The thermal conductivity of epoxy-resin/metal-powder composite materials from 1.7 to 300K

Abstract

The thermal conductivity of composites made from epoxy-resin Epikote 828 with metal-powder fillers has been measured from 1.7 to 300 K. The metals were Cu, Ag, Au, Al, Sn, Pb, stainless steel and bronze, and in almost all cases the particles were spherical or rounded. At 20 K and above the thermal conductivity is independent of the particle size and is in good agreement with the relation of Meredith and Tobias (extension of Rayleigh's theory). Below 20 K the thermal conductivity of the composite is lower than predicted by the theory especially for specimens containing smaller particles, and it can even be less than that of the unfilled resin. This is due to an acoustic mismatch of the phonons at the resin-particle interfaces. An 'effective particle conductivity' which takes account of this mismatch can be computed, which when incorporated into the theory leads to reasonable agreement with experiment. 100 46 25 11 50 15 48 27 < 40 37 25 92 46 10 46 60 40 ~ ~ ~~~ ~~~~~ t Spherical specimens prepared in laboratory, see text. Spherical particles separated in laboratory, see text.

Effect of Metallic Additives to Polymer Matrix on Properties of Composite Adhesives Dedicated for Light Metal Joining

“…It only resulted in minor changes in the thermal conductivity of the aforementioned composites. The findings of the thermal conductivity research for the composites with polymer matrices and ceramic and metal reinforcements can be found in [2]. For ceramics refer to [3].…”

“…Usually the improvers are the metal powders obtained from copper (Cu), silver (Ag) [2] or ceramics [3]. The main factors determining the choice are not only the physical properties (high thermal conductivity) and mechanical strength but also economic issues.…”

Equivalent inhomogeneity method for evaluating the effective conductivities of isotropic particulate composites

“…In this case the materials with random distribution of particles which possess interfacial resistance are considered. We obtained the results for a cluster of N = 20 particles with conductivities α = k p /k m = 1000, and then compare them to the experimental data of Araujo and Rosenberg [1976], who measured the effective thermal conductivity of random dispersions of metallic spheres in an epoxy matrix. The same data were used by Torquato and Rintoul [1995] to compare their bounds.…”

On the decay of end effects in conduction phenomena: A sandwich strip with imperfect interfaces of low or high conductivity

“…At this kind of an interface, which will be called HC type ͑high conductivity͒, the temperature field is continuous, whereas the normal component of the heat flux undergoes a discontinuity which is proportional to a certain differential expression of the temperature which is called the surface Laplacian and involves surface derivatives only. It should be noted that while the topic of weakly conducting interfaces in composite media has been investigated in the literature for almost two decades ͑Garrett and Rosenberg, 12 De Araujo and Rosenberg, 13 Benveniste and Miloh, 14 Benveniste, 15 Chiew and Glandt, 16 Hasselman and Johnson, 17 Every et al, 18 Torquato and Rintoul, 19 Lipton and Vernescu, 20,21 Lipton, 22 Cheng and Torquato 23 ͒, the study of the counterpart of highly conducting interfaces is a͒ Electronic mail: benben@eng.tau.ac.il extremely recent ͑Torquato and Rintoul, 19 Cheng and Torquato, 24 Lipton, [25][26][27] Miloh and Benveniste,11 and Benveniste and Miloh 28,29 ͒. A description of the interface conditions in both kinds of interfaces is given in Sec.…”