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Open AccessArticle

Tortuosity Index Based on Dynamic Mechanical Properties of Polyimide Foam for Aerospace Applications

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Department of Mechanical Engineering, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USA
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Department of Engineering Science and Materials, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USA
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Department of Civil Engineering, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USA
*
Author to whom correspondence should be addressed.
Materials 2019, 12(11), 1851; https://doi.org/10.3390/ma12111851
Received: 22 April 2019 / Revised: 4 June 2019 / Accepted: 5 June 2019 / Published: 7 June 2019
The determination of a reliable tortuosity index is lacking in the aerospace industry. Therefore, a methodology is formulated via direct and indirect characterization methods of a fluid-filled porous media. Chemical, thermal, and mechanical characterization was performed to the PolyuMACTM polyimide foam. Tortuosity was measured considering a pressure difference as the resistivity variable, rather than electrical resistivity or molecular diffusivity, as proposed on previous models. This is an empirical establishment of the tortuosity index considering the correlation among hydraulic and structural dimensionless parameters obtained through the Buckingham’s Pi theorem. The behavior of the polyimide was studied for samples of different lengths compressed at 30%, 60%, and 90% of its original length on the foaming direction. Results show that, porosity, sample length, and fluid viscosity are relevant for the insulation performance of the material. Regression analysis produced a significant statistical model fit to the data correlated from the dimensionless parameters for each dynamic compression series. View Full-Text
Keywords: tortuosity index; polyimide foam; PolyuMACTM; aerospace material tortuosity index; polyimide foam; PolyuMACTM; aerospace material
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Flores-Bonano, S.; Vargas-Martinez, J.; Suárez, O.M.; Silva-Araya, W. Tortuosity Index Based on Dynamic Mechanical Properties of Polyimide Foam for Aerospace Applications. Materials 2019, 12, 1851.

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