Weight loss upon heating

In our studies, the model substance (montmorillonite) was a calcium bentonite (Istenmezeje, Hungary), the characteristic features of which are given here. X-ray diffraction (intensity of the basal reflection) and thermoanalytical (weight loss upon heating) data show 91% montmorillonite content. The other constituents are 5% calcite, 3% kaolinite, 1% x-ray amorphous silicates, and a trace of quartz. The amorphous phase is silicate particles, which are not crystalline for... 

TGA data taken on a prebaked but unsintered piece of Er Ba Cu O shows that a majority of the weight loss upon heating occurs above0750 C. Some of the weight loss can be attributed to the liberation of CO in spite of the previous prebaking steps. However... 

Polyacrylate superahsorhent powders — Estimation of the moisture content as weight loss upon heating NWSP 230.0.R2 (15) ISO 17190-4 2001. 

This ajqnxjadi, using 1,4,5,8-naphthakne tetracarbox ic acid and 3,3 diamino benzidine, has yielded a step-ladder structure, which can be spun to a fiber from sulfuric add solution and which undergoes no weight loss upon heating to 600 C in Ng 102—105). 

In summary, the presumption from thermal curing data is that heating above 165 °C results in sulfur-sulfur bond rupture and weight loss. Since the degradation is not quantitative, the residual thiosulfate functionality renders the "cured" films somewhat water sensitive, resulting in swelling and weakening of the polymer upon exposure to water. 

Kim etal. (1998) investigated the effect of different treatment times and temperatures upon the decay resistance of wood thermally modified in air against T. palustris. The relationship between heating period and weight loss due to decay was modelled using a regression equation. Improvements in decay resistance were found as the heating period and temperature increased. Erom the numerical analysis employed, it was predicted that heat treatment at 150 °C for about 150 hours would achieve decay resistance comparable to that of a CCA treatment at 1 % retention. 

The results obtained are consistent with the existing views on the tendency of polyconjugated systems towards spontaneous stabilization upon thermal treatment heating makes the system more resistant to thermal degradation. TGA curves (Fig. 4.2) of the samples subjected to thermal treatment at 200 and 350°C are shifted to higher temperatures, with retention of the general pattern of weight loss. Thus, the carbon-rich structures were formed at relatively low temperatures. 

The high thermal stability of zeolites and related micro-porous solids is one of their most attractive features. Whilst it Is clear that materials with organic components cannot withstand ultra-high temperatures, quite respectable compositional stability can be achieved. Thus the [Er(TMA)] polymer mentioned above shows no weight loss in its TGA curve before 550°C. However for porous solids another key issue is that of structural stability. Many open framework coordination polymers lose their crystalline structure upon mild heating, or even evacuation, through loss of guest molecules. 

It is interesting that similar low-temperature weight loss peaks on the DTG curves were also observed for lamellar silicates templated by CTMA+, but the overall shape of the DTG curves was somewhat different [22]. It is not fully clear why these lamellar materials exhibited surfactant decomposition at such low temperatures. This behavior may be related to either properties of their silicate surface or the structural changes in their framework upon heat treatment, or both of these factors, which would promote the Hoffmann elimination at lower temperature [22]. The second of these possible factors may be related to the stress in... 

Ward showed that the maximum hydroxyl group intensity was reached at 350°C and remained constant to 500°C. (148). As the temperature was raised above 500°C, the 3650- and 3550-cm-1 bands decreased until at 800°C, very few hydroxyl groups were observed on the surface. The loss of hydroxyl group absorption intensity upon heating above 500°C was accompanied by marked weight loss of the sample. This phenomenon was attributed to the loss of water by dehydroxylation by a mechanism resulting in formation of tricoordinated aluminum atoms (Lewis acid sites) and tricoordinated silicon atoms (146), as represented by structure I. This... 

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