(525) Weber, R. E., Peria, W. T., J. Appl. Phys., 38,4355 (1967). (526) Weinryb, E., Thesis, Univ. Paris, 1965.
(527)Weinryb, E., Fresenius 2. Anal. Chem., 243, 103 (1968). (528) Weinryb, E., Hourlier, P., Chim. Anal., 49. 219 (1966). (529) White, E. ’W., Gibbs, G. V., Am. Mineralonzst, 52, 985 (1967). (530) Ibid.; 54, 931 (1969). (531) White, E. W., Roy. R., Mat. Res. Bull., 2, 395 (1967). (532) White, E. W., White, W. B., Science, 158,915 (1967).
(533) Wilhelm, T. D., M.S. thesis, Univ. of North Dakota, Grand Forks, N. D. (1968). (534) Wise, W. N., NLCO-1014 (1968). (535) Wytaes, S. A., Philips Tech. Rev., 27.300 (1966). (536) Yakowitz, H., Heinrich, K. F. J., Metallography, 1 , 5 5 (1968). (537) Yakowitz, H., Heinrich, K. F. L., Microchim. Acta, 1 , 182 (1968). (538) Yakowita, H., Michaelis, R. E., Vieth, D. L., Advan. X-Rau Anal.,, 12.. 418 (i969). ’ (539) Yakowitz, H., iMichaelis, R. E., Veith, D. L., Nut. Bur. Std. Spec. Publ. 260-16,24 pp (1969).
(540) Yamamoto, Sachio, ANAL.CHEM., 41, 337 (1969). (541) Yamashita, &I., Watanabe, S., Jap. Analyst, 18, 143 (1969). (542) Yamagase, K., Jap. Analyst, 17, 1177 (1968). (543) Yates, G., Bramman, J. I., J . Sci. Instrum. ( J . Phys. E ) , Ser. 2, 2, 619 (1969). (544) Yin, L. I., Adler, I., Lamothe, R., Appl. Spectrosc., 23, 41 (1969). (545) Zanin, S. J., Hooser, G. E., ibid. 22, 105 (1968). (546) Ziegler, C. A., U. S. Patent 3,344,273 (1967).
Thermal Analysis C. 6. Murphy, Xerox Corporation, Rochester,
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HIS REVIEW covers the major trends in thermal analysis from the period covered by the last review (203) to October 1969. During this period, thermal analysis has made remarkable strides. A number of conferences have been devoted to the subject, including the Second International Conference on Thermal Analysis (2&), the ilmerican Chemical Society Symposium on Analytical Calorimetry (ZSq), and the Third Toronto Symposium on Thermal Analysis (179). National groups devoted to thermal analysis have been established in Japan and Italy. The Yorth American Thermal Analysis Society has been formed; i t held its first meeting a t Battelle Memorial Institute in Noveniber 1969. Among the new books, there are “Applications of Differential Thermal Analysis in Cement Chemistry” (230), “Differentialthermoanalyse” (243), and the pocket book, “La Thermo-Analyse” (110). The last has sections devoted to thermogravimetry (TGA), differential thermal analysis (DTA), evolved gas analysis (EGX), dilatometry, equilibrium diagrams, and thermometric titrations. A recent volume of the “Treatise on Analytical Chemistry” contains sections entitled “Elements of Chemical Thermodynamics: Introduction to Thermal Methods” (282), “Principles of Thermometry” (58), “Cryoscopy” (96),“Calorimetry” ( I C s ) , “Thermometric Enthalpy Titrations” (125) , and “Differential Thermal Analysis,’ (205). Reviews have appeared on DTh (80, 105, 200, 204) and derivatography (219, 271). The development of thermography in the USSR has been reviewed (23). The application of DTA and TGA to high polymers also has been the subject of a recent review (198). The Elsevier Publishing Co. has announced the publication of a new journal, Thermochimica Acta, with W. W.Wendlandt editor-in-chief. Kultura
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Press, Budapest, Hungary, has inaugurated the new journal, Journal of Thermal Analysis. Both journals will publish articles, notes, reviews, etc., in the broad field of thermal analysis. Efforts have been made, particularly by the ICTA, to establish standards for the field of thermal analysis. An initial attempt has been made (168) to establish standard nomenclature in the field. I n addition to the previously recommended method for reporting thermal analysis data (178), extensive work has been applied to and reported on the selection of standards for thermal analysis (90, 180). However, recognition for standardization of reporting procedures (269) and the need for calibration standards for DTA have been voiced by others (75, 290). DIFFERENTIAL THERMAL ANALYSIS
Dynamic scanning calorimetry (DSC) also is considered in this section. A number of equipments have been developed during the period of the review. They include apparatus for operation at high pressures (5100 kbars) and high temperatures ( S 1000’) (19), for use in vacuum and controlled atmospheres to ca. 600’ (241), for operation under hydrogen over the range of 1 to 500 bars (33),and a sensitive micro equipment for operation in vacuum or air, X2, or He, employing a disk-type differential thermocouple, with a fixed distance between the junctions, as the detector (296, 297). A simplified apparatus for examination of solid fats has been described (220). h D S C has been reported (115) in which heating and control are by focused radiation from projection lamps. The accuracy of the last equipment was determined to be 1 to 270 from runs with In, Sn, and C6H&OOH. Equipment employing vacuum-deposited Ni and Xu thermocouples (136, 137) has been de-
