Makers, users active in thermal analysis New applications open up as current instruments deliver performance and reliability to users Thermal analysis is fast becoming a more essential, and less optional, tech nique for characterizing chemical com pounds and reactions. Today's instru ments have the performance and reliability that are opening up many new applications that are paying off for research chemists. Among the dozen U.S. thermal analysis instrument makers and the thousands of users, there's much activ ity: • Instrument makers estimate that sales of all thermal analysis equipment are currently growing 30% a year and will approach $8 million this year and $15 million in 1972. • At next year's Pittsburgh Con ference, Du Pont and Perkin-Elmer will likely introduce new instruments for conducting an even wider range of thermal analysis studies. • In February of this year, Mettler C3nferred the first professional award in the field-the $1000 Mettler Award in Thermal Analysis—to Dr. Robert L. Stone at the Third Toronto Sym posium on Thermal Analysis. • In April of this year, Du Pont conducted a two-day seminar on ther mal analysis which had an unex pectedly high attendance of 155, compared to 80 at its last seminar two years ago. • Standardization agencies are just
beginning to base their testing proce dures on thermal analysis. In June 1968, the U.S. National Bureau of Standards used thermal analysis for the first time to determine the purity of o-fluorobenzoic acid as part of the compound's certificate of analysis as a standard reference material. Later in the year, the World Health Organ ization Centre for Chemical Reference Substances, in Solna, Sweden, turned to thermal analysis as a method of characterizing chemical reference com pounds. •Professional society activities in thermal analysis are moving in stride. The North American Thermal Anal ysis Society (NATAS), formed early this year, will hold its first meeting this November in Columbus, Ohio, to organize next year's programs on ther mal analysis. The International Con federation for Thermal Analysis (ICTA), formed in 1965, is working fast to standardize experimental methods around the world. • The number of research chemists' references to thermal analysis in the basic chemistry journals has been in creasing exponentially—from about 150 references in 1960 to more than 5000 in 1968. • New journals for thermal analysis are being introduced. Elsevier Pub lishing Co. will print its first issue of Thermochimica Acta in January 1970 (Dr. W. W. Wendlandt, editor-inchief, is at the University of Houston, Tex.). The Hungarian Academy of Sciences intends to publish a thermal analysis quarterly sometime next year. More significant. With this degree of professional recognition and direc tion, thermal analysis will inevitably become a more significant instrumental technique in the 1970's, as gas chroma
tography and infrared spectroscopy are today. This coming of age, though, follows a 20-year period when thermal analysis instrumentation and applica tions developed slowly and at random. Throughout the 1950's, inorganic chemists used thermal analysis to study the crystalline changes in metals and minerals as they were heated, usually to high temperatures. They built their own equipment with vacuum tube circuitry, ceramic thermocouples, furnaces, and other available parts. They seldom achieved reproducible re sults and so lost confidence in ther mal analysis as a quantitative method. Spotting a business opportunity, however, the instrument makers, par ticularly Du Pont Instruments, PerkinElmer, and Tracor's Robert L. Stone Co. division, moved quickly to de velop various thermal analysis systems, which they brought to market in 1962. They designed instruments with high sensitivity and added lower tempera ture range capability to meet the re search needs of organic chemists as well as inorganic chemists. With the introduction of such equip ment, it became apparent that in strument makers were taking two dif ferent approaches in their basic cir cuitry designs. Du Pont, Tracor, and several others introduced instruments based on differential thermal analysis (DTA) in which a sample's actual temperature change is measured (dur ing an exothermic or endothermic re action) as the sample is being heated or cooled. Perkin-Elmer, however, in troduced an instrument based on what it calls differential scanning calorimetry (DSC), in which the power required to prevent such a temperature change is measured. A point of competitive confusion
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• A gasket manufacturer uses DTA to rapidly determine the binder con tent of asbestos gasket material to en sure sufficient adhesion. • A refractory materials producer similarly uses DTA to evaluate the level of organic binders in diamond abrasive wheels. • A biologist uses DSC to find enzyme inactivation temperatures in denaturation studies. • A catalysis chemist uses DTA to determine thermal and kinetic data of various polymerization initiators. • A paint producer uses DTA and TMA to study the distortion resistance of automotive lacquers under the forces of heat and pressure. • An analytical chemist uses DSC to measure comparatively the specific heats of polymers, metals, and salts over wide temperature ranges. • Another analytical chemist uses DTA to run hazard chemical evalua tions by studying the rate of exo thermic reactions of potentially ex plosive materials. • A nitrile rubber producer uses DSC to detect glass transitions in various copolymer blends. • A polymer producer, evaluating the foaming of PVC plastisols, uses DTA to determine the effects of mon omer, accelerator, catalyst, and heat ing rates of the blowing agent. • A packaging company uses DTA to evaluate the thermal history of ex truded polyethylene film to assess its heat sealability. • A clay mining company uses DSC to quantitatively analyze kaolinite-hectorite mixtures for the con tent of each component. • Another mining company uses TGA to analyze the moisture con tents of phosphate-silicate compounds. • A food processor uses DTA to analyze the solid fat content of hydrogenated soybean oils, margarines, and shortenings. The company de veloped a correlation between DTA thermograms and the solid fat index which permits more efficient analyses than does the American Oil Chemists' Society's dilatometric method. • A n inorganic chemist is using DTA, DSC, and TMA to study the phase transitions that occur in a wide number of ammonium salts. • A polystyrene producer uses DSC to evaluate expandable bead produc tion. The company studies the tem perature and extent of heat changes that occur during the foaming proc ess and the temperature and quantity of released pentane blowing agent. • A biochemioals producer uses TGA to monitor the water content of highpurity products whose dehydration and decomposition temperatures are too close to permit conventional anal yses. AUG.
18, 1969 C&EN
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