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of the phenol adsorption enthalpies are less frequent [ 2 , 10 – 13 ]. In this respect, mainly flow adsorption and/or titration calorimetry are valuable techniques to gain reliable data [ 10 , 12 ], giving evidently exothermic effects in all known
Introduction Temperature-modulated differential scanning calorimetry (TMDSC) developed by Reading et al. [ 1 ] was commercialized shortly afterward and is being widely applied in different fields such as material research
describe the interaction of GlyGly with copper(II) ions and to gain knowledge of the mechanism of formation of a biologically relevant complex, calorimetric measurements were conducted. Isothermal titration calorimetry and potentiometric measurements were
structure and thermal behavior including plasticization, gelatinization, and retrogradation is crucial. Differential scanning calorimetry (DSC) and hot-stage polarized optical microscopy are methods of choice for studying starch gelatinization. The
magnitude of the undercooling during solidification can also be measured [ 13 ]. Differential scanning calorimetry (DSC) is a powerful technique that measures the enthalpy change of a sample under controlled conditions, e.g. in solidification or phase
Abstract
Reaction calorimetry strongly penetrated process development laboratories in the fine chemicals industry. Applications of calorimetry to different fields of process optimization, chemical reactions and physical unit operations were developed. Applications were first developed in the field of process safety. The thermal data of reaction obtained in the calorimeters allow us to check if a reaction will be controllable at full scale under normal operating conditions and in case of equipment failure. Further, the accurate temperature control and heat flow measurement opened the door to more engineering related data, in the fields of phase equilibria like vapour liquid, solubilities, crystallization and also in the mixing techniques. Some examples of developments in these different fields will be reviewed.
Calorimetry in the studies of cement hydration
Setting and hardening of Portland cement–calcium aluminate cement mixtures
Abstract
Calorimetry was applied to an investigation of the early hydration of Portland cement (PC)–calcium aluminate cement (CAC) pastes. The heat evolution measurements were related to the strength tests on small cylindrical samples and standard mortar bars. Different heat-evolution profiles were observed, depending on the calcium aluminate cement/Portland cement ratio. The significant modification of Portland cement heat evolution profile within a few hours after mixing with water was observed generally in pastes containing up to 25% CAC. On the other hand the CAC hydration acceleration effect was also obtained with the 10% and 20% addition of Portland cement. As one could expect the compressive and flexural strength development was more or less changed—reduced in the presence of larger amount of the second component in the mixture, presumably because of the internal cracks generated by expansive calcium sulfoaluminate formation.
Abstract
Initial plant scale trials of the nitrosation of an amino acid revealed a number of issues: _ Much lower yield compared to laboratory scale _ Considerable loss of mass balance _ Large excess of nitrosating agent required for complete reaction _ Highly reactive off-gases produced causing fires in the carbon absorber _ Reaction sensitive to agitation speed _ The by-product produces an impurity in the next process stage which has high human toxicity A kinetic and mechanistic study of the nitrosation reaction, using isothermal power compensation calorimetry and GC/mass spectrometry, has been undertaken in order to understand the above observations and to produce an improved manufacturing process - more robust, higher yielding, reduced effluent volumes and toxicity.
A thermodynamic analysis of the uniaxial stretching of polyurethanes of various compositions and mechanical histories was carried out by using deformation calorimetry. The initial small strain deformations were found to result from the volume elasticity of the hard phase. The intramolecular energy contributions of the soft blocks were estimated. The hard block contributions were shown to depend on their content and on the degree of sample stretching. The predominant role of the soft component is proved to be manifested only in softened samples with a hard block content not exceeding 30%. The thermodynamics of the softening and hysteresis phenomena were studied. The dependence of the deformation mechanism on the hard block content and mechanical history is discussed.
