Improvement of Impact Energy of Cellulose Nanofiber-added CFRP by Water Absorption under High Temperature and Pressure Conditions
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors​ :
Seiji MITSUBAYASHI (JAPAN), Kenichi TAKEMURA (JAPAN)Abstract :
Carbon fiber reinforced plastics (CFRP) are used in a wide range of fields such as automotive and aerospace industries due to their high specific strength. Since CFRP used in these fields requires high impact resistance, studies have been conducted on water absorption of CFRP to improve its impact resistance. Hironaka et al. reported that long-term water absorption of CFRP improved the impact value by up to 8% compared to the value before water absorption. Therefore, it is expected that the impact resistance of CFRP can be improved by increasing its water absorption. Therefore, in this study, we focused on water absorption under high temperature and pressure conditions.
Recently, cellulose nanofibers (CNFs) derived from plants have attracted attention as a material to improve the mechanical properties of CFRP. Hayashi et al. reported that the addition of CNF to CFRP improved the flexural properties and interfacial bond strength. Nomura et al. also showed that the addition of CNF improved the vibration damping properties of CFRP. Therefore, the addition of CNF is expected to improve the impact strength of CFRP. However, the effect of water absorption under high temperature and pressure conditions on the impact properties of CNF-added CFRP has not been clarified. Therefore, the objective of this study was to clarify the effect of water absorption under high temperature and pressure conditions on the impact energy of CNF-added CFRP.
In this study, the water absorption rate was measured by adjusting the pressure, CNF addition rate, and water absorption time, and the changes in water absorption were compared. Izod impact tests were also conducted to evaluate the effect of water absorption under high temperature and pressure conditions on the impact properties of CNF-added CFRP.
The results showed that the water absorption rate of CFRP without CNF and CFRP with CNF tended to increase with the water absorption time and then saturated at a certain value. The water absorption rate and impact energy tended to increase as the pressure during water absorption increased, and as the CNF addition rate increased, the water absorption and impact energy increased compared to the condition without CNF. It is suggested that in contrast to hydrophobic CFRP, water absorption in CFRP may be enhanced by the addition of hydrophilic CNF.
The following conclusions are obtained from this study. The results indicate that the addition of CNF to CFRP, under high-temperature and high-pressure conditions, improves impact energy compared to CFRP without CNF. Furthermore, it was suggested that the improvement in the impact characteristics of water-absorbed CFRP due to the addition of CNF can be attributed to the hydrophilic property of CNF.
Recently, cellulose nanofibers (CNFs) derived from plants have attracted attention as a material to improve the mechanical properties of CFRP. Hayashi et al. reported that the addition of CNF to CFRP improved the flexural properties and interfacial bond strength. Nomura et al. also showed that the addition of CNF improved the vibration damping properties of CFRP. Therefore, the addition of CNF is expected to improve the impact strength of CFRP. However, the effect of water absorption under high temperature and pressure conditions on the impact properties of CNF-added CFRP has not been clarified. Therefore, the objective of this study was to clarify the effect of water absorption under high temperature and pressure conditions on the impact energy of CNF-added CFRP.
In this study, the water absorption rate was measured by adjusting the pressure, CNF addition rate, and water absorption time, and the changes in water absorption were compared. Izod impact tests were also conducted to evaluate the effect of water absorption under high temperature and pressure conditions on the impact properties of CNF-added CFRP.
The results showed that the water absorption rate of CFRP without CNF and CFRP with CNF tended to increase with the water absorption time and then saturated at a certain value. The water absorption rate and impact energy tended to increase as the pressure during water absorption increased, and as the CNF addition rate increased, the water absorption and impact energy increased compared to the condition without CNF. It is suggested that in contrast to hydrophobic CFRP, water absorption in CFRP may be enhanced by the addition of hydrophilic CNF.
The following conclusions are obtained from this study. The results indicate that the addition of CNF to CFRP, under high-temperature and high-pressure conditions, improves impact energy compared to CFRP without CNF. Furthermore, it was suggested that the improvement in the impact characteristics of water-absorbed CFRP due to the addition of CNF can be attributed to the hydrophilic property of CNF.