Authors:H. Halttunen, M. Hurtta, I. Pitkänen, and J. Nurmi
Summary Anhydrous lactitols (A1, α- and β-lactitol), lactitol monohydrate, lactitol dihydrate and lactitol trihydrate were kept for varying times in atmospheres of different relative humidity at 20°C in equivalent size plastic desiccators. The relative humidities (8-95%) were maintained with saturated salt solutions and drying agents (silica gel and phosphorous pentoxide). The composition of the samples was monitored by thermogravimetry, differential scanning calorimetry and X-ray powder diffraction. According to these measurements both lactitol monohydrate and lactitol dihydrate were substantially stable under the conditions used. Lactitol monohydrate converts to lactitol dihydrate at the highest relative humidity used. All phases of anhydrous lactitol convert into a form of lactitol monohydrate but not to lactitol dihydrate, even at the highest relative humidity used. At a high relative humidity lactitol trihydrate easily loses part of its crystal water and converts partly to lactitol dihydrate. At a lower relative humidity, the phase forming from trihydrate is difficult to identify.
Authors:I. Pitkänen, J. Huttunen, H. Halttunen, and R. Vesterinen
FTIR spectrometry combined with TG provides information regarding mass changes in a sample and permits qualitative identification
of the gases evolved during thermal degradation. Various fuels were studied: coal, peat, wood chips, bark, reed canary grass
and municipal solid waste. The gases evolved in a TG analyser were transferred to the FTIR via a heated teflon line. The spectra
and thermoanalytical curves indicated that the major gases evolved were carbon dioxide and water, while there were many minor
gases, e.g. carbon monoxide, methane, ethane, methanol, ethanol, formic acid, acetic acid and formaldehyde. Separate evolved
gas spectra also revealed the release of ammonia from biomasses and peat. Sulphur dioxide and nitric oxide were found in some
cases. The evolution of the minor gases and water parallelled the first step in the TG curve. Solid fuels dried at 100C mainly
lost water and a little ammonia.
Authors:J. Suuronen, I. Pitkänen, H. Halttunen, and R. Moilanen
The thermochemical behaviour of betaine and betaine monohydrate was investigated under two degradation conditions. Betaine was heated up to 700°C at 10°C min–1 in air and nitrogen flows and the evolved gas was analysed with the combined TG-FTRIR system. The evolved gas from betaine pyrolysis at 350 and 400°C was analysed by gas chromatography using mass-selective detection (Py-GC/MSD). In addition, the electron impact mass spectra of betaine and betaine monohydrate were measured.Esterification is one of the most important pyrolytic processes involving beta- ines. Even glycine betaine can change to dimethylglycine methyl ester via intermolecular transalkylation by heating. Trimethylamine, CO2, and glycine esters were the main degradation products. Small amounts of ester type compounds evolved both in pyrolysis and with TG-FTIR. The monohydrate lost water between 35 and 260°C while the main decomposition took place at 245-360°C. The residual carbon burnt in air to CO2 up to a temperature 570°C.