ANALYTICAL CHEMISTRY, VOL. 42, NO. 5 , APRIL 1970
veloped, and it has been reported that changes in heat transfer coefficient between sample and sensor have been practically eliminated, resulting in flat base lines. High precision measurements were obtained with n-C32H66and In. Equipment for single-crystal D T A has been reported (89, 235) and it has been shown (89) that such equipment can show nonreproducible effects associated with distortions, etc., which contribute to an ill-defined effect when a multitude of particles are employed. Solid-state circuitry for temperature programming, incorporating siliconcontrolled rectifiers, has been described (256) and was incorporated in hot stage microscopic equipment previously described (19 7 ) . An electrical circuit for accurate measurement of small temperature differences, incorporating thermistors, has been described (273),and D T A equipment incorporating thermistors has been used with water-salt systems (225). The significance of sample holder construction materials on thermograms has been indicated when thermal decomposition of [ (NH4)J107024. 4Hz0] was studied in P t , glass, corundum, quartz, and Ag crucibles (22). Abnormal effects were observed with P t due t o catalytic oxidation of “3. Equipment for simultaneous high temperature D T A and x-ray diffraction is available commercially (91), and such equipment with controlled atmosphere application has been described (12). Equipment for simultaneous DTA and TG.1 for application under vacuum or atmospheric pressure has been described and applied to CuS04.5H20 and cellulose (215). A simple, generalized theory for the analysis of dynamic thermal measurements has been presented (98). The influence of atmosphere on the decomposition of some metal oxalates (169) and the influence of water vapor pressure on the dehydration of CaC204.H20 (92)
have been studied. D T X has been applied to polymers in solution (141, 209). Different molecular weight fractions of polyethylene crystallized by slow cooling have shown different solution temperatures and broadened peaks have been shown to be associated with highly branched material (141). Isothermal treatment of materials, studied as a function of temperature, has been shown to be a very convenient method for elimination of overlapping peaks in polymers (196),and the DSC technique has been applied with a quenched polymer as the reference material (81) for better glass transition measurements. The electrical analog of D T A has shown that adverse shape and size effects of D T A peaks can be minimized by using small sample size, minimizing heat leakage between the samples, and effecting rapid heat transfer to the samples (291). I n a subsequent paper (190), the model was used to show that (1) the area under a D T A peak is directly proportional to heat of reaction and sample mass and inversely proportional to the thermal conductivity of the material; ( 2 ) the temperature of a D T A peak increases for increasing radius of sample and, therefore, temperature should be used as the abscissa to reduce the influence of differing sample radius; (3) the D T X peak reference temperature increases with decreasing sample conductivity and increasing specific heat and density; although peak sample temperature is sensibly independent of physical properties, they influence the peak temperature shift with heating rate, leading to erroneous values of activation energies when calculated on such a basis (140); and (4) heat loss through thermocouples results in peak area reduction and lowers the peak temperature. The applications of D S C to purity determination are increasing. The general approach has involved a graphical approach to the peak area and data substitution in a r a n ’ t Hoff expression. The technique has been applied to pharmaceuticals (63) and organic compounds (68, 223). One of the most serious limitations of the method is the assumption that no solid solutions are formed. However, an expression for treating solid solutions has been presented (68). Computer programs have been developed for simplification of calculations (68, 99). Many publications have been devoted to the application of D T l i and DSC equipment to calorimetric measurements. The mathematical problems of quantitative analysis have been discussed (24),and a simplified method for calculating the heat of phase transitions from D T A data has been presented. However, it has been pointed out that nonideal behavior would be expected to be the rule, rather than the exception in
solidl solidn transitions] with superheating, skewing, and supercooling being encountered (88). A special sample holder was used u p to 1600’ for evaluating calorimetric standards based on the melting of several metals (289), which was found to be a more reliable process than cooling. Melting of metals also was used in the statistical evaluation of such processes as the calorimetric process (245). With particle sizes ranging from
