Adiabatic scanning calorimetry

To perform such a measurement, four methods are available adiabatic calorimetry (or adiabatic scanning calorimetry), differential scanning calorimetry (DSC), the T-history method, and in-situ measurements. These methods are described here. 

Cruz-Orea, A., Pitsi, G., Jamee, P., and Theon, J. (2002). Phase transitions in the starch-water system studied by adiabatic scanning calorimetry. /. Agric. Food Chem. 50,1335-1344. 

Fig. 12 (a) Reduced temperature T — 7]SO/bp vs xcdSe phase diagram for CE8 + CdSe mixtures obtained from cooling runs by a.c. colorimetry. Ti-bpiii was found to be a weak function of x. (b) T — rIso/BP vs xcdse plot for CE6 + CdSe mixtures obtained from heating runs by adiabatic scanning calorimetry. For clarity the data in both diagrams are plotted vs the Ti-bpiii [428]. (Copyright 2010, The American Physical Society)... 

The values of c of the ten organic liquid peroxides were measured by the adiabatic scanning calorimetry and are presented in Table 8 in Subsection 5.7.1, respectively. As noted down at the end of Section 2.4, the value of c of every chemical bears some temperature dependence. In this regard, the temperature at which the value of c of each individual organic liquid peroxide was measured is presented in parentheses after the corresponding value of c in Table 8. 

Denolf, K., van Roie, B., Glorieux, C., Thoen, Yildiz, S., and Ozbek, H. (2007) An adiabatic scanning calorimetry study of the nematic-smectic A and the nematic-isotropic phase transitions in 4-butyloxyphenyl-4 -decyloxybenzoate. Mol. Cryst. Liq. Cryst., ATJ. 3-16. 

Figure 10.15. Heat capacity of the compound FH/FH/HH-18BTMHC versus temperature, obtained by high-resolution adiabatic scanning calorimetry (from [102]).

Much of the intrinsic difficulties with DSC measurements and the tedious data collecting process of traditional adiabatic calorimetry can be avoided by adiabatic scanning calorimetry. In this technique a measured heating power is continuously applied to (or extracted from) the sample and sample holder. It was used in the 1970s for the study of liquid-gas [17] and liquid-liquid critical points [18] and first applied to liquid crystals by us [19] and later also by Anisimov et al. [20]. In the dynamic modes the total heat capacity Cj is now given by ... 

Different phase transitions involving blue phases are expected theoretically to be first-order [54] except the BPm to isotropic transition which could become second order [54] in an isolated critical point at the termination of a first-order line [6, 55], Figure 10 shows Cp results of cholesteryl non-nanoate (CN) with adiabatic scanning calorimetry [56]. From Fig. 10 it is clear that there are substantial pretransitional heat capacity effects associated with the BPm-I transition, which means that a large amount of energy is going into changing the local nematic order. The other transitions appear as small, narrow features on the BPm-I transition peak. From the inspection of the en-... 

Table 8-1. Latent Heats measured in pure 8CB by different techniques. A comparison of latent heats (error bars in parentheses) from Intensity fluctuation microscopy (IFM latent heats are estimated from the measured (/q = I.2 0.I) x 10 [66] and Landau parameters in [65]), Adiabatic Scanning Calorimetry (ASC errors from [69]) and Modulated differential scanning calorimetry (MDSC errors estimated from smaller error bar). Also listed is the molar fraction X of lOCB in 8CB-10CB (alkyl-cyanobiphenyl) mixtures at which the latent heat appears to vanish...

Experimental measurements of zero (or non-zero) latent heat should always be coupled with an estimate for experimental resolution (see Table 8-1). A recent adiabatic scanning calorimetry ( ASC ) study [69] reiterates the results of an older study [58] and puts an upper bound on the NA transition in 8CB at < 2 J/kg. In the presence of relatively large impurity concentrations ( 5 mole % of cyclohexane in 8CB) ASC does measure a discontinuity of 17 J/kg [70] (here the estimated errors are 5 J/kg). Ibe stated errors in the MDSC data are large ( 11 J/kg as estimated from the smallest error bar on the graph) and thus consistent with both the intensity fluctuation microscopy (IFM) results of Yethiraj et al and the ASC... 

Differential scanning calorimetry (DSC) can be performed in heat compensating calorimeters (as the adiabatic calorimetry), and heat-exchanging calorimeters (Hemminger, 1989 Speyer, 1994 Brown, 1998). 

Differential scanning calorimetry (DSC) is a thermal method that measures the energy change accompanying a non-adiabatic process. A small sample of the... 

Stephens and Roth (2) measured enthalpy (350-1191 K) by drop calorimetry and heat capacity (298-785 K) by differential scanning calorimetry. We fit the 14 enthalpy points at 400-812 K with a polynomial, using the adiabatic (1 ) and DSC (2) data as a... 

Nanophase materials generally have an excess heat capacity and entropy relative to the bulk. These can be obtained by conventional heat capacity measurements (adiabatic calorimetry, differential scanning calorimetry), although problems with the adsorbed water and other gases are more severe for nanomaterials than for bulk phases. Data at present are fragmentary and it is difficult to evaluate their accuracy. Dugdale et al. (1954) report on excess heat capacity for fine grained rutile. Victor (1962) report data for MgO and BeO, and Sorai et al. (1969) for Ni(OH)2 and Co(OH)2. 

Thermodynamic data from solution calorimetry using molten lead borate [95, 101] for the perovskite and garnet phases have been combined with data for the YAM phase, and heat capacity data from adiabatic calorimetry and differential scanning calorimetry have been used to calculate the phase diagram for the binary system. This recent study shows unequivocally congruent melting of the perovskite phase and that it does not decompose to the YAM phase + liquid [95],... 

The specific heat of ZrP207(cr) was measured by Warhus et al. [88WAR/MAI] using both adiabatic and differential scanning calorimetry between 1.2 and 800 K. The authors found that the specific heat could be described by the following equation ... 

Sodium zirconium triphosphate, NaZr2P30 2, is one of the end members of the NASICON solid solution system (Nai+vZr2SivP3-jtO 2(s) (0thermochemical data determined for this species by Maier et al. [86MAI/WAR], between 1.5 and 810 K using a combination of adiabatic and differential scanning calorimetry, are discussed in Section V.7.2.5. The selected thermochemical data are ... 

Warhus et al. [88WAR/MAI] measured the specific heat of Na2ZrSi207(s) from 100 to 800 K using adiabatic and differential scanning calorimetry. Values calculated by [88WAR/MA1] for the thermochemical properties are as given below ... 

Worswick et al. [74WOR/COW] reported low-temperature (adiabatic calorimetry) heat capacity measurements (10 to 300 K) and differential scanning calorimetry (DSC) results from 300 to 550 K. The equation (V.66) (200 to 550 K) is not in the standard form generally used for solids e.g., [93KUB/ALC], p. 166, Equation (116)), however, the original DSC data are unavailable. 

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