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Investigating impacts of moisture and cryogenic conditioning on physical properties of thermoplastic and thermoset carbon fiber composites
Andrade, Emanuel
Andrade, Emanuel
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2025-12-01
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Fiber-reinforced thermoplastic composites (FRTC) are widely utilized in various engineering applications, including space, defense, transportation, and energy because of their high strength, durability, and lightweight properties. However, one of the primary challenges in using thermoplastic composites in aerospace is their mechanical and thermal performances at cryogenic conditions, less than -150 °C. One potential concern of FRTCs is moisture ingression, or the introduction of water into the material matrix, that may increase the level of microcrack formation at cryogenic conditions and reduce the overall mechanical properties. To address these moisture concerns, this study investigated the mechanical properties of FRTCs (TORAYCA® 1100) Fiber)/low-melting polyaryletherketone (LM PAEK)) before and after moisture ingression under cryogenic conditions. Moisture ingression was initially induced by continuous soaking in DI water. Initial samples without any cryogenic conditioning were soaked for 3 weeks and demonstrated gains ranging from 0-0.5 wt.%. Further soaking of samples saw upwards of 1 wt.% growth over 13 weeks before cryogenic conditioning via repeated insertion into liquid nitrogen. In this effort, two thermoset composite prepregs (TORAYCA® 3960) with reported weights of 192 and 70 gsm and a thermoplastic (TORAYCA® Cetex TC1225) with quasi-isotropic layups of [45/0/-45/90]s or [45/0/-45/90]2s were investigated using FTIR, DSC, TGA, and 3-point bending. Results demonstrated that despite slow moisture intake, the 192 gsm specimen demonstrated significant degradation mechanically, showing flexural strength drops as high as -46.36% between wet and dry specimens while the 70 gsm and LM PAEK thermoplastic specimens were negligibly impacted when comparing the cryogenic results, indicating further testing is needed to determine the limits of these specimens cryogenically
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Thesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Wichita State University
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© Copyright 2025 by Emanuel Andrade
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