Quantitative determination of specific heat by differential scanning calorimetry

Abstract

The influence of some experimental parameters on the quantitative determination of specific heats by DSC is discussed. Conditions allowing measurement of the specific heat with a maximum relative error of 1.5 ~ are proposed. The specific heats of NaA zeolite, Cp -----0.227 __+ 0.003 cal.~ -1, and AgA zeolite Cp = 0.205 __+ 0.003 cal.~ -1 have been determined.Specific heat can be relatively simply determined by DSC. Scanning of an external standard (usually synthetic sapphire) and a sample is accompanied by the corresponding deflections from the base line. Taking into account the correction due to blank deflection amplitude, the amplitude to mass ratio yields the value of the specific heat Cp of the sample directly.A (sample) M (sapphire) Cp (sample) = A (sapphire) M (sample) 9 Cp (sapphire)Equation (1) is based upon the proportionality between the amplitude and mass values and includes no other parameters, either internal or external. However, as it has been pointed out [1][2][3] that in DTA analysis peak area is not a linear function of mass, it can be expected that (1) is not generally valid. With our measurements, the specific heat could not be determined by means of Eq. (1) with an error of less than 10 ~ when working with the generally proposed "reasonable" limit of 40 rag.In this paper, the effects of different parameters on the determination of Cp by DSC are examined in a similar way as was done by Berg and Egunov [4] for the heat of phase transitions in DTA. ExperimentalA Perkin-Elmer DSC-1B was used for C D determination. An aluminium sample pan of 5.7 mm diameter and average weight 26 mg was put into the holder, and heated uniformly from the lower side. The temperature of the holder was measured with a platinum resistance thermometer. The sample was put into the sample pan, which was closed; it was always subjected to the same pressure. By this means,

DSC study of the effect of irradiation upon the glass transition temperature (T g) of polyethylene

“…Recently, a considerable number of publications have appeared which involve the use of the DSC for the determination of the specific heats of different polymers [6][7][8][9][10]. Stehling and Mandelkern [11 ] determined the Tg of linear polyethylene by DSC experiments.…”

Thermodynamic and thermokinetic characterization of vitreous eutectic germanium-tellurium alloy by differential scanning calorimetry

“…Results so obtained can, moreover, be improved by using the methods developed by Richardson [6], Vucelic [7] or Flynn [8]. However, in a large temperature range this method implies some restrictions in the matter of the alignment of the base lines before and after the heating period; these cannot easily be satisfied, and they restrict its field of application [5].…”

Determining thermal physical properties of pyrolyzing New Zealand medium density fibreboard (MDF)

“…This may be a reasonable assumption due to the fact that MDF is a wood based product; however, measuring the specific heat experimentally would either support or refute this assumption. In this case, differential scanning calorimetry (DSC), which is regarded as an effective way of measuring specific heats of different materials (Vucelic et al, 1973;Park et al, 2009), is used to measure the specific heat of MDF.…”