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Moisture is a known issue for carbon fiber reinforced polymer (CFRP) manufacturing. During the process, in which a CFRP prepreg is carefully thawed, cut, stacked, and cured into a laminate, any bad moisture control can cause voids, affect the curing, and degrade the laminate. Recent studies of carbon nanofiber z-threaded CFRP (i.e., ZT-CFRP) prepreg and its laminates showed significant multifunctional improvements in the mechanical strengths, toughness, thermal conductivity, and electrical conductivity. The carbon nanofibers zig-zag thread among the carbon fibers in the through-thickness direction (i.e., z-direction) and mechanically interlock the fiber system together to form an effective 3D-fiber-network reinforced laminate. This paper presents a preliminary experimental study on the ZT-CFRP prepreg when facing the moisture exposure during the prepreg handling and lamination process. Both the ZT-CFRP and traditional CFRP prepregs, subjected to different humidity conditions, will be cut, and cured into laminate samples. The samples will be tested for their interlaminar shear strengths (ILSS) and hardness. Microscope pictures of the samples' fracture patterns will be compared for explaining the combined impact of the moistures and the carbon nanofiber z-threading strategy on the laminates' interlaminar shear strength and curing state.
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Nanofiber z-threaded CFRP and the multifunctionality for advanced air mobility
Carbon fiber reinforced polymer (CFRP) is one of promising lightweight materials for advanced air mobility (and electrical vehicles) due to the high strength, low density, and corrosion resistance. On the other hand, CFRP is more expensive than many lightweight alloys, difficult to join, less fire-resistant, lower conductivities in thermal and electrical energy, more sensitive in processing defects, and more difficult to inspect its structural damages. To improve the multifunctionality desired by advanced air mobility, CFRP could be modified with nanoparticles. Nanofiber z-threaded CFRP (ZT-CFRP) technology utilizes millions of long carbon nanofibers to z-directionally thread through all carbon fibers in per square-centimeters of ZT-CFRP prepreg. The ZT-CFRP enhanced the mechanical properties, thermal conductivity, and electrical conductivity. The unique 3D-multicscaled fiber-reinforced microstructure also provide additional performance such as enhanced resistance against the property degradation caused by void, enhanced flame-retardance, improved adhesive-joint (i.e., bond line) strength, and enhanced thermal infrared damage/defect evaluation resolutions. This paper will overview the ZT-CFRP performances along with the state of ZT-CFRP prepreg process development including the scaled up roll-to-roll hot-melt manufacturing process of the ZT-CFRP prepreg. Its potentially useful multifunctional attributes for advanced air mobility will also be discussed in this paper.
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- Award ID(s):
- 2044513
- PAR ID:
- 10564854
- Publisher / Repository:
- Society of Plastics Engineers (SPE®) International www.4spe.org
- Date Published:
- Format(s):
- Medium: X
- Location:
- Novi, MI
- Sponsoring Org:
- National Science Foundation
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Carbon fiber reinforced polymer (CFRP) composites have been increasingly used in many vehicles such as airplanes, automobiles, and ships due to the advantages of high-strength, high-modulus, lightweight, and corrosion resistance. CFRP structures enhance the vehicle's performance, energy-efficiency, comfort, and safety. However, a common safety concern is how the CFRP materials perform when the vehicle is in fire and if there are enough time to safely evacuate the passengers. The elevated temperature can soften and decompose the polymer matrix, delaminate the CFRP laminate, and burn the CFRP through the contact with oxygen. As a result, the thermal and flammability response of CFRP is important for considering CFRP for vehicle applications; and some specialty high-temperature or flame/smoke/toxicity-proven resins have been investigated for CFRP parts manufacturing due to the needs. In this paper, a novel flame resistant hypothesis of utilizing the unique nano/micro- interlocked fiber reinforcing structure of the long-range carbon nanofiber z-threaded CFRP (ZT-CFRP) composite laminates for improving the flammability performance will be investigated. The carbon nanofibers (CNT) and carbon nanotubes (CNT), which have excellent thermal and mechanical properties, will be dispersed in an epoxy resin and will zig-zag thread through a carbon fiber fabric using an electrical/flow assisted impregnation process to create the unidirectional ZT-CFRP prepregs, respectively, which will be further processed into ZT-CFRP composite laminates. The UL-94 flammability test will be employed to characterize the ZT-CFRP laminates' flammability performance against the control baseline data of the regular CFRP, all without using any flame retardant chemicals. An impressive self-extinguishing flammability characteristic of the CNF based ZT-CFRP samples has been distinctly identified from all the samples. The UL-94 testing results and the effectiveness of using the long-range nanofiber z-threading strategy for enabling the novel nano/microstructure-induced flame resistant and self-extinguishing characteristics will be discussed.more » « less
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