In situ tailoring the hierarchical microstructures in polyethylene films fabricated by thermally induced phase separation via temperature gradient fields

Jia

et al. 2021

Ind. Eng. Chem. Res.

Self Cite

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.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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

Jia

et al. 2021

Ind. Eng. Chem. Res.

Self Cite

“…[55] Figure 7d further demonstrates the evolution of 2D temperature distribution for cross sections of the testing samples during DMTA measurement (at a heating rate of 5 °C min −1 ) with the aid of ETM, which has been proven fairly suitable for the generalized multidimensional phase-change issues previously. [56][57][58][59] It was seen that the material centers' temperature had been always lower than that of the outer surface during the heating process. Besides, the difference in temperature distribution was greatly enlarged by increasing Ni@GNP content, since the internal thermal conductive network structure in the composites became more perfect as the Ni@GNP content increased, helping to realize a uniform internal and external temperature.…”

Section: Dynamical Thermomechanical Behaviormentioning

confidence: 99%

“…In addition, the transient thermal conduction behavior of the composites was also investigated using an ETM, which had been proven to be fairly suitable for generalized multidimensional phasechange issues, and widely adopted to evaluate the heat transfer rates of composites. [57][58][59] The obtained 3D plots of temperature gradient fields are presented in Figure 9, where the dimensionless distance (X) was defined as X = x/b (b: the thickness of samples, x: the distance from samples/heating plate interface). As is shown in Figure 9, the variation trends of temperature over time were generally similar at different locations of the composites, while their specific temperatures were quite different as a matter of fact.…”

Section: Thermal Conductivity and Transient Thermal Conduction Behaviormentioning

confidence: 99%

Polymethyl Methacrylate (PMMA) Nanocomposites Containing Graphene Nanoplatelets Decorated with Nickel Nanoparticles for Electromagnetic Interference (EMI) Shielding and Thermal Management Applications

Jia

et al. 2022

Macro Materials & Eng

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Here, Ni@graphene nanoplatelet (GNP) nanohybrids are obtained via an interfacial reaction growth method and a series of poly(methyl methacrylate) (PMMA)/Ni@GNP composites are prepared by a solution mixing‐ultrasonic dispersion‐hot pressing technology. The influence of Ni@GNP on the electromagnetic interference (EMI) shielding, dielectric, and thermal management behaviors of the composites is intensively investigated. The microcapacitors formed using Ni@GNP as plates and PMMA as matrix significantly improve the dielectric properties of the composites. Enhancement on thermal conduction and EMI properties of PMMA composites with increasing Ni@GNP content can be ascribed to the unique structure of Ni@GNP and it is the filler interconnection network that renders the composite's desirable thermally conductive and thermomechanical properties. A facile way of fabricating polymeric composites with satisfactory thermal conductivity and high‐performance electromagnetic shielding is provided here. The obtained polymer composites display highly promising applications in the thermal management and EMI shielding of electronic devices.

“…wardly via heat conduction. [31][32][33][34] As far as the isothermal platform was concerned, the closer to the glass plate, the more obvious isothermal platform, since the closer to the glass plate, the less easily the latent heat transferred away. On the side of the films close to the cooling medium (X = 0), isothermal platforms were invisible, because of the latent heat released from crystallization process quickly transferred away without any accumulation of excessive heat.…”

Section: Porosity Crystallinity and Wvtr Of The Blend Filmsmentioning

confidence: 99%

Hierarchical structure and properties of high‐density polyethylene (HDPE) microporous films fabricated via thermally‐induced phase separation (TIPS): Effect of presence of ultra‐high molecular weight polyethylene (UHMWPE)

Polymers for Advanced Techs

Wang

Ding³

et al. 2022

Self Cite

In this study, HDPE/UHMWPE microporous films were prepared by blending UHMWPE and HDPE with DOP as the diluent via thermally-induced phase separation (TIPS) method. Morphological studies showed that the phase separation mode of the mixed systems was hardly changed in the presence of UHMWPE. Both average pore size and porosity of the blend films increased firstly and then decreased with increasing UHMWPE content. When UHMWPE content reached 1.5 wt%, both porosity and average pore size of the film reached their maximum values (with a porosity of 84.8% and an average pore size of 0.79 μm). The addition of UHMWPE was found to not only enhance the thermal stability of the HDPE/UHMWPE blend films, but also greatly reduce their thermal shrinkage rate as well as the closed cell temperature, which made the diaphragms containing UHMWPE have good prospect for the application in lithium-ion batteries (LIBs).