An isothermal scanning calorimeter controlled by linear pressure variations from 0.1 to 400 MPa. Calibration and comparison with the piezothermal technique

Abstract

An isothermal scanning calorimeter controlled by linear pressure variations is described for the pressure range 0.1–400 MPa at temperatures from 303 to 573 K. The rate of pressure variations can be as low as 0.002 MPa/s over the whole pressure range. The functioning of the instrument was tested by measuring the coefficient of thermal expansivity of liquid n-hexane, with calibration performed with gaseous nitrogen and by measuring the coefficient of thermal expansivity of benzene with calibration performed with liquid n-hexane. The results are compared with literature results obtained by the piezothermal technique and with results obtained in the present instrument by the use of a pressure stepwise scanning mode. An example of an investigation of an isothermal solid-to-liquid transition in benzene is also given.

High-pressure calorimetric evaluation of ice crystal ratio formed by rapid depressurization during pressure-shift freezing of water and pork muscle

“…Using an isothermal calorimeter, Chevalier et al (2001a) measured the latent heat of water-ice mixtures that were just removed from a depressurized cell for PSF treatment, and then calculated ice fraction formed by depressurization. High-pressure (HP) calorimetry has been applied to piezo-thermal analysis of materials for several decades (Pruzan, Minassian, Figuiere, & Szwarc, 1976;Randzio, Grollier, & Quint, 1994). Some investigators have used HP calorimetry to study food materials under HP conditions either by isothermal pressure scan (P-scan) or by isobaric temperature scan (T-scan) (Le Bail, Chevalier, Chourot, & Monteau, 2001).…”

Polymer Microstructures: Modification and Characterization by Fluid Sorption

“…The use of state variables (P, V, and T) in scanning calorimetric measurements has led [2,3] from PVT calorimetry to the now well-established scanning transitiometry technique [4]. With this technique the simultaneous determination of thermal and mechanical responses of the investigated system, pertubated by a variation of an independent thermodynamic variable while the other independent variable is kept automatically constant, allows the determination of thermodynamic derivatives over extended ranges of pressure and temperature, impossible to obtain by other known techniques.…”

Advanced experimental techniques in polymer thermodynamics

“…The seminal presentation by Randzio [1] of thermodynamic fundamentals for the use of state variables (p,V,T) in scanning calorimetric measurements has opened the path [2][3][4] from p,V,T-calorimetry to the now well established scanning transitiometry technique [5]. With this technique, the simultaneous determination of thermal and mechanical responses of the investigated system, perturbated by a variation of an independent thermodynamic variable while the other independent variable is kept automatically constant, allows the determination of thermodynamic derivatives over extended ranges of pressure and temperature, impossible to obtain by other known techniques.…”