Abstract
Abstract The selection of appropriate test conditions is of critical importance in mechanical testing of biomaterials. In particular the definition of dynamic test conditions is requiring high efforts. In this work, a thermoplastic semicrystalline polymer was characterized regarding mechanical properties by dynamic mechanical analysis (DMA). Timetemperature- superposition (TTS) of dynamic mechanical data provides an efficient method for the experimental design of follow-up studies. Our focus was to provide test conditions for cyclic tests, which correspond to viscoelastic materials. The results show, that the test temperature for dynamic mechanical fatigue tests, as an indicator of mechanical modification for viscoelastic materials, should necessarily remain below the onset temperatures of storage modulus and loss modulus. Moreover, changes in material characteristics due to varying frequencies should be considered when constructing a master curve for the evaluation of test frequencies. Therefore, TTS is particularly beneficial for the rapid determination of test parameters for accelerated material examination.
Highlights
In biomedical engineering, new applications and requirements have led to a focus on polymers over the last decade
In order to use the data of dynamic mechanical analysis (DMA) for the definition of test parameters for fatigue tests, especially wide frequency ranges and wide temperature ranges have to be investigated
6 samples of a representative, biodegradable biomaterial were investigated by DMA
Summary
New applications and requirements have led to a focus on polymers over the last decade. Multifrequency temperature sweeps include frequency sweeps at constant temperatures, as well as an incremental heating over time The determination of these relationships can be evaluated in a simplified way by the TTS and test parameters can be estimated. According to theory, this principle uses the equivalence of time and temperature to reduce test times and cover an extended frequency range. This principle uses the equivalence of time and temperature to reduce test times and cover an extended frequency range This has been shown for thermo-rheological simple polymers, especially single-phase, single transition and amorphous polymers with linear viscoelastic properties [1]. The resulting master curve was constructed by shifting these curves horizontally and vertically
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