An Experimental Investigation of the Mechanism of Hygrothermal Aging and Low-Velocity Impact Performance of Resin Matrix Composites

• Published in: Polymers Vol. 16; no. 11; p. 1477
• Main Authors: Zhang, Yuxuan, Yan, Shi, Wang, Xin, Guan, Yue, Du, Changmei, Fan, Tiancong, Li, Hanhua, Zhai, Junjun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 23.05.2024; MDPI
• Subjects: Aging; Analysis; Braided composites; Carbon fibers; Chemical processes; Composite materials; Epoxy resins; Fourier transform infrared spectroscopy (FT-IR); Fourier transforms; Humidity; hygrothermal aging; low-velocity impact (LVI); Mechanical properties; Methods; Microchannels; Moisture; Moisture absorption; Oxygen content; Relative humidity; Resin matrix composites; Shear strength; Spectrum analysis; Steel pipes; Substrates; Temperature; thermogravimetric analysis (TGA); Three dimensional composites; three-dimensional braided composites; Water; Water absorption; Water chemistry; China; resin matrix composites; C-scan; low-velocity impact (LVI); Fourier transform infrared spectroscopy (FT-IR); SEM; thermogravimetric analysis (TGA); three-dimensional braided composites; hygrothermal aging
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym16111477

Resin matrix composites (RCs) have better thermal and chemical stability, so they are widely used in engineering fields. In this study, the aging process and mechanism of two different types of resin-based three-dimensional four-way braided composites (H15 and S15) under different hygrothermal aging conditions were studied. The effect of aging behavior on the mechanical properties of RCs was also studied. Three different aging conditions were studied: Case I, 40 °C Soak; Case II, 70 °C Soak; and Case III, 70 °C-85% relative humidity (RH). It was found that the hygroscopic behavior of RCs in the process of moisture-heat aging conforms to Fick's second law. Higher temperatures and humidity lead to higher water absorption. The equilibrium hygroscopic content of H15 was 1.46% (Case II), and that of S15 was 2.51% (Case II). FT-IR revealed the different hygroscopic mechanisms of H15 and S15 in terms of aging behavior. On the whole, the infiltration behavior of water molecules is mainly exhibited in the process of wet and thermal aging. At the same time, the effect of the aging process on resin matrices was observed using SEM. It was found that the aging process led to the formation of microchannels on the substrate surface of S15, and the formation of these channels was the main reason for the better moisture absorption and lower mechanical strength of S15. At the same time, this study further found that temperature and oxygen content are the core influences on post-aging strength. The LVI experiment also showed that the structural changes and deterioration effects occurring after aging reduced the strength of the studied material.