scholarly journals Thermal and structural characterization of the vitreous samples in the SiO2 - PbO - Na2O system

2006 ◽  
pp. 89-95 ◽  
Author(s):  
Catalina Mocioiu ◽  
Georgeta Jitianu ◽  
Maria Zaharescu

Lead-containing glasses have been used from the ancient time. Recently, due to the possible application in optics, electronics, nuclear techniques, wastes inactivation. the interest in these types of glasses has been renewed. For lead waste inactivation, glasses with high amount of PbO in the composition are required, those exhibiting at the same time a high chemical and thermal stability. Thermal behavior of lead-silicate glasses was examined by differential thermal analysis (DTA). Infrared spectroscopy was used to investigate the structure of the glasses. The spectra were interpreted in terms of the structures of silicate group by comparison with the spectra of other silicate crystals. The DTA and infrared data were correlated with the chemical stability tests.

2018 ◽  
Vol 39 (4) ◽  
pp. 21
Author(s):  
Gilbert Bannach ◽  
Rafael R. Almeida ◽  
Luis G. Lacerda ◽  
Egon Schnitzler ◽  
Massao Ionashiro

Several papers have been described on the thermal stability of the sweetener, C12H19Cl3O8 (Sucralose). Nevertheless no study using thermoanalytical techniques was found in the literature. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) and infrared spectroscopy, have been used to study the thermal stability and thermal decomposition of sweetener.


2005 ◽  
Vol 30 (1) ◽  
pp. 15-20 ◽  
Author(s):  
E. C. Rodrigues ◽  
A. C. Vallejo ◽  
E.Y. Ionashiro ◽  
G. Bannach ◽  
M. Ionashiro

Solid state M-L compounds, where M stands for bivalent Mn, Ni, Cu and L is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry - differential thermal analysis (TG-DTA), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds.


e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Jun-Li Ren ◽  
Feng Peng ◽  
Run-Cang Sun ◽  
Xun-Li Zhang

AbstractThe reaction of hemicelluloses, isolated from wheat straw, with acrylamide in alkaline aqueous solution was investigated. The degree of substitution (DS, up to 0.65) of the products could be obtained by adjusting the molar ratios of reagent to xylose unit in hemicelluloses (1.0-10.0) and the molar ratios of catalyst to xylose unit in hemicelluloses (0.5-1.6). Changes in the structure of hemicelluloses were verified by FT-IR and 1H and 13C NMR spectroscopies. The results showed that carbamoylethyl groups surely were grafted onto the main chain of hemicelluloses. Moreover, it was also found that the saponification of carbamoylethyl groups to carboxyl groups occurred in alkaline medium. The behavior of modified hemicelluloses was monitored by means of thermo gravimetry (TG) and differential thermal analysis (TGA). It was found that the products had a lower thermal stability than the native hemicelluloses.


2011 ◽  
Vol 295-297 ◽  
pp. 64-69
Author(s):  
Xin Wen Peng ◽  
Jun Li Ren ◽  
Lin Xin Zhong ◽  
Feng Peng ◽  
Run Cang Sun

Hemicellulose isolated fromDmMwas converted to novel functional biopolymers by maleylation using maleic anhydride as reactant and LiOH as catalyst. The reaction was performed under various temperatures, times, and the amounts of catalyst and maleic anhydride on the degree substitution (DS) of products were discussed. Comparison of the reaction in different media was discussed in detail. The product had the maximum degree of substitution (DS) of 0.75. Novel functional polymers containing with carbon-carbon double bond and carboxyl groups could be confirmed by13C NMR spectroscopy. The behavior of novel hemicellulosic derivatives was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA). It was found that the products with a high DS had a lower thermal stability than the native hemicelluloses.


2005 ◽  
Vol 30 (2) ◽  
pp. 25-30
Author(s):  
R.A. Mendes ◽  
G. Bannach ◽  
E.Y. Ionashiro ◽  
M. Ionashiro

Solid state compounds of 4-methylbenzylidenepyruvate with Al(III), Ga(III), In(III) and Sc(III) have been synthesized. Complexometry, X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA) have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and thermal decomposition of these compounds.


2003 ◽  
Vol 28 (1) ◽  
pp. 19-24
Author(s):  
G. Bannach ◽  
E. Schnitzler ◽  
M. Ionashiro

Solid state compounds M-2-Cl-BP, where 2-Cl-BP is 2-chlorobenzylidenepyruvate and M represents Al, Ga, In, and Sc were prepared. X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA), have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and thermal decomposition of the compounds.


Molbank ◽  
10.3390/m1101 ◽  
2019 ◽  
Vol 2020 (1) ◽  
pp. M1101
Author(s):  
Richa Mardianingrum ◽  
Susanti ◽  
Ruswanto Ruswanto

The bis(N′-(3-chlorobenzoyl)isonicotinohydrazide)iron(III) complex was synthesised from N′-(3-chlorobenzoyl)isonicotinohydrazide and iron(III) metal by reflux in an ethanol solution. The title compound was characterised by Fourier-transform infrared spectroscopy (FTIR) spectroscopy, differential thermal analysis/thermogravimetric analysis (DTA/TGA) and UV-visible spectroscopy. The results indicate that coordination of the iron(III) ion to the ligand increased its thermal stability.


Calphad ◽  
2021 ◽  
Vol 73 ◽  
pp. 102258
Author(s):  
František Zelenka ◽  
Jakub Strádal ◽  
Pavel Brož ◽  
Jan Vřešťál ◽  
Jiří Buršík ◽  
...  

2014 ◽  
Vol 805 ◽  
pp. 486-491
Author(s):  
J.M.R. Figueirêdo ◽  
Juliana Melo Cartaxo ◽  
I.A. Silva ◽  
C.D. Silva ◽  
Gelmires Araújo Neves ◽  
...  

The State of Paraíba, Brazil, retains about 88.5% of all Brazilian bentonite, and much of this production comes from deposits in the District of Boa Vista, PB. Nevertheless, the deposits are almost depleted. Recently, new deposits were found, which will increases the reserves of the State, in the regions of Cubati and Pedra Lavrada, PB. The objective of this work is to characterize and develop purified clays, through sieving and hydrocycloning techniques, from those recently discovered bentonites for several applications. The characterization of the sample was done through granulometric analysis by laser diffraction, X-ray diffraction, chemical analysis by X-ray fluorescence, and thermogravimetric and differential thermal analysis. The results show that the samples are typical of bentonite clays, and that the purification solely by hydrocyclone presents the best results.


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