Polymer glasses, aging

L. Buisson, S. Ciliberto, and A. Garcimartin, Intermittent origin of the large violations of the fluctuation-dissipation relations in an aging polymer glass. Europhys. Lett. 63, 603 (2003). 

Some of the most important early experimental observations were of transitions from the quasi-brittle crazing deformation mode to the ductile shear deformation mechanisms with changes in the experimental conditions, such as temperature and strain rate, as well as in polymer variables, such as polymer backbone architecture, blend composition, crosslinking and physical aging state of the polymer glass. One of the strengths of the model of craze growth outlined above is that it allows one to make sense out of some experimentally observed craze-to-shear transitions that had previously defied explanation . The idea behind this explanation is quite simple One writes an expression for the shear yield stress, viz ... 

Bellon L, Ciliberto S, I,aroche C (2002) Advanced memory effects in the aging of a polymer glass. Eur Phys J B 25 223-231... 

Fukao K, Yamawaki S (2007) Crossover of aging dynamics in polymer glass from cumulative aging to noncumulative aging. Phys Rev E 76 021507... 

Fukao K, Tahara D (2009) Aging dynamics in the polymer glass of poly(2-chlorostyrene) dielectric susceptibility and volume. Phys Rev E 80 051802... 

Robertson, R. E., Simha, R., and Curro, J. G., Multiple temperature steps a further test of an aging theory for polymer glasses. Macromolecules, 21,3216-3220 (1988). 

Robertson et al. [1984] developed a stochastic model for predicting the kinetics of physical aging of polymer glasses. The equilibrium volume at a given temperature, the hole fraction, and the fluctuations in free volume were derived from the S-S cell-hole theory. The rate of volume changes was assumed to be related to the local free volume content thus, it varied from one region to the next according to a probability function. The model predictions compared favorably with the results from Kovacs laboratory. Its evolution and recent advances are discussed by Simha and Robertson in Chapter 4. 

Kluin, J. E., Moaddel, H., Ruan, M. Y, Yu, Z., Jamieson, A. M., Simha, R., McGervey, J. D., Probe spectroscopy, free-volume concepts, and physical aging of polymer glasses, in Structure-property relations in polymers, Adv. Chem. Ser, 236, Chapter 20, pp. 535 (1993). 

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