4 research outputs found
Heat-Shielding Nanobrick Wall for Carbon Fiber-Reinforced Polymer Composites
Owing to their excellent mechanical
properties, carbon
fiber-reinforced
polymer (CFRP) composites have a broad spectrum of applications in
aerospace, civil engineering, automotive, and numerous industrial
fields. Despite their many advantages, the inherent lack of thermal
stability of the polymer matrix results in the loss of the composite’s
mechanical properties when exposed to elevated temperatures. In an
effort to provide thermal protection, a multilayer film composed of
tris(hydroxymethyl)-aminomethane (THAM)-buffered polyethylenimine
(PEI) and vermiculite (VMT) clay was deposited on CFRP composites
via layer-by-layer assembly. When subjected to the flame from a butane
torch and mechanical loading, the polymer–clay nanobrick wall
provides substantial thermal insulation, decreasing the temperature
on the backside of the CFRP composites by as much as 100 °C.
The PEI-THAM/VMT coating also helps to maintain the storage modulus
of the composite and offers significant protection from oxidative
degradation, as confirmed by dynamic mechanical analysis and X-ray
photoelectron spectroscopy. The performance of this polymer–clay
multilayer film provides excellent thermal barrier that can be used
to protect advanced composite materials from extreme heat
One-Step Synthesis of Antioxidative Graphene-Wrapped Copper Nanoparticles on Flexible Substrates for Electronic and Electrocatalytic Applications
In
this study, we report a novel, one-step synthesis method to fabricate
multilayer graphene (MLG)-wrapped copper nanoparticles (CuNPs) directly
on various substrates (e.g., polyimide film (PI), carbon cloth (CC),
or Si wafer (Si)). The electrical resistivities of the pristine MLG-CuNPs/PI
and MLG-CuNPs/Si were measured 1.7 × 10<sup>–6</sup> and
1.4 × 10<sup>–6</sup> Ω·m, respectively, of
which both values are ∼100-fold lower than earlier reports.
The MLG shell could remarkably prevent the Cu nanocore from serious
damages after MLG-CuNPs being exposed to various harsh conditions.
Both MLG-CuNPs/PI and MLG-CuNPs/Si retained almost their conductivities
after ambient annealing at 150 °C. Furthermore, the flexible
MLG-CuNPs/PI exhibits excellent mechanical durability after 1000 bending
cycles. We also demonstrate that the MLG-CuNPs/PI can be used as promising
source-drain electrodes in fabricating flexible graphene-based field-effect
transistor (G-FET) devices. Finally, the MLG-CuNPs/CC was shown to
possess high performance and durability toward hydrogen evolution
reaction (HER)
Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength
Current thermally conductive and electrically insulating
insulation
systems are struggling to meet the needs of modern electronics due
to increasing heat generation and power densities. Little research
has focused on creating insulation systems that excel at both dissipating
heat and withstanding high voltages (i.e., have both high thermal
conductivity and a high breakdown strength). Herein, a polyelectrolyte-based
multilayer nanocomposite is demonstrated to be a thermally conductive
high-voltage insulation. Through inclusion of both boehmite and vermiculite
clay, the breakdown strength of the nanocomposite was increased by
≈115%. It was also found that this unique nanocomposite has
an increase in its breakdown strength, modulus, and hydrophobicity
when exposed to elevated temperatures. This readily scalable insulation
exhibits a remarkable combination of breakdown strength (250 kV/mm)
and thermal conductivity (0.16 W m–1 K–1) for a polyelectrolyte-based nanocomposite. This dual clay insulation
is a step toward meeting the needs of the next generation of high-performance
insulation systems
Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength
Current thermally conductive and electrically insulating
insulation
systems are struggling to meet the needs of modern electronics due
to increasing heat generation and power densities. Little research
has focused on creating insulation systems that excel at both dissipating
heat and withstanding high voltages (i.e., have both high thermal
conductivity and a high breakdown strength). Herein, a polyelectrolyte-based
multilayer nanocomposite is demonstrated to be a thermally conductive
high-voltage insulation. Through inclusion of both boehmite and vermiculite
clay, the breakdown strength of the nanocomposite was increased by
≈115%. It was also found that this unique nanocomposite has
an increase in its breakdown strength, modulus, and hydrophobicity
when exposed to elevated temperatures. This readily scalable insulation
exhibits a remarkable combination of breakdown strength (250 kV/mm)
and thermal conductivity (0.16 W m–1 K–1) for a polyelectrolyte-based nanocomposite. This dual clay insulation
is a step toward meeting the needs of the next generation of high-performance
insulation systems