Enhanced Thermally Conductive and Microwave Absorbing Properties of Polymethyl Methacrylate/Ni@GNP Nanocomposites

Abstract

In this work, Ni@GNP nanohybrids fabricated via an in situ reduction method were incorporated into polymethyl methacrylate (PMMA) to prepare PMMA/Ni@GNP nanocomposites via solution blending and hot-pressing. The Ni nanoparticles with an average diameter of 70–80 nm were observed to successfully grow on the GNP surface via SEM and TEM. Both thermally conductive and microwave absorbing properties of the prepared composites were intensively investigated. A reflection loss test experimentally suggested that the PMMA/Ni@GNP composites showed a good microwave absorbing property, among which the composite containing 30 wt % Ni@GNP displayed the best microwave absorption performance (with a value of −30 dB for RL min in the C band). The thermal conduction behavior of the composites was jointly studied by infrared thermal imaging (ITI) and enthalpy transformation method together with a four-parameter model. The average heating rate during an initial stage was obviously found to increase from 65.4 to 103.2 °C/min, indicating that a well-defined heat conduction network gradually formed in the composites, which exerted positive influence on heat conduction. The composites generally bore perfect thermal conductivities (e.g., with a maximum in-plane thermal conductivity of 9.02 W/m·K and a maximum out-of-plane value of 1.29 W/m·K), and the variations of thermal conductivity versus filler loading should be attributed to the construction of an anisotropically thermally conductive network in the composites. The PMMA/Ni@GNP composites with desirable microwave absorption and thermal conductivity would find potential applications in 5G communication devices.

Microwave heating of graphene nanoplatelet polymer composites: Experimental and finite element study

“…In‐plane stacking effects of high‐aspect‐ratio graphene platelets in the GNP/PLA nanocomposites can cause the significantly enhanced in‐plane thermal conductivity compared to the through‐thickness direction. Similar trends were reported in References 36 and 46. It should be noted that the SD values of thermal conductivity for all the GNP/PLA nanocomposites was found to be low, that is, a maximum SD of 0.008 and a minimum of 0.001 was seen.…”

Selective Distribution of Filler in PMMA/PLA/BN Thermally Conductive Composites: Theoretical Prediction and Experimental Investigation

“…In order to further reveal the correlation between the microstructure and thermal conductivity of PMMA/PLA/BN composites, thermal diffusivities (α) both in and out of the plane were measured by laser flash method, and the thermal conductivities (TCs, λ) of corresponding samples were obtained using the following formula λ = ρ C normalP α where ρ is the density of the composite and C P is the specific heat. Figure shows the TCs of various composites prepared by the melt blending method (Figure a) and the solution method (Figure b), respectively.…”

A Facile Way of Enhancing Thermally and Electrically Conductive Properties of Epoxy/Ni/GNP Composites via Construction of a Hybrid Filler Network with a Magnetic Field Orientation Technique

“…In order to clearly reveal the relationship between the heating rate and the composite microstructure, experimental results of ITI were compared with non‐linear fitting curves which further disclosed the relationship between dimensionless temperature ( θ ) and logarithm of time (ln t ) with an aid of three‐parameter model (MTPM) equation as follows: [ 44,45 ] $$\begin{equation}\theta = \frac{{{T_0} - T}}{{{T_0} - {T_{\rm{W}}}}}\end{equation}$$where T , T 0 , and T w correspond to the real‐time temperature, initial temperature, and heating medium temperature, respectively. $$\begin{equation} y = {\rm{B}} - \frac{{A + B}}{{1 + {e^{x - {\rm{C}}}}}}\end{equation}$$where y = θ , x = ln t , parameter A is related to initial temperature, parameter B is related to the temperature of heating medium, and parameter C is closely correlated to composites’ properties (composition, filler's content and dispersion state).…”

“…In order to clearly reveal the relationship between the heating rate and the composite microstructure, experimental results of ITI were compared with non-linear fitting curves which further disclosed the relationship between dimensionless temperature (𝜃) and logarithm of time (ln t) with an aid of three-parameter model (MTPM) equation as follows: [44,45]…”