Comment on Comment on Anomalous structural recovery in the near glass transition range in a polymer glass: Data revisited in light of temperature variability in vacuum oven-based experiments

Cangialosi, Alegria, and Colmenero have made a comment on a paper of ours [Polym. Eng. Sci. 2022:1-13], in which we discussed the concern that the enthalpy recovery data reported by Cangialosi and co-workers [Phys. Rev. Lett. 2013;111(9):095701] for polystyrene aged up to 15 K below glass transition temperature was anomalous and contradicted existing experimental results from the literature over a similar range of aging conditions. Their response shifts the focus away from the raised questions about their experimental results and attempts to invalidate the data that we cited in support of our argument. Here we respond to the comment and add additional analysis that suggests the structural recovery response of glassy materials exhibits smooth behavior over the full range of measurements, up to 7 or 8 logarithmic decades. We do this by referring to the work on the intrinsic isotherm down-jump and memory responses of poly(vinyl acetate) between 40 degrees C and 15 degrees C over six logarithmic decades by Kovacs [Fortsch. Hochpolym. Fo. 1963;3(1/2):394-508], the small-strain tensile creep of poly(vinyl chloride) quenched from 90 degrees C to 40 degrees C (approximately 40 degrees C below T-g) over seven logarithmic decades from Struik [Polym Eng. Sci., 1977;17:165-173], and the volume recovery behavior for aging times up to 3 months in a temperature range between 95 degrees C and -50 degrees C by Greiner and Schwarzl [Rheol. Acta. 1984;23(4):378-395]. We also add discussion that an isothermal aging procedure using a vacuum oven is highly vulnerable to temperature errors due to the problem of good temperature control when the heat transfer mechanism is primarily radiative.

Automated summary

This article responds to the comment made by Cangialosi, Alegria, and Colmenero on our experimental data and provides additional analysis that suggests a smooth structural recovery behavior of glassy materials within a certain range. It also points out the potential temperature control errors in isothermal aging procedures using a vacuum oven.