(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: To measure the mechanical properties of the synthetic polymer, Polyvinyl-alcohol cryogel (PVA-c) for previously unexamined sample geometries which are more representative of the geometries of PVA-c based vessel phantoms. This is relevant for flow phantom experiments as the mechanical properties of PVA-c depend on a number of factors, including sample volume and rate of thaw when undergoing freeze thaw cycles. Therefore correlation between test samples and vessel mimicking material samples may not be guaranteed.
Methods: A series of cylindrical PVA-c samples were produced for mechanical testing under identical production conditions to vessel mimicking material. From the same batch of PVA-c a series of “dumbbell� test objects were produced following the specifications of ISO 37. The samples underwent a range of freeze-thaw cycles (2 – 4) in order to modify the Young’s modulus of the PVAc material, producing four “levels� of stiffness. Using the procedure laid out in ISO 37, these samples were mechanically characterised using a Lloyd Instruments LR30KPlus tensile testing system (Ametek, USA). The resulting stress-strain curves were analysed in MATLAB (Mathworks, USA).
Results: It was found that the Young’s modulus values of the cylindrical samples were highly correlated with those of the dumbbell samples (R² = 0.9767) and there was no significant difference in sample stiffness detectable between each sample type using a paired t-test (p = 0.8821).
Conclusion: From these results, it is clear that the dumbbell sample geometry outline in ISO 37 can be taken to be representative of the mechanical properties exhibited by the vessel geometries used in flow experiments where vessel stiffness is important, and provides a direct comparison in Young’s modulus values provided the samples are made under identical production conditions.
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