Thermal analysis experiments

The authors thank the U.S. Army Research Office for financial support of this research at TCU and SMU. The light scattering and the thermal analysis experiments were conducted, respectively, by Dr. G.L. Hagnauer (Army Materials Technology Laboratory, Watertown, MA) and Dr. J.J. Meister (SMU). 

All of the organohalogen compounds studied were commercial products obtained from various manufacturers and used as received. Only the DBDPO was purified further by recrystallization for some of the chromatography and thermal analysis experiments. Samples of antimony trioxide and antimony pentoxide were also obtained from commercial sources. The ultrapure antimony trioxide, bismuth trioxide, bismuth metal, antimony metal, dibenzofuran and diphenyl ether were all obtained from Aldrich Chemicals. The poly(propylene) (PP) resin was 0.7 mfi, food grade from Novamont and the poly(ethylene) was unstabilized, high molecular weight, HDPE from American Hoechst. 

From the results of the small scale thermal analysis experiments previously reported (23,25), it was concluded that the antimony volatilization and bromide release observed for ternary mixtures containing organobromine compounds, which did not undergo intermolecular dehydrohalogenation, could not be accounted for solely on the basis of HBr formation during degradation. 

E cooling water coil F lower electric connection G vacuum/argon connection. This scheme shows the use of the furnace for thermal analysis experiments. L differential thermal analysis head H reference thermocouple joints I thermostatic water circulation J thermocouple wires ... 

The thermal analysis experiments Involved the collection of NMR data while coal samples were being heated at 4 K/mln to 875 K under non-oxldlzlng conditions. 

Statistical analyses were applied to the M2J data from both thermal analysis experiments and measurements on coals swollen with pyridine... 

Support was provided under the National Energy Research, Development and Demonstration Program (NERDDP). T.P. Maher of the Joint Coal Board provided coal specimens and expert advice. P.J. Redllch (Monash University) supplied brown coals and extracted residues. Maceral concentrates were provided by N. Lockhart, C. Davies, M. Shlbaoka, N. Ng and A. Cook. N. Thomas and Z. Lauks performed most of the thermal analysis experiments. 

Normal safety precautions for laboratory work and for the use of electrical equipment, especially variable temperature accessories, must be observed. The thermal analysis experiment involves high temperatures and there is a danger of being burned. Consult instrument operating manual for specific cautions regarding operation. 

Potential as a Tool for Thermal Analysis of NOM. TGA typically is employed to quantify both moisture content and thermal stability of soil and sediment organic matter samples (e.g.,Tan and Hajek, 1977 and Schnitzer, 1972), including identification of structural components (e.g., Schnitzer et al., 1964). Examination of thermal stability prior to evaluation in thermal analysis experiments enables... 

The method used to provide contrast in transmission electron microscopy was successful in demonstrating the presence of a two-phase structure in homopolymer blends of BR and IR (Figure 2a). The opposite situation, i.e., a clear absence of any phase separation in the block copolymers, also is demonstrated, but much less convincingly by the comparison of Figures 2b and 2c. It is necessary to consider the evidence from all of the mechanical and thermal analysis experiments, along with the evidence from microscopy. 

Thermal analysis experiments have clearly shown that tin-based fire retardants markedly alter both the initial pyrolysis and the oxidative burn off stages that occur during polymer breakdown These changes have been interpreted as being indicative of an extensive condensed phase action for the tin additive, in which the thermal breakdown of the polymer is altered to give increased formation of a thermally stable carbonaceous char at the expense of volatile, flammable products. The consequent reduction in the amount of fuel supplied to the flame largely accounts for the beneficial smoke-suppressant properties associated with zinc stannates and other tin-based fire retardants. 

It was in 1976 that Ogata et al. reported the synthesis of inclusion polyamides [78]. When /1-cyclodextrin was stirred with aliphatic diamines in water, precipitates were formed and they were characterized as inclusion compounds. Condensation of these inclusion amides with isophthaloyl or terephthaloyl chloride yielded polyamides encircled by many of the cy-clodextrins, i.e., the first pseudopolyrotaxanes. Ogata et al. likened them to a train passing through many tunnels . The solubility and water absorption of the pseudorotaxanes were greater than those of the naked polymer threads. Differential thermal analysis experiments showed that the thermal properties of the pseudorotaxanes were different both from the naked threads and from /1-cyclodextrin. 

