Enhanced durability of carbon nanotube grafted hierarchical ceramic microfiber-reinforced epoxy composites

Abstract

As carbon nanotube (CNT) infused hybrid composites are increasingly identified as next-generation aerospace materials, it is vital to evaluate their long-term structural performance under aging environments. In this work, the durability of hierarchical, aligned CNT grafted aluminoborosilicate microfiber-epoxy composites (CNT composites) are compared against baseline aluminoborosilicate composites (baseline composites), before and after immersion in water at 25 °C (hydro) and 60 °C (hydrothermal), for extended durations (90 d and 180 d). The addition of CNTs is found to reduce water diffusivities by approximately 1.5 times. The mechanical properties (bending strength and modulus) and the damage sensing capabilities (DC conductivity) of CNT composites remain intact regardless of exposure conditions. The baseline composites show significant loss of strength (44 %) after only 15 d of hydrothermal aging. This loss of mechanical strength is attributed to fiber-polymer interfacial debonding caused by accumulation of water at high temperatures. In situ acoustic and DC electrical measurements of hydrothermally aged CNT composites identify extensive stress-relieving micro-cracking and crack deflections that are absent in the aged baseline composites. These observations are supported by SEM images of the failed composite cross-sections that highlight secondary matrix toughening mechanisms in the form of CNT pullouts and fractures which enhance the service life of composites and maintain their properties under accelerated aging environments.

Enhancing the thermal and electrical conductivities of silicone rubber composites by constructing a 1D‐3D collaborative network

“…As a reinforcing material, CNTs possess excellent mechanical properties, [51] and the hollow-cage-like structure of CNTs can absorb a certain amount of stress and hinder the propagation of cracks. [53][54][55][56] In the abnormal modulus of CCR-4 can be explained by the combined effect of CNTs lubricity and agglomeration. [57,58] Lubrication effect of CNT helps the movement of rubber molecular chain and increases the flexibility of composites.…”

Interface engineering of carbon fiber composites using CNT: A review

“…Several works investigate growing CNTs onto the fibers, be it metal fibers like aluminium 43–45 or ceramic, 46 carbon 47 or glass fibers 48 . Some work also studied growing nanofiber on carbon fibers 44,49 .…”

“…The reduction of effective elastic moduli up to 100 times has been observed due to CNT waviness. 42 Several works investigate growing CNTs onto the fibers, be it metal fibers like aluminium [43][44][45] or ceramic, 46 carbon 47 or glass fibers. 48 Some work also studied growing nanofiber on carbon fibers.…”

Triboluminescent composite microspheres consisting of alginate and EuD4TEA crystals

“…Damage sensing in situ attracts increasing attention in various fields such as material fracture [1,2,3], earthquake prediction and monitoring [4], and mechanobiology [5,6,7]. The sensor elements usually are powdery piezo/tribo luminescent materials placed on a substrate [8].The key point is the development of a suitable substrate material that allows obtaining a homogeneous distribution of the luminescent materials and maintaining the maximum transmittance of the optical signal created upon mechanical action.…”