Radio Frequency Heating of Carbon Nanotube Composite Materials

Abstract

Here, we give the first-ever report of radio frequency (RF) electromagnetic heating of polymer nanocomposite materials via direct-contact and capacitively coupled electric field applicators. Notably, RF heating allows nanocomposite materials to be resistively heated with electric fields. We highlight our novel RF heating technique for multiwalled carbon nanotube (MWCNT) thermoplastic composites and measure their broadband dielectric properties. We also demonstrate three different electric field applicator configurations and discuss their practical use in an industrial setting. We demonstrate the use of RF heating to cure an automotive-grade epoxy loaded with MWCNTs. Our results show that lap shear joints cured faster with the RF method compared with control samples cured in an oven because of the heat-transfer advantages of directly heating the epoxy composite. Finally, we implement our RF curing technique to assemble an automotive structure by locally curing an epoxy adhesive applied to a truck chassis.

Heating of Ti3C2Tx MXene/polymer composites in response to Radio Frequency fields

“…We utilize a frequency sweep to determine the resonant frequency has the highest resistive losses, and thus, the highest heating rate. The resonant frequency is the frequency at which the impedance of the source (RF generator) is closely matched to that of the sample, capacitor, and the connecting cables, leading to an efficient power transfer between the source and the sample 8 . The frequency sweep was programmed such that the sample was exposed to 3 W RF fields for 2 seconds (power turned on) followed by 12 seconds of cooling time (power turned off) at each frequency from 1–150 MHz (raw data shown in Fig.…”

“…One of the compelling properties of Ti 3 C 2 T x MXene is their high electrical conductivity, with reported values reaching 2.4 × 10 5 S m −1 , similar to that reported for multi-layered graphene 7 . Based on our recent reports showing that carbon nanomaterials rapidly heat in response to RF fields, we hypothesized that Ti 3 C 2 T x MXenes nanosheets would respond to RF fields as well 8 .…”

“…Our group has recently reported that nanomaterials show extraordinary heating rates in response to RF fields; Sweeney et al . 8 demonstrated rapid RF heating of multiwalled carbon nanotubes embedded in epoxy resin for curing industrial grade thermoset adhesives, for which RF-curing rate was localized, volumetric, and faster than conventional oven curing 8 .…”

Radio Frequency Driven Heating of Catalytic Reactors for Portable Green Chemistry

“…RF electric fields (1–200 MHz) can achieve faster and uniform heating compared to conventional methods, and they have a greater penetration depth than microwaves. [ 18 ] They have been studied for a variety of application ranging from medical ablation, [ 19 ] polymer welding, [ 20 ] wood drying, [ 21 ] and food processing applications. [ 22 ] Ioffe et al used high power RF (2.5 KW) for acetylene production from methane over activated carbon catalyst.…”

“…[ 23 ] In our recent work, carbon nanotubes and silicon carbide fibers were used as RF susceptors to cure preceramic polymers to silicon carbides for noncontact processing in 3D printing, composite manufacturing, and fiber processing. [ 18 ] Our group has studied RF susceptive nanomaterials including multi walled carbon nanotube (MWCNT), [ 20 ] metallic and semiconducting single walled carbon nanotube, [ 24 ] MXenes, [ 25 ] and silicon carbide fibers; [ 26 ] and these materials heat up to significantly high temperatures under low‐power RF radiation. The presence of sp 2 carbon in MWCNT and surface of SiC fibers results in rapid RF heating response.…”