Microthermal analysis is a recently introduced thermoanalytical technique that combines the principles of scanning probe microscopy with thermal analysis via replacement of the probe tip with a thermistor. This allows samples to be spatially scanned in terms of both topography and thermal conductivity, whereby placing the probe on a specific region of a sample and heating, it is possible to perform localized thermal analysis experiments on those regions. 

Haines (4) has suggested a useful acronym to remember the key parameters that are important in making good general thermal analysis experiments. The author has... 

Prins et al. (21) described the lower flammability of poly-bromostyrene relative to that of polystyrene. On the basis of thermal analysis experiments, they suggested that bromine inhibited most of the oxidative chain reactions, and thus the combustion was not supported (vapor-phase mechanism). Khanna and Pearce (16) and Brauman (22) demonstrated that polystyrene could be flame retarded by appropriately modifying its structure with substituents that promote the char yield of the system (condensed-phased mechanism). 

The possible entrapment of aPP in the core of iPP spherulite was first reported by Lohse and coworkers based on small-angle neutron scattering and thermal analysis experiments (52, 53), who found that aPP and iPP are not only miscible in the melt, but also the atactic PP chains can be trapped inside the spherulites of iPP on a scale comparable to that of the crystalline lamellae. Billingham and coworkers (48) emphasized the rejection of the amorphous concentration at the growing front, but... 

However, to use thermodynamically calculated results for the interpretation requires the consideration of the materials microstructure, specific crystallization behavior and the kinetics of phase formation and phase reaction. This is true especially for the interpretation of dynamic thermal analysis experiments (e.g. DTA, TG). Moreover, heat treatments (e.g. thermolysis) are often carried out in an inert atmosphere and evaporating gaseous species are continuously removed by flowing gas atmospheres (inert or reactive). This effect deeply... 

The study of clays and minerals played an important role in the development of DTA as an investigative technique. In some instances DTA and DSC provide one of the few routes to the identification of minerals. An ingenious method, elegant in its simplicity, whereby the identity of a component in a mixture can be confirmed is to add the suspected mineral to the reference crucible and repeat the thermal analysis experiment. The relevant peaks should show a diminution in size. 

Lu Chang Zheng Yang-min (2009). Research on low-temperature oxidation and pyrolysis of coal by thermal analysis experiment. Procedia Earth and Planetary Science 718-723. 

Only a brief introduction to thermodynamics is offered in this Section. It should serve as a refresher of prior knowledge and a summary of the important aspects of the material needed frequently for thermal analysis. It is a small glimpse at what must be securely learned by the professional thermal analyst For an in-depth study, some of the textbooks listed at the end of the chapter should be used as a continual reference. This does not mean that without a detailed knowledge of thermodynamics one cannot begin to make thermal analysis experiments, but it does mean that for increasing understanding and better interpretation of the results, a progressive study of thermodynamics is necessary. 

Figure 7.3 Schematic diagram of the dynamic mechanical thermal analysis experiment (top) and a comparison of the amplitudes of the oscillation at points (1) and (2) for a semi-flexible material (bottom).

To establish a common basis for thermal analysis experiments, a series of ICTA (International Confederation for Thermal Analysis)-NBS (National Bureau of Standards) Standard Reference Materials were proposed via common experiments. These Standard Reference Materials have now been re-named ICTA Certified Reference Materials (CRM) and catalogued by the NBS (now NIST) as GM-758, GM-759 and GM-760 (see Table 1.4). The temperature standards of CRM are not the true transition temperatures of these materials, e.g. the difference between the extrapolated onset of a CRM and the equilibrium transition temperature is usually 3 "C. 

Suddenly and for unknown manufacturing reasons, many vinyl outer jackets in the assembly of an optical undersea cable system ruptured at their point of entry into an optoelectronic device during a solder reflow operation at elevated temperature. As part of an investigation into the cause of failure, several thermal analysis experiments, including DSC, DMA, and TMA, were conducted. A tensUe-mode TMA study is shown in Rg. 4.35. The cable s outer jacket (OJ) was removed. This tubular structure s outer diameter measured about 1.6mm with a wall thickness of about 0.20mm. OJ samples were cut to a length of about 23 mm and clamped between the TMA s steel clamps. A slight positive tension was maintained as the tubular sample was heated at... 

PERFORMING A MICRO/NANOSCALE THERMAL ANALYSIS EXPERIMENT... 

When DTA (differential thermal analysis) experiments had been performed open to flowing helium gas (5,6) the exothermic peaks resulting from the formation of TiH, and Cu metal were not observed, probably due to the large endothermic peak that resulted as hydrogen was released in the decomposition of the ternary hydride. 

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