The Low-Temperature Thermal Conductivity of Rubber
There have recently been a number of studies of the temperature dependence of the thermal conductivity, κ, of semicrystalline polymers including the influence of (a) the degree of crystallinity1,2 and (b) the crystallite orientation3,4. The general result of these measurements which we reviewed in an earlier ICM conferences is that above and below ~20K the variation of κ with the two parameters is completely different. At the higher end of the range conductivity increases both with increasing crystallinity and the degree of orientation. At low temperatures, on the other hand, the specimens with the highest crystallinity have the lowest conductivity with values at ~2K roughly an order of magnitude lower than those found “universally” in all amorphous polymers6. This behaviour has also been observed in araldite containing powdered crystalline additives. For the semicrystalline polymers the low-temperature data are also found to be essentially independent of the degree of crystallite orientation.
KeywordsCarbon Black Natural Rubber High Density Polyethylene Extrusion Direction Semicrystalline Polymer
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