Pressure scanning volumetry

Sonaglioni, Daniele; Tombari, E.; Johari, G. P.

doi:10.1016/j.tca.2022.179319

Cited by 4 publications

(17 citation statements)

References 73 publications

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“…As previously, we use data from studies performed by Andersson and Andersson, who have already provided details of experimental methods as well as the accuracy of the data. − Their papers − may be consulted for details. We digitized their data, constructed the required plots and analyzed those as part of the technique of PSV . Therefore, we begin with our formalism for physical aging in PSV, and analysis of their experimental data …”

Section: Methodsmentioning

confidence: 99%

“…We digitized their data, constructed the required plots and analyzed those as part of the technique of PSV . Therefore, we begin with our formalism for physical aging in PSV, and analysis of their experimental data …”

Section: Methodsmentioning

confidence: 99%

“…DSC scans are routinely used for studies of glass formation and aging of a glass, but PSV scans are rarely used, if at all. As noted previously, Professor Ove Andersson and his group at Umea University (Sweden) in the 1990s developed a computer-controlled pressure-cycling techniques needed for their investigations focused on thermal conductivity of glass-forming liquids and of crystals. − As part of the study, they reported data on the volume of four polymers at a fixed T as p was increased through their p normall → normalg range and also as p was decreased through their p normalg → normall range. They provided isothermal plots of B T against p , showing the p normall → normalg and p normalg → normall ranges and hysteresis of the pressurizing and depressurizing paths.…”

Section: Introductionmentioning

confidence: 99%

“…Since the technique uses the volume data, we named it pressure scanning volumetry (PSV) and by analogy with the DSC scan used to obtain isobaric (d H /d T ) p against T plot, we named the isothermal plot of −(d V /d p ) T against p as PSV scan and showed such scans for atactic poly(propylene) at 297 K. An introduction to PSV is given in Sect. 1 . In that paper, we extended the already successfully used TNM model ,,,− for DSC scans to our PSV scans, obtained the quantities, β, x , and Δ V *, the volume of activation for the characteristic relaxation time, and used these quantities to simulate the PSV scans for pressurizing atactic poly(propylene) melt at 297 K through the p normall → normalg range and depressurizing the glass through the p normalg → normall range.…”

Section: Introductionmentioning

confidence: 99%

“…1 . In that paper, we extended the already successfully used TNM model ,,,− for DSC scans to our PSV scans, obtained the quantities, β, x , and Δ V *, the volume of activation for the characteristic relaxation time, and used these quantities to simulate the PSV scans for pressurizing atactic poly(propylene) melt at 297 K through the p normall → normalg range and depressurizing the glass through the p normalg → normall range. We use the term “simulated” for the plots calculated by using multiple independent parameters and pressurizing and depressurizing rates.…”

Section: Introductionmentioning

confidence: 99%

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Pressure Scanning Volumetry of Physically Aged Polymer Glasses, Fictive Pressure, and Memory Effect

2023

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Physical aging of a glass decreases its volume, V, entropy, and enthalpy, H, toward the equilibrium state values. For glasses usually formed by cooling a melt, the effect is modeled in terms of non-exponential, nonlinear structural relaxation by using a plot of the heat capacity, C p = (dH/dT) p , against T obtained from differential scanning calorimetry (DSC) cooling and heating scans. A melt becomes glass also on isothermal pressurizing and the glass formed becomes liquid on depressurizing, showing a hysteresis of the sigmoid-shape plot of −(dV/dp) T against p, which resembles the thermal hysteresis observed in the C p against T plots. By analogy with DSC, it was named pressure scanning volumetry (PSV). Here, we use the known values of non-exponential and nonlinearity parameters β and x and volume of activation for structural relaxation time, ΔV*, of atactic poly(propylene) to investigate the effect of aging pressure, p age , of aging time, t age , and of the pressurizing rate on aging features in PSV scans. The scans show a post-p g l feature on depressurizing before the −(dV/dp) T overshoot peak appears. We provide quantitative plots (i) of the monotonic decrease of V and increase of fictive pressure, p f , with t age and (ii) of the memory (Kovacs) effect in V and p f of the polymer and (iii) provide generic plots of −(dV/dp) T against p for different combinations of β, x, and ΔV*. The study is of academic significance because PSV scans show a change in the density fluctuation response. It is of technological significance in polymer-extrusion processing and it may stimulate the commercial development of computercontrolled, high-pressure equipment.

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