Athermic process

Creep in technical-purity aluminum at liquid helium temperatures [ ] was noted to be very temperature dependent at 1.4 to 4.2 K, indicating that, even at 4 K, creep is not an athermic process. Creep curves replotted on semilogarithmic coordinates (Fig. 1) suggest that a logarithmic time dependence of the creep is also observable in this temperature range. 

Xi is a dimensionless quantity characterizing the difference between the interaction energy of solvent molecule immersed in the pure polymer compared with interaction energy in the pure solvent. It is a semi-empirical constant. This parameter was introduced by Floiy and Huggins in the equation for solvent activity to extend their theory for athermic processes to the non-athermic processes of mixing ... 

Thus, the mixing of liquids that form an ideal mixture is an athermal process, one in which no heat transfer is needed to keep the temperature constant. 

Whereas the dilution of solutions of AOT reversed micelles at / > 10 is an athermal process (clustering results from topological effects), the dilution of water-lecithin reversed micelles is a strongly endothermic process [52,54], This has been attributed to a strong dependence of the micellar size upon the lecithin... 

The energy of interaction between a pair of solvent molecules, a pair of solute molecules, and a solvent-solute pair must be the same so that the criterion that = 0 is met. Such a mixing process is said to be athermal. The solvent and solute molecules must be the same size so that the criterion... 

Hence, the viscosity of the solution of high-molecular weight polymers substantially decreases on addition of the oligomer salt and the viscometrically determined average degree of association, N, should allow a reliable determination of the equilibrium constant, K, of the athermal mixing process. 

Cohesive energy densities can be used on a limited basis to give quantitative meaning to the chemist s rule of thumb, like dissolves like. Specifically, the more alike a solvent and a polymer are in CED, the more nearly athermal their mixing will be. The more different the two are in this property, the more endothermic the mixing process will be. Remember that Equation (72) makes no provision for exothermic mixing. In the next section we see how such information might be used. Remember that Equation (71) is not limited to endothermic... 

As the crack grows a new surface is being formed. In contrast to this, briefly mentioned athermal rupture, we consider thermal breaking processes according to Eqs. (38) and (39). Since A = o/ /3, the relaxation time r rain depends in an exponential manner on the external stress o. r becomes equivalent to the time required for creep rupturing47. ... 

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