Tensile strength of cryo-thermal treated composites

The reliability of short fiber reinforced polymer composites in extreme cryo-thermal cycle servicing conditions is crucial for their successful applications in aerospace engineering but their mechanical behaviors are not clear yet under harsh environments with sharp temperature changes. This study investiagtes the influences of cryo-thermal cycling (CTC) from -196 ℃ to 170 ℃ (sharp temperature change) on the tensile properties of short carbon fiber (SCF)/polyetherimide (PEI) composites at room temperature (25 ℃) and elevated temperature (170 ℃). First, SCFs were sized with the hybrid sizing agent of polydomaine (PDA) and carbon nanotubes (CNTs), and then SCF reinforced PEI composites were prepared via the facile injection molding technique. Impressively and unexpectedly, the tensile strength at 25 ℃ and 170 ℃ of SCF/PEI composites is all enhanced by the CTC treatment. The results show that the enhancement in the tensile strength of SCF/PEI composites is attributed to both the improved strength of PEI matrix and the enhanced fiber/PEI interfacial adhesion property after the CTC treatment. In addition, CNT-PDA sizing and CTC treatment have a combined effect on improving the tensile properties of SCF/PEI composites at 25 ℃ and 170 ℃. Overall, the SCF/PEI composites exhibit excellent mechanical properties under extreme service conditions, and are thus promising to serve as aerospace components that need to undergo severe environments with sharp temperature changes.