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Thermoanalytical Instrumentation and Applications
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Kenneth S. Alexander, Alan T. Riga, Peter J. Haines
Water sorption–desorption isotherms can be carried out by using thermobalances. Newer specific instruments allow measuring water sorption–desorption isotherms at different constant temperatures and include the following [e.g., dynamic vapour sorption instrument (DVS) and Surface Measurement Systems Ltd., Monarch Beach, USA].
Effect of transient drying on mechanical properties of concrete specimens
Published in European Journal of Environmental and Civil Engineering, 2022
François Soleilhet, Farid Benboudjema, Xavier Jourdain, Fabrice Gatuingt
The sample tested came from material stored in basic water over one year. They were sawn into samples. Then they were hand-crushed resulting in a powder. This powder was sifted to remove grains with diameter above 200 μm. Finally a mass of approximately 20 mg was extracted and then resaturated for the test. The desorption tests were performed under a temperature of 25 and at a gradually decreasing hr starting at 98%. More informations on the method are available in Poyet et al. (2016). Lastly, in order to process the raw data and get rid of variability due to heterogeneity of the material, a point of the desorption isotherm ()) was calculated by a standard static method in climatic chamber with the same environmental conditions than those presented in section 2.2.1. Thus, in the case of the first campaign for instance, the raw data processing is performed accordingly to Equation (4). with wsm and wdvs the water content obtained, respectively, by static method and dynamic vapour sorption.
Influence of alkaline delignification time on the moisture uptake behaviour of hemp
Published in The Journal of The Textile Institute, 2022
Albert M. Manich, Manuel J. Lis Arias, Sonia Pérez-Rentero, Marta Riba-Moliner, Gabriela Mijas, Meritxell Martí, Diana Cayuela
Moisture absorption/desorption isotherms were performed at 25 °C on samples of approximately 10mg using a Q5000 dynamic vapour sorption DVS analyser (TA Instruments) according to the following procedure:Initial drying at 60 °C and 0% relative humidity for 300 min.Prestabilisation at 0% relative humidity and 25 °C and then, at a relative humidity RH of 5% until stabilisation was achieved.Absorption process: The sample stabilised at 5% RH was subjected to increasing absorption stages until stabilisation was reached, with RH increasing from 15% to 25%, 35%, 45%, 55%, 65%, 75%, 85% and 95%.Desorption process: Samples stabilised at 95% RH were subjected to decreasing desorption stages, with RH decreasing to 85%, 75%, 65%, 55%, 45%, 35%, 25%, 15% and 5%, to complete a cycle of moisture absorption/desorption.The maximum time that the samples remained at each absorption/desorption stage was 500 min. This time was shortened if the quasi-stabilisation conditions were reached (variation in sample mass lower than 0.01% for 18 minutes). In that case, the sample proceeds to the next stage.
EUROCORR 2020: ‘closing the gap between industry and academia in corrosion science and prediction’: part 4
Published in Corrosion Engineering, Science and Technology, 2021
L. Traverse (University of Manchester, UK) spoke on, ‘Solvent uptake, plasticisation and carbamation: the effects upon the resistance characteristics of a model epoxy amine coating.’ ‘Carbamation’ is a process that competes with the amine-epoxy reaction by the amine reacting with carbon dioxide and water, giving poor inter-coat adhesion. Epoxy amine polymer films were synthesised using Meta-xylylenediamine and bisphenol F diglycidyl ether, then exposed to water, methanol or dichloromethane. Solvent resistance was determined by differential scanning calorimetry (DSC), optical microscopy and gravimetric measurements. Destructive effects from solvent interaction were determined by comparison with an unexposed sample. In all cases, solvent interaction resulted in a lower Tg value with variable reversibility upon drying. Water diffusion was assessed by dynamic vapour sorption (DVS), showing consistent kinetics of water uptake over multiple ageing cycles; diffusion rates being more environmental humidity dependent than plasticisation. Possible carbamation of amine hardeners during polymerisation, disrupting the stoichiometry, was investigated. Environmental effects during polymerisation were identified using DVS, DSC and gravimetric uptake. Carbamation was observed by optical microscopy and IR spectroscopy. As expected, both water and CO2 were detrimental, humidity playing a greater role in deterioration than CO2 alone.