Наукові публікації університету

Electrical and thermal conductivity of epoxy nanocomposites with hybrid fillers.

This chapter is dedicated to a synergistic enhancement of electron and thermal conductivities of epoxy-based composites (CMs) with different hybrid fillers. It was shown that combination of carbon fillers with various morphology (1D carbon nanotubes - CNTs, carbon fibers - CFs, 2D graphite nanoplatelets - GNPs) influences a microstructure of composites and leads to a decrease of a percolation threshold and enhancement of an electrical conductivity due to more homogeneous filler dispersion in the epoxy matrix. The addition of the second dielectric filler (hexagonal boron nitride - BN or barium hexaferrite - BaM) into epoxy composites filled with nanocarbon (GNPs or CNTs) lead to a better interconnectivity among fillers in the epoxy matrix, hence, increase of electrical and thermal conductivities. Moreover, the utilizing of the magnetic filler allows preparation of CMs with oriented (or aligned) filler distribution that leads to the anisotropy of physical properties. The results of a numerical modeling of the percolation threshold for CMs with hybrid 1D/2D carbon fillers allowed to establish the relationship between a value of the percolation threshold and size, aspect ratio and mixing ratio of different nanofillers. The electric resistance analysis of our experimental samples under various uniaxial strains and hydrostatic pressures has shown that the change of the filler orientation and an interparticle distance in CMs are responsible for significant changes in a value and temperature dependence of the electrical conductivity of epoxy CMs. The investigations of AC conductivity (up to 10 MHz) of epoxy CMs have shown that tunneling mechanism of the electrical conductivity is prevailing for the CMs with a filler content near the percolation threshold, while for the CMs with a high filler content electric transport is mainly realized via direct contacts between carbon nanoparticles. The results obtained for the thermal conductivity of epoxy composites with single and hybrid filler have shown no indication of the rapid increase for CMs with a filler content higher than the corresponded percolation threshold. These results suggest that a considerable thermal contact resistance might also exist at interfiller contacts. It was found that, compared to carbon nanotubes, GNP particles are the most efficient fillers for an enhancement of the thermal conductivity. This can be explained by a larger surface area and effective interaction of the fillers with the epoxy matrix which results in the formation of a better conductive network. The model of an effective thermal conductivity for carbon-polymer composites based on a mixture model has been proposed. This model takes into account the morphology of a carbon filler, the thermal conductivity of constituents, the thermal contact resistance between filler particles (including interface thermal resistance) and their spatial orientation in a composite. Our investigations of epoxy composites with hybrid fillers have shown the increase of the thermal conductivity as compared to CMs with a single carbon filler. This increase is more pronounced for GNPs/BN fillers. However, the role of an interface thermal resistance is still dominant in the determination of the thermal conductivity of investigated epoxy composites.

ID: 211775
Кількість показів: 27
дата змінення: 04.12.2018 13:51:19
Ким змінено (ім'я): (phys16) Алла Горб
Вид роботи:  Наукова публікація
Тип роботи:  Розділ монографії
Кількість сторінок:  85
Рік видання:  2018
Звітний рік:  2018
Видання:  Nova Science Publishers, Series: Advances in Nanotechnology
Том:  21
Випуск, частина:  Глава 1
Номери сторінок:  1-85
Галузь науки:  Фізика
Автори,співробітники Університету:  Вовченко Людмила Леонітіївна / Мацуй Людмила Юріївна / Перец Юлія Сергіївна / Сагалянов Ігор Юрійович / Яковенко Олена Сергіївна
Кафедра / Відділ:  Загальної фізики / НДЛ Фізичне матеріалознавство твердого тіла
№ теми:   /  / 18БФ051-02
Опубліковано за рішенням Вченої ради:  ні
Інститут/Факультет:  Фізичний факультет

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