Elastic Properties of Cork: II. Stress-Temperature Relationship of Compressed Cork

In the first paper of this series it was shown that for cork, held at constant compression, the stress as a function of compression, temperature, and time was separable into two factors, one factor representing the load-compression curve and the other describing the decay of stress with time. In the present paper the dependence of the load-compression curve upon temperature is studied. After the sample has relaxed at constant temperature and compression for a time sufficiently long so that the change of stress with time may be neglected, stress-temperature curves were obtained. These curves showed a linear dependence of the stress upon the temperature. From the stress-temperature curves the resolution of the stress into its additive components due to internal energy and entropy was carried out. The physical significance of this resolution is discussed. The experiments were carried out with a refined version of the apparatus described in the first paper. In particular, the apparatus was corrected for rate of thermal expansion.