Thermal Conductivity Of Epoxy Nanocomposites Research Articles

Model Approach to Thermal Conductivity in Hybrid Graphene-Polymer Nanocomposites.

The thermal conductivity of epoxy nanocomposites filled with self-assembled hybrid nanoparticles composed of multilayered graphene nanoplatelets and anatase nanoparticles was described using an analytical model based on the effective medium approximation with a reasonable amount of input data. The proposed effective thickness approach allowed for the simplification of the thermal conductivity simulations in hybrid graphene@anatase TiO2 nanosheets by including the phenomenological thermal boundary resistance. The sensitivity of the modeled thermal conductivity to the geometrical and material parameters of filling particles and the host polymer matrix, filler's mass concentration, self-assembling degree, and Kapitza thermal boundary resistances at emerging interfaces was numerically evaluated. A fair agreement of the calculated and measured room-temperature thermal conductivity was obtained.

Anisotropy induced in magnetic field in GNPs/epoxy composites used as an effective heat dissipation electronic packaging material

AbstractThis article investigates the effect of different magnetic fields on modulating the alignment of graphene nanoplatelets (GNPs) and their impact on the thermal conductivity of epoxy nanocomposites. Various nanocomposite specimens were fabricated with different GNP contents by using magnetically field‐aligned GNPs in the fabrication process to enhance the thermal conductivity. The results showed that the in‐plane thermal conductivity of the Bmf (Bidirectional magnetic field) sample with 5 wt% GNPs added reached 0.75 W m−1 K−1, which is 276.6% higher than that of pure epoxy resin and the anisotropy coefficient (K∥/K⊥) reached 3.3. In addition, temperature rise tests were performed to simulate the thermal conductivity of nanocomposites used as an electronic packaging material, and the results indicated that the composites achieved a significant increase in in‐plane thermal conductivity with a lower amount of filler. This provides valuable insights into the preparation of thermally conductive composites and demonstrates their potential as a thermal management packaging material for next‐generation electronic devices.

Improved Thermal Conductivity and Thermomechanical Properties of Epoxy Nanocomposites with Branched Polyethyleneimine‐Functionalized Hexagonal Boron Nitride Nanosheets

AbstractIn this present, branched polyethyleneimine (BPEI)‐functionalized hexagonal boron nitride nanosheets (BNNS) were employed to improve the thermal conductivity and thermomechanical properties of epoxy resin. The 3‐glycidyloxypropyltrimethoxysilane (KH560)‐modified BNNS were firstly prepared via one‐step ball milling, and then reacted with BPEI to obtain BPEI‐functionalized BNNS (BPEI‐KH560‐BNNS). Results showed that, compared with neat epoxy resin, the thermal conductivity of epoxy nanocomposite filled with BPEI‐KH560‐BNNS increased by 189.8 % at 10 wt %, which is also higher than that of the epoxy nanocomposites filled with BN particles, BNNS and KH560‐BNNS. Besides, the highest storage modulus (3.23 GPa) and glass transition temperature (161.7 °C) were also achieved in 10 wt % BPEI‐KH560‐BNNS/epoxy nanocomposite, which increased 39.2 % and 20.9 °C respectively. This is mainly ascribed that the abundant amino groups on BPEI molecular chain can improve the interfacial compatibility and bonding strength between BN nanofillers and epoxy matrix, which has been observed in the morphology of the fracture surface of epoxy nanocomposites. This work provides an effective strategy for improving the thermal conductivity and thermomechanical properties of epoxy resin.

Synthesis of KH550-Modified Hexagonal Boron Nitride Nanofillers for Improving Thermal Conductivity of Epoxy Nanocomposites.

