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Impact Performance of a Hybrid ZnO Nanorod/Carbon Nanotube/Carbon Fiber Reinforced Polymer Composite



Carbon fiber reinforced polymer composites (CFRPs) are replacing traditional structural materials, due to their outstanding in-plane strength and stiffness. However, their out-of-plane and interlaminar performances are inadequate. Incorporating nanosized reinforcement into the CFRP structures was shown to potentially eradicate these vulnerabilities. Zinc oxide (ZnO) nanorods and carbon nanotubes (CNTs) are among possible nano reinforcement additives. In this study, a low temperature hydrothermal synthesis technique is utilized to grow ZnO nanorods on the surface of woven carbon fiber fabrics. A relatively low temperature CNT synthesis technique; graphitic structures by design (GSD), is also employed for grafting multi-walled carbon nanotubes (MWCNTs) on the surface of carbon fibers and on the ZnO nanorods to form hierarchical reinforcements. These two synthesis techniques provoke different surface treatment on the carbon fibers including the exposure to elevated temperatures, amorphous ZnO coating, water-soaking, ZnO nanorods growth and CNTs growth. Carbon fiber fabrics based on these different surface treatments were utilized to fabricate composite laminates. The quality of the synthesized nano reinforcements was studied via scanning electron microscopy (SEM). The energy absorption capabilities of the different hybrid composites were examined via out-of-plane high velocity (~90m/s) impact tests utilizing a spherical impactor. In order to study the progressive damage mechanism of the hybrid CFRPs, spherical punch tests were also carried out utilizing a punch identical in size to the high speed impactor projectile. Delamination damage of the hybrid CFRPs was also investigated using SEM micrographs of the samples’ damage region after impact tests. A 21% improvement in the impact absorption energy of the CFRPs comprising surface grown ZnO nanorods and MWCNTs was achieved, compared to the composite laminates based on the raw carbon fibers with no surface treatments.

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