II, and a sterling silver alloy. For the low-gold alloys the heat hardening curves indicated that the maximum aging effects were attained after 30 min at 400°C. From tensile tests on either wire or dumbbell specimen configurations, Young's modulus (E), proportional limit (P.L.), ultimate tensile strength (U.T.S.), and elongation to break were measured for alloys in both the solution annealed (S) and the hardened (H) state. These stress-strain data not only confirmed previous correlations noted for conventional gold alloys between either E, P.L., or U.T.S. and hardness and between U.T.S. and P.L., but also varied systematically with the Au/Cu ratios in the (H) state. Under identical heat treatment and tensile testing conditions, comparison of the manufacturers' cast samples with this laboratory's specimens showed that, while the E, P.L., and U.T.S. differed somewhat, the greatest change occurred in the elongation to break. Here after measuring the porosity of the different specimen configurations and analyzing the log10 elongation with VHN, the conclusion was clear: Specimen geometry markedly influenced the physical properties. On this basis the proposed dumbbell geometry is advocated over the wire specimen configuration currently cited in ADA Specification No. 5.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150202
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of the suture diameter on the tensile strength of polypropylene monofilaments and its relationship to the USP specificationPresented, in part, at the Second World Congress on Biomaterials, Washington, D.C., April, 1984. (1984)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 18 (1984), S. 781-787 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Ethylene gas sterilized polypropylene monofilaments were tested in a straight pull as well as in a conventional knot pull tensile test. In either case an analysis of the results indicates that the occurrence of “surface steps” may explain the relationship between strength and suture diameter. The present investigation not only shows that the polypropylene specification could be established on a more fundamental basis (using 60% of the ultimate tensile strength as the generalized criterion) but also suggests that other sutures should be evaluated similarly.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820180708
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