In this work, KH550 (γ-aminopropyl triethoxy silane)-modified hexagonal boron nitride (BN) nanofillers were synthesized through a one-step ball-milling route. Results show that the KH550-modified BN nanofillers synthesized by one-step ball-milling (BM@KH550-BN) exhibit excellent dispersion stability and a high yield of BN nanosheets. Using BM@KH550-BN as fillers for epoxy resin, the thermal conductivity of epoxy nanocomposites increased by 195.7% at 10 wt%, compared to neat epoxy resin. Simultaneously, the storage modulus and glass transition temperature (Tg) of the BM@KH550-BN/epoxy nanocomposite at 10 wt% also increased by 35.6% and 12.4 °C, respectively. The data calculated from the dynamical mechanical analysis show that the BM@KH550-BN nanofillers have a better filler effectiveness and a higher volume fraction of constrained region. The morphology of the fracture surface of the epoxy nanocomposites indicate that the BM@KH550-BN presents a uniform distribution in the epoxy matrix even at 10 wt%. This work guides the convenient preparation of high thermally conductive BN nanofillers, presenting a great application potential in the field of thermally conductive epoxy nanocomposites, which will promote the development of electronic packaging materials.

Effects of MWCNTs on the Tensile Properties and Thermal Conductivity of BaTiO3 /Epoxy Nanocomposites

This research studied the effects of modified BaTiO3 (BT) nanoparticles with coupling agent γ-APS (0.5wt. %) on the tensile and thermal conductivity of epoxy nanocomposites with respect to content (0.25, 0.5, 0.75, 1, 3 and 5wt. %). Multiwall carbon nanotubes (MWCNTs) at different concentration (0.2, 0.4, 0.8 and 1 wt. %) were added to the BaTiO3/epoxy nanocomposites. The influence of MWCNTs on the tensile properties and thermal conductivity was investigated. The tensile strength and Young’s modulus of BaTiO3/epoxy nanocomposites film were increased at up to 3 wt. % of added BT, but adding BT at more than 3 wt.% decreased the strength of epoxy. The tensile strength was increased with increasing MWCNTs content from 32 MPa for pure epoxy to the value 56.8 MPa for 1wt. % of MWCNTs content. The thermal conductivity of BaTiO3/epoxy nanocomposites improved with increase of BT content. At 3wt. % and 5wt. % of BaTiO3 the thermal conductivity of nanocomposites decreased. The increase of MWCNTs concentration from 0.2 wt. % to 1 wt. % resulted in a thermal conductivity enhancement.

Epoxy nanocomposites with high thermal conductivity and low loss factor: Realize 3D thermal conductivity network at low content through core-shell structure and micro-nano technology

Dielectric polymers with high thermal conductivity are very promising in the fields of aerospace and electronic device packaging. However, composites with excellent dielectric properties usually have low thermal conductivity. It is usually to fill the polymer with thermal conductivity particles to improve the thermal conductivity, but the high content of filler often reduces the mechanical properties of the polymer. In this paper, the traditional insulating polymer epoxy resin was used as the matrix, by covering the surface of silicon carbide with graphene to form a core-shell structure and co-filled with nano diamonds to achieve the preparation of high-performance epoxy resin at low content. The results showed that at the filling content of 30 wt%, the thermal conductivity of epoxy nanocomposites showed a dramatic thermal conductivity enhancement of 1263%, the energy storage modulus increased by 1.1 GPa, and the dielectric loss remained unchanged at 50 Hz. The advantages of the composite are the structural design and surface modification of the filler, which not only take advantage of its inherent advantages, but also improve the interface area with the epoxy matrix. The composite materials with excellent properties are expected to provide theoretical guidance for the application of high thermal conductivity dielectric materials.

A physics investigation for influence of carbon nanotube agglomeration on thermal properties of composites

In the present study, a micromechanics model is developed to investigate the thermal properties of nanocomposites with agglomerated fibers. This paper mainly analyzes the influence of carbon nanotube (CNT) agglomeration on the thermal expansion coefficients and thermal conductivity of epoxy nanocomposites based on the micromechanical theory proposed. The agglomeration of CNTs in epoxy matrix is divided into two parts: the regions with high concentrations of CNTs; the regions with low concentrations of CNTs. The analytical expressions are derived according to the micromechanics method, and the two aggregation parameters are introduced to analyze the effect of CNTs agglomerated. The influences of high and low CNT agglomerations on the thermal expansion coefficients and thermal conductivity of composites are investigated, respectively. It is shown that the non-uniform dispersion of CNTs in matrix has a significant influence on the thermal expansion coefficients and thermal conductivity of nanocomposites.

