Georg Bechtold
Institut fur Verbundwerkstoffe GmbH
University of Kaiserslautern
Kaiserslautern, Germany
Date: Tuesday, February 17, 1998
Time: 3:30 p.m.
Place: W128 Nebraska Hall
Fibre-Reinforced Thermoplastic Composite Osteosynthesis Implants With Variable Mechanical Properties For Better Treatment of Bone Fractures
A new thermoplastic composite femoral implant was designed and manufactured following the concept of semi-rigid fixation. By integrating a biodegradable polymer block into the body of the implant it was made sufficiently rigid to initially enable primary bony union but, with progressive degradation, to also enable interfragmentary movement, which promotes the proliferation of external callus and consequently a better consolidation of the fracture. In order to meet medical standards the parts of the implant were manufactured by injection moulding and near-net-shape forming. The degradation behavior of Poly (L-lactide) was studied in-vitro under static and dynamic loading conditions. It was found that dynamic loading leads to mechanical degradation of the polymer long before hydrolytic degradation commences.
Fiber Reinforced Profiles Produced by Thermoplastic Pultrusion
Pultrusion is a continuous composite material production method. With common techniques, straight axial reinforced profiles with small constant cross sections are produced. hermoset pultrusion is a well developed manufacturing method currently in widespread use. However, it is to be expected that certain properties of thermoplastic matrices offer considerable advantages compared to thermoset matrices, e.g. higher ductility, better chemical resistance and recyclability. The main problems in thermoplastic pultrusion are the high processing temperatures, high melt viscosities and a lack of both fundamental understanding of the governing process mechanisms and adequate mathematical models for predicting the dependence of properties the various processing variables. One goal of this work is to contribute to this modeling and prediction effort. Further, until now, there has been little experience in adding an off-axis reinforcement to pultruded profiles. By integrating a braiding machine into the process, additional reinforcement directions can be obtained. A possible practical application of pultruded tubes is presented.
