scholarly journals Temperature-Triggered/Switchable Thermal Conductivity of Epoxy Resins

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 65
Author(s):  
Matthias Sebastian Windberger ◽  
Evgenia Dimitriou ◽  
Sarah Rendl ◽  
Karin Wewerka ◽  
Frank Wiesbrock
Keyword(s):  
Thermal Conductivity ◽  
Polymer Networks ◽  
Diglycidyl Ether ◽  
Epoxy Compound ◽  
Inorganic Materials ◽  
Glass Transition Point ◽  
Limiting Factor ◽  
Epoxy Amine ◽  
Π Stacking ◽  
Enhanced Thermal Conductivity

The pronouncedly low thermal conductivity of polymers in the range of 0.1–0.2 W m−1 K−1 is a limiting factor for their application as an insulating layer in microelectronics that exhibit continuously higher power-to-volume ratios. Two strategies can be applied to increase the thermal conductivity of polymers; that is, compounding with thermally conductive inorganic materials as well as blending with aromatic units arranged by the principle of π-π stacking. In this study, both strategies were investigated and compared on the example of epoxy-amine resins of bisphenol A diglycidyl ether (BADGE) and 1,2,7,8-diepoxyoctane (DEO), respectively. These two diepoxy compounds were cured with mixtures of the diamines isophorone diamine (IPDA) and o-dianisidine (DAN). The epoxy-amine resins were cured without filler and with 5 wt.-% of SiO2 nanoparticles. Enhanced thermal conductivity in the range of 0.4 W·m−1·K−1 was observed exclusively in DEO-based polymer networks that were cured with DAN (and do not contain SiO2 fillers). This observation is argued to originate from π-π stacking of the aromatic units of DAN enabled by the higher flexibility of the aliphatic carbon chain of DEO compared with that of BADGE. The enhanced thermal conductivity occurs only at temperatures above the glass-transition point and only if no inorganic fillers, which disrupt the π-π stacking of the aromatic groups, are present. In summary, it can be argued that the bisphenol-free epoxy-amine resin with an epoxy compound derivable from natural resources shows favorably higher thermal conductivity in comparison with the petrol-based bisphenol-based epoxy/amine resins.

scholarly journals Bisphenol-Free Epoxy Resins Derived from Natural Resources Exhibiting High Thermal Conductivity

Proceedings ◽  
2020 ◽  
Vol 69 (1) ◽  
pp. 18
Author(s):  
Matthias Sebastian Windberger ◽  
Evgenia Dimitriou ◽  
Frank Wiesbrock
Keyword(s):  
Thermal Conductivity ◽  
Natural Resources ◽  
Polymer Networks ◽  
Sio2 Nanoparticles ◽  
Diglycidyl Ether ◽  
Epoxy Compound ◽  
Inorganic Materials ◽  
Limiting Factor ◽  
Epoxy Amine ◽  
Π Stacking

Polymers commonly have low thermal conductivity in the range of 0.1–0.2 W·m−1·K−1, which is a limiting factor for their usage in the course of continuously increasing miniaturization and heat generation in electronic applications. Two strategies can be applied to increase the transport of phonons in polymers: (i) the embedment of thermally conductive inorganic materials and (ii) the involvement of aromatic units enabling anisotropy by π–π stacking. In this study, the thermal conductivity of resins based on bisphenol A diglycidyl ether BADGE and 1,2,7,8-diepoxyoctane DEO was compared. DEO can be derived from pseudo-pelletierine, which is contained in the bark of the pomegranate tree. The epoxy compounds were cured with isophorone diamine IPDA, o-dianisidine DAN, or mixtures of the both diamines. Notably, isophorone diamine is derived from isophorone of which the latter naturally occurs in cranberries. The formulations were produced without filler or with 5 wt.-% of SiO2 nanoparticles. Significantly enhanced thermal conductivity in the range of 0.4 W·m−1·K−1 occurs only in DEO-based polymer networks that were cured with DAN (and do not contain SiO2 fillers). This observation is argued to originate from π–π stacking of the aromatic units of DAN enabled by the higher flexibility of the aliphatic carbon chain of DEO compared to that of BADGE. This assumption is further supported by the facts that significantly improved thermal conductivity occurs only above the glass-transition temperature and that nanoparticles appear to disrupt the π–π stacking of the aromatic groups. In summary, it can be argued that the bisphenol-free epoxy/amine resin with an epoxy compound derivable from natural resources shows favorably higher thermal conductivity in comparison to the petrol-based epoxy/amine resins.

scholarly journals Enhanced Thermal Conductivity and Mechanical Toughness of the Epoxy Resin by Incorporation of Mesogens Without Nanofillers

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 31575-31580
Author(s):  
Kaiyi Tian ◽  
Senyuan Yang ◽  
Jiaxuan Niu ◽  
Hanxiang Wang
Keyword(s):  
Thermal Conductivity ◽  
Epoxy Resin ◽  
Enhanced Thermal Conductivity

Enhanced thermal conductivity of composite phase change materials based on carbon modified expanded perlite

2021 ◽  
Vol 261 ◽  
pp. 124226
Author(s):  
Runjie Li ◽  
Yajing Zhao ◽  
Boyang Xia ◽  
Zhensheng Dong ◽  
Song Xue ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Expanded Perlite ◽  
Composite Phase Change Materials ◽  
Enhanced Thermal Conductivity

scholarly journals Thermoelectric Materials for Textile Applications

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3154
Author(s):  
Kony Chatterjee ◽  
Tushar K. Ghosh
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Seebeck Coefficient ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Inorganic Materials ◽  
Peltier Effect ◽  
Electronic Textiles ◽  
Heating And Cooling ◽  
Recent Attention

Since prehistoric times, textiles have served an important role–providing necessary protection and comfort. Recently, the rise of electronic textiles (e-textiles) as part of the larger efforts to develop smart textiles, has paved the way for enhancing textile functionalities including sensing, energy harvesting, and active heating and cooling. Recent attention has focused on the integration of thermoelectric (TE) functionalities into textiles—making fabrics capable of either converting body heating into electricity (Seebeck effect) or conversely using electricity to provide next-to-skin heating/cooling (Peltier effect). Various TE materials have been explored, classified broadly into (i) inorganic, (ii) organic, and (iii) hybrid organic-inorganic. TE figure-of-merit (ZT) is commonly used to correlate Seebeck coefficient, electrical and thermal conductivity. For textiles, it is important to think of appropriate materials not just in terms of ZT, but also whether they are flexible, conformable, and easily processable. Commercial TEs usually compromise rigid, sometimes toxic, inorganic materials such as bismuth and lead. For textiles, organic and hybrid TE materials are more appropriate. Carbon-based TE materials have been especially attractive since graphene and carbon nanotubes have excellent transport properties with easy modifications to create TE materials with high ZT and textile compatibility. This review focuses on flexible TE materials and their integration into textiles.

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