Kinetics of carbon nanotube-loaded epoxy curing: Rheometry, differential scanning calorimetry, and radio frequency heating

Tezel, Guler Bengusu; Sarmah, Anubhav; Desai, Suchi; Vashisth, Aniruddh; Green, Micah J.

doi:10.1016/j.carbon.2020.12.090

Cited by 24 publications

(28 citation statements)

References 35 publications

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“…When exposed to alternating RF fields, polarized molecules and charged ions in the film will begin to rotate or collide in order to align with the field, leading to frictional losses as heat . This heating is typically rapid and highly localized, making RF heating useful for a number of applications including welding, heating food, and curing. − However, materials with low conductivity do not undergo RF heating because there is no electrical percolating network . On the other hand, materials with high conductivity tend to reflect the RF fields, resulting in no heating. , In this manner, the RF heating response may be considered as a proxy for the electrical properties of the (PDADMA/MXene) 10 multilayers.…”

Section: Results and Discussionmentioning

confidence: 99%

Electronic and Optical Property Control of Polycation/MXene Layer-by-Layer Assemblies with Chemically Diverse MXenes

Echols

Yun

et al. 2021

Langmuir

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MXenes, 2D nanomaterials derived from ceramic MAX phases, have drawn considerable interest in a wide variety of fields including energy storage, catalysis, and sensing. There are many possible MXene compositions due to the chemical and structural diversity of parent MAX phases, which can bear different possible metal atoms “M”, number of layers, and carbon or nitrogen “X” constituents. Despite the potential variety in MXene types, the bulk of MXene research focuses upon the first MXene discovered, Ti3C2T. With the recent discovery of polymer/MXene multilayer assemblies as thin films and coatings, there is a need to broaden the accessible types of multilayers by including MXenes other than Ti3C2T z ; however, it is not clear how altering the MXene type influences the resulting multilayer growth and properties. Here, we report on the first use of MXenes other than Ti3C2T z , specifically Ti2CT z and Nb2CT z , for the layer-by-layer (LbL) assembly of polycation/MXene multilayers. By comparing these MXenes, we evaluate both how changing M (Ti vs Nb) and “n” (Ti3C2T zvs Ti2CT z ) affect the growth and properties of the resulting multilayer. Specifically, the aqueous LbL assembly of each MXene with poly(diallyldimethylammonium) into films and coatings is examined. Further, we compare the oxidative stability, optoelectronic properties (refractive index, absorption coefficient, optical conductivity, and direct and indirect optical band gaps), and the radio frequency heating response of each multilayer. We observe that MXene multilayers with higher “n” are more electrically conductive and oxidatively stable. We also demonstrate that Nb2CT z containing films have lower optical band gaps and refractive indices at the cost of lower electrical conductivities as compared to their Ti2CT z counterparts. Our work demonstrates that the properties of MXene/polycation multilayers are highly dependent on the choice of constituent MXene and that the MXene type can be altered to suit specific applications.

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Section: Results and Discussionmentioning

confidence: 99%

Electronic and Optical Property Control of Polycation/MXene Layer-by-Layer Assemblies with Chemically Diverse MXenes

Echols

Yun

et al. 2021

Langmuir

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“…This required exposure time would also apply to the residence time of a sample being moved through an RF field. We chose a temperature of 250 °C because the curing kinetics model [ 28 ] and experiments show that the resin cures completely within 1 min at this target temperature, thereby allowing us to maximize the print and cure speed.…”

Section: Resultsmentioning

confidence: 99%

“…The parameters in Equation () ( k , m , and n ), were determined in our prior using DSC experiments in the temperature range of 80–110 °C. [ 28 ] The data collected from these experiments were fitted to the modified Kamal–Sourour equation, and the activation energy was calculated to be ≈33 kJ mol −1 using the Arrhenius equation. [ 28 ] The calculated activation energy was used in the model to compute k as a function of local temperature.…”

Section: Methodsmentioning

confidence: 99%

Rapid Manufacturing via Selective Radio‐Frequency Heating and Curing of Thermosetting Resins

Sarmah¹,

Desai²,

Tezel

et al. 2022

Adv Eng Mater

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Thermosetting polymers are stable, high-performance materials that are crosslinked by heating and curing at a specified temperature. These materials are mechanically strong and highly resistant to thermal and chemical degradation, such that thermoset composites are a popular choice for applications ranging from battery frameworks to aerospace and automotive frames. [1] Current manufacturing processes for thermosetting epoxy resins include molding and curing of the matrix in a hightemperature oven, which is energy, labor, and time consuming, and sets limits on achievable part geometries and process times. [2,3] Existing methodologies to form epoxy composites include stacking one layer over the other to make 3D parts. [4] The ability to 3D print these multilayered structures would allow for the free-form fabrication of complex geometries, eliminating the additional cost of ovens and specific molds for each part. Additive manufacturing has been extensively used to 3D print thermoplastics [5][6][7] and metals. [8][9][10] A development of such an on-demand, rapid production technique could facilitate a distributed manufacturing economy for high-performance composites. [11] There has been limited research in the field of printing thermosets from a reservoir of resin. Selective curing of photocurable resins on the upper interface of liquid reservoirs using UV light has been reported previously to print 3D structures. [12,13] The materials used to make structures using this method are at least partially made of UV curable resins rather than conventional commercial thermosets. Apart from this, a handful of technologies have been developed for the additive manufacturing of thermosets. Extrusion-based printing of thermosets has been made possible by printing inside a thixotropic support bath, followed by extraction from the bath and curing in an oven. [14] Other studies have shown that direct ink writing coupled with UV-assisted curing can be used to 3D print light-sensitive resins. [15,16] Studies have also added viscosity-modifying agents to make the resin shearthinning. This allows the resin to be printed via direct ink writing such that it can retain its shape after being extruded, before being transferred to an oven for curing. [17][18][19] Additive manufacturing of thermosets via frontal polymerization has been explored to print complex shapes but is restricted by the limited number of resin chemistries that can be printed using this method. [20,21] It is highly desirable to develop an out-of-oven curing methodology that would allow for selective curing and 3D printing of

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“…4). 25,[35][36][37] RF elds have successfully shown composite processing capabilities such as curing of carbon ber (CF) reinforced thermosetting composites and out-of-oven ceramic manufacturing using multiple susceptors. Thermosetting prepregs are fabricated continuously by using energy-expensive methods such as large convection ovens, or infra-red lamps.…”

Section: Volumetric Heatingmentioning

confidence: 99%

“…4 Volumetric RF heating has successfully shown application in (counterclockwise, from top-right) ceramics and carbon fiber composite fabrication, catalytic reactors, thermally driven chemical reactions, and medical applications. 25,[35][36][37] Nanoscale Adv. CNT circuits ten times faster than conventional methods, identifying faulty circuits more reliably.…”

Section: Minireview Nanoscale Advancesmentioning

confidence: 99%

Radio frequency heating and material processing using carbon susceptors

et al. 2021

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Kinetics of carbon nanotube-loaded epoxy curing: Rheometry, differential scanning calorimetry, and radio frequency heating

Cited by 24 publications

References 35 publications

Electronic and Optical Property Control of Polycation/MXene Layer-by-Layer Assemblies with Chemically Diverse MXenes

Electronic and Optical Property Control of Polycation/MXene Layer-by-Layer Assemblies with Chemically Diverse MXenes

Rapid Manufacturing via Selective Radio‐Frequency Heating and Curing of Thermosetting Resins

Radio frequency heating and material processing using carbon susceptors

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