Abstract
The thermal conductivity and specific heat of epoxy-resin samples made from Epikote 828 resin wth Epikure NMA hardener has been measured from 0.1 to 80K. The samples were produced under various curing conditions. Normally-cured samples (Cure N)-2 h at 100 degrees C followed by 4 h at 200 degrees C; cure A-36 h at 66 degrees C; cure B-1 h at 200 degrees C. Above 2K all samples have the same specific heat but below 2K cures A and B had higher values. The results may be fitted by a density of states model which consists of a constant density of two-level systems plus a Debye spectrum of harmonic states to h(cross) omega /k=8K. The results suggest that cures A and B have about twice as many two-level states as cure N. The phonon spectrum flattens off at h(cross) omega /k=50K and this is to some extent confirmed by Raman scattering experiments. The thermal conductivity of all samples is the same at high temperatures but below 20K that for cure N is about 20% less than for cures A and B. Below 1K it varies at T1.8 and it also shows the plateau typical of glassy materials between 5 and 10K.
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