Thermal conductivity enhancement of liquid crystalline epoxy/<scp>MgO</scp> composites by formation of highly ordered network structure

Ota, Saki; Harada, Miyuki

doi:10.1002/app.50367

Cited by 22 publications

(14 citation statements)

References 32 publications

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“…From the statistical results, the thermal conductivity of all models increased with the increasing of temperature. Pure epoxy resin had the lowest thermal conductivity of 0.2147 W/(m·K) at 300 K, and this value was slightly higher than the experimental result (0.21 W/(m·K)) reported in Reference [ 39 ]. The doping of pristine silica into epoxy resin can improve the thermal conductivity to 0.2641 W/(m·K) with a small increase ratio of 23.1%.…”

Section: Resultscontrasting

confidence: 54%

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

Zhang

Wang

et al. 2021

Polymers

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To study the effect of hyperbranched polyester with different kinds of terminal groups on the thermomechanical and dielectric properties of silica–epoxy resin composite, a molecular dynamics simulation method was utilized. Pure epoxy resin and four groups of silica–epoxy resin composites were established, where the silica surface was hydrogenated, grafted with silane coupling agents, and grafted with hyperbranched polyester with terminal carboxyl and terminal hydroxyl, respectively. Then the thermal conductivity, glass transition temperature, elastic modulus, dielectric constant, free volume fraction, mean square displacement, hydrogen bonds, and binding energy of the five models were calculated. The results showed that the hyperbranched polyester significantly improved the thermomechanical and dielectric properties of the silica–epoxy composites compared with other surface treatments, and the terminal groups had an obvious effect on the enhancement effect. Among them, epoxy composite modified by the hyperbranched polyester with terminal carboxy exhibited the best thermomechanical properties and lowest dielectric constant. Our analysis of the microstructure found that the two systems grafted with hyperbranched polyester had a smaller free volume fraction (FFV) and mean square displacement (MSD), and the larger number of hydrogen bonds and greater binding energy, indicating that weaker strength of molecular segments motion and stronger interfacial bonding between silica and epoxy resin matrix were the reasons for the enhancement of the thermomechanical and dielectric properties.

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Section: Resultscontrasting

confidence: 54%

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

Zhang

Wang

et al. 2021

Polymers

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“…The reason may probably be related to the higher thermal conductivity of the magnesium oxide particles. [25] Similarly, Rafiee et al [46] associated the higher weight loss of the modified epoxy with the additives having better thermal conductivity within the matrix system.…”

Section: Thermal Characterizationmentioning

confidence: 99%

“…[19][20][21] Although it has attractive features, the researchers primarily investigated the effect of magnesia on the dielectric and thermal properties of the polymer matrix. [9,20,[22][23][24] Ota and Harada [25] significantly improved the thermal conductivity of the epoxy matrix by modifying it with MgO microparticles. Hornak et al [23] dispersed MgO particles into epoxy at various weight fractions and optimized the dielectric properties of the modified polymer composite with 1 wt% addition of MgO.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and thermal characterization of laminar carbon/epoxy composites modified with magnesium oxide microparticles

Uzay

2021

Polymer Composites

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This paper investigates the effects of magnesium oxide (MgO) microparticles on the mechanical and thermal properties of laminated carbon fiber reinforced polymer composites. The polymer epoxy matrix was modified with 0% (pure), 2 wt%, and 4 wt% MgO fillers. Then the laminar composites were manufactured with the vacuum bag method. The energy absorption capacity and impact strength were determined from the Charpy impact tests, whereas the flexural characteristics were evaluated by conducting three-point bending experiments. Scanned electron microscopy was used to examine both the dispersion of microparticles and the fracture surface of experimentally tested specimens. Thermal performance of the polymer composites with and without MgO additives was analyzed comparatively by performing the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The decomposition temperatures and glass transition temperatures of the composites were obtained. Approximately 30% increment in impact strength was achieved thanks to the MgO fillers. However, although the flexural strength decreased since the MgO particles caused stress concentration, the flexural modulus was not affected due to the decrease of elongation at break. The TGA and DSC instrumentations showed that the decomposition temperatures increased, and curing behaviors were improved depending upon the MgO content.

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“…Researchers usually control physical structures by optimal design of molecular structures to enhance intrinsic λ of polymer matrix [16][17][18]. One recognized method is to embed liquid crystal units in molecular structure to make molecular chains arrange orderly, so that the heat flow could conduct along the direction of ordered chains, which effectively suppresses phonon scattering and improves thermal conductivity of polymer matrix [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Zhong

Ruan

2022

Research

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Enhancing thermal conductivity coefficient ( λ ) of liquid crystal polyesters would further widen their application in electronics and electricals. In this work, a kind of biphenyl-based dihydroxy monomer is synthesized using 4, 4’-biphenyl (BP) and triethylene glycol (TEG) as raw material, which further reacts with three different dicarboxylic acids (succinic acid, p-phenylenediacetic acid, and terephthalic acid, respectively) by melt polycondensation to prepare intrinsically highly thermally conductive poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) succinate (PEOS), poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) p-phenyldiacetate (PEOP) and poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) terephthalate (PEOT), collectively called biphenyl-based liquid crystal polyesters (B-LCPE). The results show that B-LCPE possess the desired molecular structure, exhibit smectic phase in liquid crystal range and semicrystalline polymers at room temperature, and possess excellent intrinsic thermal conductivities, thermal stabilities, and mechanical properties. λ of PEOT is 0.51 W/(m·K), significantly exceeds that of polyethylene terephthalate (0.15 W/(m·K)) which has similar molecular structure with PEOT, and also higher than that of PEOS (0.32 W/(m·K)) and PEOP (0.38 W/(m·K)). The corresponding heat resistance index ( T HRI ), elasticity modulus, and hardness of PEOT are 174.6°C, 3.6 GPa, and 154.5 MPa, respectively, and also higher than those of PEOS (162.2°C, 1.8 GPa, and 83.4 MPa) and PEOP (171.8°C, 2.3 GPa, and 149.6 MPa).

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Thermal conductivity enhancement of liquid crystalline epoxy/MgO composites by formation of highly ordered network structure

Cited by 22 publications

References 32 publications

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

Mechanical and thermal characterization of laminar carbon/epoxy composites modified with magnesium oxide microparticles

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

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