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Article

Densification: A Route towards Enhanced Thermal Conductivity of Epoxy Composites

Departament de Màquines i Motors Tèrmics, ESEIAAT, Universitat Politècnica de Catalunya, C/Colom 11, 08222 Terrassa, Spain
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Polymers 2021, 13(2), 286; https://doi.org/10.3390/polym13020286
Received: 13 December 2020 / Revised: 12 January 2021 / Accepted: 13 January 2021 / Published: 17 January 2021
(This article belongs to the Special Issue Polymer-Inorganic Composites for Special Applications)
When an amorphous polymer is cooled under pressure from above its glass transition temperature to room temperature, and then the pressure is released, this results in a densified state of the glass. This procedure applied to an epoxy composite system filled with boron nitride (BN) particles has been shown to increase the density of the composite, reduce its enthalpy, and, most importantly, significantly enhance its thermal conductivity. An epoxy-BN composite with 58 wt% BN platelets of average size 30 µm has been densified by curing under pressures of up to 2.0 MPa and then cooling the cured sample to room temperature before releasing the pressure. It is found that the thermal conductivity is increased from approximately 3 W/mK for a sample cured at ambient pressure to approximately 7 W/mK; in parallel, the density increases from 1.55 to 1.72 ± 0.01 g/cm3. This densification process is much more effective in enhancing the thermal conductivity than is either simply applying pressure to consolidate the epoxy composite mixture before curing or applying pressure during cure but then removing the pressure before cooling to room temperature; this last procedure results in a thermal conductivity of approximately 5 W/mK. Furthermore, it has been shown that the densification and corresponding effect on the thermal conductivity is reversible; it can be removed by heating above the glass transition temperature and then cooling without pressure and can be reinstated by again heating above the glass transition temperature and then cooling under pressure. This implies that a densified state and an enhanced thermal conductivity can be induced even in a composite prepared without the use of pressure. View Full-Text
Keywords: thermal conductivity; epoxy composites; boron nitride; densification; glass transition; differential scanning calorimetry (DSC) thermal conductivity; epoxy composites; boron nitride; densification; glass transition; differential scanning calorimetry (DSC)
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MDPI and ACS Style

Moradi, S.; Román, F.; Calventus, Y.; Hutchinson, J.M. Densification: A Route towards Enhanced Thermal Conductivity of Epoxy Composites. Polymers 2021, 13, 286. https://doi.org/10.3390/polym13020286

AMA Style

Moradi S, Román F, Calventus Y, Hutchinson JM. Densification: A Route towards Enhanced Thermal Conductivity of Epoxy Composites. Polymers. 2021; 13(2):286. https://doi.org/10.3390/polym13020286

Chicago/Turabian Style

Moradi, Sasan, Frida Román, Yolanda Calventus, and John M. Hutchinson 2021. "Densification: A Route towards Enhanced Thermal Conductivity of Epoxy Composites" Polymers 13, no. 2: 286. https://doi.org/10.3390/polym13020286

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