Authors:E. Stepkowska, J. Perez-Rodriguez, M. Jimenez de Haro, and M. Sayagues
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.
The antihypertensive drug substance amlodipine besylate crystallizes in two stable crystal forms, an anhydrate and a hitherto
unknown monohydrate. Both forms have been characterized by thermal analysis, X-ray powder diffractometry, FTIR- and FT Raman
spectroscopy. Moisture sorption- and desorption investigations reveal their unusual physical stability in a broad range of
relative humidities. The monohydrate forms an isomorphic dehydrate upon dehydration, which was elucidated by variable temperature
X-ray powder diffractometry. Physico-chemical properties as well as relative stabilities of the crystal forms are described
and discussed based on a comprehensive analytical identification, and enable an estimation of practical relevance for manufacturing
of amlodipine besylate solid dosage forms.
Authors:M. Łaszcz, K. Trzcińska, K. Filip, A. Szyprowska, M. Mucha, and P. Krzeczyński
suggest the partial decomposition of capecitabine under influence of watersorption.
TGA curves of the initial samples KP-API2 and KP-1 and these stored for 6 months at 40 °C in 75% (RH KP-API2e and KP-1d
Authors:Yu Bolbukh, V. Tertykh, P. Klonos, and P. Pissis
with a resolution of 8 cm −1 .
Isothermal watersorption curves were recorded at room temperature by exposing the samples to water vapor atmospheres in sealed jars. Various water activities were achieved with the appropriate saturated salt
Authors:A. Kyritsis, A. Spanoudaki, C. Pandis, L. Hartmann, R. Pelster, N. Shinyashiki, J. C. Rodríguez Hernández, J. L. Gómez Ribelles, M. Monleón Pradas, and P. Pissis
sensitively on the phase morphology, which, in its turn, can be controlled by composition and preparation/processing conditions.
In previous work we employ a variety of partly complementary experimental techniques to study morphology, watersorption
Part II covers the most common methods of measuring the humidity of solid material. State of water near solid surfaces, gravimetric
measurement of material humidity, measurement of water sorption isotherms, chemical methods for determination of water content,
measurement of material humidity via the gas phase, standardisation, cosmonautical observations are reviewed.
The amorphous content of different Desferal samples was quantified by recording its recrystallization using isothermal microcalorimetry in a static as well as in a flowing humid atmosphere. Furthermore water vapor sorption gravimetry was performed for the same purpose. These analytical methods result in a quantitative signal directly dependent on the content of the amorphous phase (recrystallization, water sorption equilibrium). Their sensitivity allows the detection of amorphous content below 1%. Methods are compared and advantages and disadvantages are discussed.