Synthesis and Characterization of Functionalized Fe3O4/Boron Nitride as Magnetically Alignable 2D-Nanofiller to Improve the Thermal Conductivity of Epoxy Nanocomposites

In the electronic industry, there is an enormous request for high thermal conductivity polymer. In this regard, we propose a novel synthesis route to produce magnetically alignable 2D-nanofiller. In our work, surface modification of boron nitride nanosheets (BNNs) with polyacrylamide brushes are explored. For this purpose, the post-polymerization reaction of BNNs is followed by the redox polymerization of acrylamide onto the surfaces of already hydroxyl-functionalized BNNs. Afterward, magnetic iron oxide nanoparticles are contributed to modified BNNs through polyacrylamide chelating effect. Finally, to provide high thermal conductive and magnetic responsive nanocomposites, the functionalized Fe3O4/BNNs are dispersed in epoxy matrix and aligned under an external magnetic field. According to the results of thermal conductivity studies, thermal transport of the nanocomposites increases to 0.37 W/mK by adding only 10% of functionalized Fe3O4/BNNs (at 25 °C). Mechanical and thermal properties of these nanocomp...

Experimental evaluation and modeling of thermal conductivity of tetrafunctional epoxy resin containing different carbon nanostructures

This study attempts to investigate the thermal conductivity behavior of epoxy nanocomposites containing different types of nanofillers, such as 1‐D Multiwall Carbon Nanotubes (MWCNTs) and 2‐D predominant shape of Exfoliated Graphite nanoparticles (EG) at loading level from 0.25 to 3% wt. For all the analyzed epoxy nanocomposites calorimetric investigation shows that EG nanoparticles accelerate the curing process of the epoxy resin. Thermal conductivity measurements show that this acceleration is directly related to the better heat conduction obtained through the incorporation of EG in the epoxy matrix. The thermal conductivity of epoxy nanocomposites filled with EG, unlike of epoxy nanocomposites containing MWCNTs, increases significantly with increasing content of nanofiller. An increase in thermal conductivity of ∼ 300% has been detected for a filler percentage of only 3%wt of EG.The application of Deng‐Zheng micromechanical model has proven to be very effective in predicting analytically the thermal conductivity of the analyzed nanocomposites. POLYM. ENG. SCI., 57:779–786, 2017. © 2017 Society of Plastics Engineers

A novel approach to enhance the thermal conductivity of epoxy nanocomposites using graphene core–shell additives

We report on a novel technique to enhance the thermal conductivity of epoxy nanocomposites using graphene coated poly-methyl-methacrylate (PMMA) balls. PMMA balls with a diameter in the range of 200–300 nm were synthesized using suspension polymerization. These balls were coated with chemically reduced graphene oxide to form a core–shell additive and dispersed in epoxy. Thermal conductivity measurements of bulk samples of graphene-coated PMMA (GPMMA) epoxy nanocomposite were carried out and compared with baseline samples comprised of graphene nanosheets (not in the core–shell form) dispersed in the epoxy resin. Results show that the addition of 1% (by weight) GPMMA balls increases thermal conductivity by 7-fold. By contrast, the addition of 1% (by weight) of graphene nanosheets (not in the core–shell form) only improves thermal conductivity of the nanocomposite by approximately 3-fold. We attribute this improvement in thermal performance to more uniform dispersion and improved phonon conduction pathways for the GPMMA core–shell additive.

Thermal conductivity of epoxy resins filled with MWCNT and hydrotalcite clay: Experimental data and theoretical predictive modeling

In this work, the effect of hydrotalcite clay on the thermal conductivity of epoxy resin filled with carbon nanotubes (CNTs) has been studied. Thermal and morphological experiments show that the presence of hydrotalcite clay in a mesh of carbon nanotubes gives rise to aggregates and twisted bundles, resulting in a lower thermal conductivity of epoxy nanocomposites. Simple model for evaluation of the thermal conductivity of the composites is presented as analytical function of volume fraction, anisotropic thermal conductivities, aspect ratio, non‐straightness, and interfacial thermal resistance of the CNTs. The model predictions agree very well with the measured thermal conductivities of epoxy nanocomposites and confirm the hypothesis that the presence of a clay in a mesh of nanotubes results in a lower elongation of CNT. POLYM. COMPOS., 36:1118–1123, 2015. © 2014 Society of Plastics Engineers

