Woven Kevlar Fiber/Polydimethylsiloxane/Reduced Graphene Oxide Composite-Based Personal Thermal Management with Freestanding Cu–Ni Core–Shell Nanowires

Abstract

Thermotherapy is a widespread technique that provides relief for muscle spasms and joint injuries. A great deal of energy is used to heat the surrounding environment, and heat emitted by the human body is wasted on our surroundings. Herein, a woven Kevlar fiber (WKF)-based personal thermal management device was fabricated by directly growing vertical copper–nickel (Cu–Ni) nanowires (NWs) on the WKF surface using a hydrothermal method. The treated WKF was combined with reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) to form composites using vacuum-assisted resin transfer molding (VARTM). This WKF-based personal thermal management system contained a conductive network of metallic NWs and rGO that promoted effective Joule heating and reflected back the infrared (IR) radiation emitted by the human body. It thus behaved as a type of thermal insulation. The Cu–Ni NWs were synthesized with a tunable Ni layer on Cu core NWs to enhance the oxidation resistance of the Cu NWs. The combined effect of the NW networks and rGO enabled a surface temperature of 70 °C to be attained on application of 1.5 V to the composites. The Cu3Ni1–WKF/PDMS provided 43% more thermal insulation and higher IR reflectance than bare WKF/PDMS. The absorbed impact energy and tensile strength was highest for the Cu1Ni3- and rGO-integrated WKF/PDMS samples. Those Cu–Ni NWs having higher Ni contents displayed better mechanical properties and those with higher Cu contents showed higher Joule heating performance and IR reflectivity at a given rGO loading. The composite shows sufficient breathability and very high durability. The high flexibility of the composites and their ability to generate sufficient heat during various human motions ensures their suitability for wearable applications.

Low‐Resistant Electrical and Robust Mechanical Contacts of Self‐Attachable Flexible Transparent Electrodes with Patternable Circuits

“…Flexible transparent heaters have attracted substantial attention owing to its high optical transparency and applicability to non‐planar surfaces for a wide range of emerging applications, including smart windows and personal thermal management. [ 5,37 ] This transparent flexible heater also should form conformal mechanical contacts with the target substrates while ensuring stable electrical connections with the metal contact pads used for the application of bias voltage. Although previous transparent flexible heaters based on embedded percolating nanowire networks demonstrated superior resistive heating performance even under high mechanical deformation, they did not exhibit self‐attachable capability.…”

“…Although previous transparent flexible heaters based on embedded percolating nanowire networks demonstrated superior resistive heating performance even under high mechanical deformation, they did not exhibit self‐attachable capability. [ 5,37 ] Accordingly, electrical connections using mechanical clippers or Ag paste were typically utilized without effectively considering the interfacing or contact formation technology. We examined the contact formation behavior and Joule‐heating performance of the AF‐TCE.…”

Printed Flexible Heaters‐Based Thermotherapy Platform for Multiduty Thermal Management

“…Nowadays, the novel materials, such as graphene, [ 6 ] metal nanowires (NWs), [ 7 ] and their hybrid materials, [ 8 ] are often developed to fabricate the FHs. Comparatively, the metal NWs with high aspect ratios can decrease the junction resistances of neighbored NWs, making them more suitable for manufacturing high‐performance FHs.…”

Composite Materials Based on Henequen Fiber as a Thermal Barrier in the Automotive Sector

“…Values of Young's modulus and tensile strength have been reported between 9.4 and 22 GPa and between 468 and 640 MPa, respectively, for this henequen fiber [46]. e thermomechanical properties of fiber-based composites (carbon, glass, or natural fiber) depend in large part on the properties of the polymer matrices used in their construction, the properties of the constituent additives added (metals, metal oxides, or others), and the interaction between the polymer matrix, the added constituents, and the fibers used [47][48][49].…”