title: Physical aging and the creep behavior of acrylic bone cements.
abstract: The creep deformation of two acrylic bone cements, Palacos R+G and SmartSet GHV, was investigated for different physical aging times ranging from 45 min to 2 (1/2) years. The experiments were carried out in a three-point-bending set-up in 37 degrees C Ringer's solution applying 10 MPa or 25 MPa creep loads. Both bone cements exhibit a significant decrease of their creep compliance with increasing physical aging time. The experimental data were analyzed with a creep law discussed in the context of physical aging by Struik, and a modified Burgers' model which can be used to separate the strain response of the bone cements into an elastic, a visco-elastic and a creep component. The creep behavior of the bone cements could be described essentially with only one parameter of Struik's creep law. The analysis with the modified Burgers' model showed that physical aging influences all model parameters which are directly related to the mobility of the polymer chains. The effect of physical aging should be taken into account particularly if the mechanical performance of bone cements shortly after curing is investigated.
authors.affiliation: Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
authors.forename: Oleksii
authors.initials: O
authors.lastname: Kuzmychov
authors.affiliation: Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Koplin
authors.affiliation: Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Jaeger
authors.affiliation: Heraeus Medical GmbH, Wehrheim, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Büchner
authors.affiliation: Heraeus Medical GmbH, Wehrheim, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Gopp
mesh_terms: D000465:Algorithms; D001843:Bone Cements / Q000737:chemistry*; D004548:Elasticity; D008422:Materials Testing; D015233:Models, Statistical; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D013997:Time Factors
chemical_list: D001843:Bone Cements