Modeling the thermal conductivity of polymeric composites based on experimental observations

One approach to increase the low thermal conductivity of polymers is to add nanosized or microsized fillers with relatively high thermal conductivity. The concept of nanodielectrics is based on the fact that the dielectric behaviour of polymeric composites is tailored on or dictated by nanoscale manipulation. In this paper, the role of fillers in the thermal conductivity of polymeric composites is investigated and reference is made to a number of different studies. The main goal is to determine potential trends governing or dictating the process of thermal conduction in polymeric composites including nanocomposites and microcomposites. Shape, size and thermal conductivity are some of the particle properties considered. Also, the crucial role of interfaces and agglomerations of particles is discussed. Finally, three dimensional models are implemented in Comsol Multiphysics in order to demonstrate the experimental observations and fit the experimental results on the thermal conductivity of epoxy nanocomposites.

Thermal Conductivity of Epoxy Resin Reinforced with Magnesium Oxide Coated Multiwalled Carbon Nanotubes

Magnesium oxide coated multiwalled carbon nanotubes (MgO@MWNT) were fabricated and dispersed into epoxy matrix. The microstructures of MgO@MWNT and epoxy/MgO@MWNT nanocomposites were characterized by TEM and SEM. Electrical resistivity and thermal conductivity of epoxy nanocomposites were investigated with high resistance meter and thermal conductivity meter, respectively. MgO@MWNT has core-shell structure with MgO as shell and nanotube as core, and the thickness of MgO shell is ca. 15 nm. MgO@MWNT has been dispersed well in the epoxy matrix. MgO@MWNT loaded epoxy nanocomposites still retain electrical insulation inspite of the filler content increase. However, thermal conductivity of epoxy was increased with the MgO@MWNT content increasing. When MgO@MWNT content reached 2.0 wt.%, thermal conductivity was increased by 89% compared to neat epoxy, higher than that of unmodified MWNT nanocomposites with the same loading content.

Enhanced thermal conductivity of epoxy nanocomposites filled with hybrid filler system of triethylenetetramine-functionalized multi-walled carbon nanotube/silane-modified nano-sized silicon carbide

Multi-walled carbon nanotubes (MWCNTs) were first treated by a 3:1 (v/v) mixture of concentrated H 2SO 4/HNO 3, and then triethylenetetramine (TETA) grafting was carried out. Nano-sized silicon carbide particles (SiC np) were modified by the silane coupling agent. Epoxy nanocomposites filled with hybrid filler system containing TETA-functionalized MWCNTs and silane-modified SiC np were prepared. The investigation on the thermal conductivity of epoxy nanocomposites filled with single filler system and hybrid filler system was performed. Chemical surface treatment is conducive to the enhancement of thermal conductivity of epoxy composites. The thermal conductivity of epoxy composites with hybrid filler system is higher than that of epoxy composites with any single filler system (functionalized MWCNTs or modified SiC np), which is due to the effective combination of MWCNT-to-MWCNT and SiC np-to-SiC np conductive networks. Hybrid filler system could provide synergistic effect and cost reduction simultaneously.

The effects of triethylenetetramine grafting of multi‐walled carbon nanotubes on its dispersion, filler‐matrix interfacial interaction and the thermal properties of epoxy nanocomposites

AbstractThis study describes the influence of triethylenetetramine (TETA) grafting of multi‐walled carbon nanotubes (MWCNTs) on the dispersion state, interfacial interaction, and thermal properties of epoxy nanocomposites. MWCNTs were first treated by a 3:1 (v/v) mixture of concentrated H2SO4/HNO3, and then TETA grafting was performed. Chemically grafted MWCNT/bisphenol‐A glycidol ether epoxy resin/2‐ethyl‐4‐methylimidazole nanocomposites were prepared. TETA grafting could establish the connection of MWCNTs to the epoxy matrix and transform the smooth and nonreactive MWCNT surface into a hybrid material that possesses the characteristics of both MWCNTs and TETA, which facilitates homogeneous dispersion of MWCNTs and improves nanotube‐epoxy interfacial interaction. Therefore, the impact property, glass transition temperature, thermal stability, and thermal conductivity of epoxy nanocomposites are enhanced. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers