Physical aging and the creep behavior of acrylic bone cements.
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.
Kuzmychov
Oleksii
O
Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
Koplin
Christof
C
Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
Jaeger
Raimund
R
Biomedical Materials and Implants Group, Fraunhofer-Institute for Mechanics of Materials, Freiburg, Germany.
Büchner
Hubert
H
Heraeus Medical GmbH, Wehrheim, Germany.
Gopp
Udo
U
Heraeus Medical GmbH, Wehrheim, Germany.
D000465:Algorithms; D001843:Bone Cements / Q000737:chemistry*; D004548:Elasticity; D008422:Materials Testing; D015233:Models, Statistical; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D013997:Time Factors
D001843:Bone Cements