ISSN:
0021-9304
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Medizin
,
Technik allgemein
Notizen:
Four self-curing acrylic bone cements were surveyed by infrared, solubility, viscometry, quantitative metallography, microscopy, and physical testing techniques: CMW, Palacos R, Sulfix-6, and Surgical Simplex P. Results show that these bone cements were primarily composed of poly(methyl methacrylate) and that no cross-linking was evident. Solubility analysis confirmed this latter observation, as the bone cements dissolved completely except for a small insoluble fraction, which was identified as the radiopaque filler. For each bone cement, the viscosity-average molecular weights of both the powdered phase and the cured two-phase product remained unchanged, varying overall from 1 to 5 × 105. Using standard quantitative metallography, porosity ranged from 1 to 8% and the dispersed powder phase decreased 11-46%. Microscopy revealed the nature of the porosity, radiopaque fillers, the powder size and shape, and the fracture morphology. From tensile and fracture toughness tests, five physical properties were determined at ambient conditions and at 37°C after conditioning in distilled water at 37°C for 10 months: the modulus of elasticity, the ultimate tensile strength, the elongation at break, the fracture energy, and the mean inherent flaw size. At ambient conditions, the ultimate tensile strength decreased 33-55% when compared with commercial unmodified poly(methyl methacrylate), Plexiglas G. While the fracture energy remained rather invariant, the mean inherent flaw size increased fivefold over the commercial acrylic tested. This marked increase in the mean inherent flaw size could lower the fatigue resistance of a material, since more and/or larger fracture initiation sites are available. When tested at 37°C after protracted conditioning, the deleterious trends observed at ambient temperature continued. To some degree, porosity, particle-matrix interfaces, residual stresses, low molecular weight products, inorganic and/or other organic additions, and water contributed to the inherent flaw size at the expense of the working stress. Several modifications are suggested by which the importance of these factors might be minimized.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jbm.820120304
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