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Titanium(IV)–EDTA complex

Kinetics of thermal decomposition by non-isothermal procedures

Journal of Thermal Analysis and Calorimetry
Authors: Luciana Guinesi, C. Ribeiro, Marisa Crespi, A. Santos, and Marisa Capela

Abstract  

This work aims the evaluation of the kinetic triplets corresponding to the two successive steps of thermal decomposition of Ti(IV)–ethylenediaminetetraacetate complex. Applying the isoconversional Wall–Flynn–Ozawa method on the DSC curves, average activation energy: E=172.49.7 and 205.312.8 kJ mol–1, and pre-exponential factor: logA=16.380.84 and 18.961.21 min–1 at 95% confidence interval could be obtained, regarding the partial formation of anhydride and subsequent thermal decomposition of uncoordinated carboxylate groups, respectively. From E and logA values, Dollimore and Mlek methods could be applied suggesting PT (Prout–Tompkins) and R3 (contracting volume) as the kinetic model to the partial formation of anhydride and thermal decomposition of the carboxylate groups, respectively.

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Abstract  

The recycling of soft drink bottles poly(ethylene terephthalate) (PET) has been used as an additive in varnish containing alkyd resin. The PET, called to recycled PET (PET-R), was added to the varnish in increasing amounts. Samples of varnish containing PET-R (VPET-R) were used as a film onto slides and its thermal properties were evaluated using thermogravimetry (TG). Throughout the visual analysis and thermal behavior of VPET-R it is possible to identify that the maximum amount of PET-R added to the varnish without changing in the film properties was 2%. The kinetic parameters, such as activation energy (E) and the pre-exponential factor (A) were calculated by the isoconversional Flynn-Wall-Ozawa method for the samples containing 0.5 to 2.0% PET-R. A decrease in the values of E was verified for lower amounts of PET-R for the thermal decomposition reaction. A kinetic compensation effect (KCE) represented by the lnA=−13.42+0.23E equation was observed for all samples. The most suitable kinetic model to describe this decomposition process is the autocatalytic Šesták-Berggren, being the model applied to heterogeneous systems.

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Abstract  

Samples of water based commercial acrylic resin paints were spread in a film form on slides, dried at room temperature and exposed to solar radiation for up to eight months. The characterization and quantification of resins and charges in the white paint emulsion were carried out for the thermal decomposition. Besides this, X-ray diffractometry was used to identify CaCO3 as charge and TiO2 (rutile phase) as pigment. It was observed through thermal techniques similar behavior to the samples even though with varied exposure time. Kinetic studies of the samples allowed to obtain the activation energy (E a) and Arrhenius parameters (A) to the thermal decomposition of acrylic resin to three different commercial emulsion (called P1, P2, P3) through non-isothermal procedures. The values of E a varied regarding the exposition time (eight months) and solar radiation from 173 to 197 kJ mol−1 (P1 sample), from 175 to 226 kJ mol−1 (P2 sample) and 206 to 197 kJ mol−1 (P3 sample). Kinetic Compensation Effect (KCE) observed for samples P2 and P3 indicate acrylic resin s present in these may be similar in nature. This aspect could be observed by a small difference in the thermal behavior of the TG curves from P1 to P2 and P3 sample. The simulated kinetic model to all the samples was the autocatalytic Šesták-Berggreen.

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Abstract  

Bagasse samples from four different sugarcane were directly collected as the residues of milling in a processing plant. The samples were dried at 105 °C, compressed to small granules and then their TG/DTA and DSC curves in synthetic air were recorded. Similar thermogravimetric curves were obtained for the different samples and they exhibited four mass loss steps. However, the analysis of the exotherm DSC peaks showed that the oxidation of the organic matter resulted different enthalpy values (ΔH/kJ g−1).

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Abstract  

Poly(3-hydroxybutyrate), PHB has been structurally modified through reaction with maleic anhydride, MA. Transesterification reaction was carried out fixing the PHB and MA and besides time and temperature the concentration of the triethylamine (used as catalyst) was changed. Glass transition, melting and crystallization temperature obtained from DSC curves and thermal degradation temperatures obtained from TG traces were used to evaluate the influence of the reaction conditions on the modification of PHB according to factorial design. On the base of the results the optimum conditions are to perform the PHB modification reaction with MA reaction at 110C for 1 h with 5% v/v triethylamine.

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Abstract  

Leachate samples from a sanitary landfill of Araraquara city and composting usine of Vila Leopoldina, São Paulo, Brazil were lyophilized to remove the water content. TG/DTG curves at different heating rates were recorded. The second step of the thermal decomposition of leachate from the Araraquara landfill (CB1), from the composting usine from Vila Leopoldina (CB2) from the organic phase extracted (FO) and aqueous phase (FA) were all kinetically evaluated using the non-isothermal method. By Flynn-Wall isoconversional method the following values were obtained: E=234±3.65 kJ mol−1 and logA=29.7±0.58 min−1 for CB1; E=129±1.66 kJ mol−1 and logA=11.8±0.10 min−1 for CB2; E=51.6±1.35 kJ mol−1 and logA=6.09±0.09 min−1 for FO and E=76.91±6.33 kJ mol−1 and logA=8.88±0.7 min−1 for FA with 95% confidence level. Applying the procedures of Málek and Koga, SB kinetic model (Šesták-Berggren) is the most appropriate to describe the decomposition of CB1, CB2, FO and FA.

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Abstract  

The number of the cities with canalized water and sewage treatment stations has increased lately and consequently having in mind the great concern on environment preservation and the quality of the water used by society. However, these stations are nowadays causing another kind of problem: a huge quantity of sludge as residue. Due to the implication of the residue on the environment and, consequently, to human life quality, performing of an accurate investigation about the components of such sludge, as well as the thermal stability of this residue in the environment become necessary. This paper presents a study on sludge from water and sewage treatment station, as well as the thermal characterization of residue. Such study was performed through FTIR, atomic absorption, thermoanalytical (TG/DTG, DTA) techniques, that made it possible to observe that the main components of the sludge are clay, carbonates and organic substance, presenting a low rate of metals and a unique thermal behavior since the sludge from the treatment station has a higher thermal stability.

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Abstract  

PHB [poly (3-hydroxybutyrate)], post-consumer soft-drink bottles poly (ethylene terephthalate) PET (herein named PET-R) and PHBPET-R (blends of PHB and PET-R in several compositions) samples were evaluated by differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM) in order to verify their thermal properties and porosity according to amounts of PET-R added the blends. The DSC curve showed that the solvents used to solve the polymer mixture cause changes in the thermal behavior of PET-R films and in PHBPET-R blends. SEM studies of the PHBPET-R blends show that with a gradual mass increase of PET-R, there are gradual increases in the porosity of the films.

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Abstract

Meglumine, (2R,3R,4R,5S)-6-methylaminohexane-1,2,3,4,5-pentol, is a carbohydrate derived from sorbitol in which the hydroxyl group in position one is replaced by a methylamine group. It forms binary adducts with substances having carboxyl groups, which have in common the presence of hydrogen bonding as the main force in the stabilization of these species. During melting, adducts of meglumine with flunixin (2-[[2-methyl-3-(trifluoromethyl)phenyl]amino]pyridine-3-carboxylic acid) polymerize or self-assemble in amorphous supramolecular structures with molecular weights around 2.0 × 105 kDa. DSC curves, in a first heating, show isomorphic transitions where the last one at 137 °C for the flunixin-meglumine adduct originated the supramolecular amorphous polymers with glass transition around 49.5 °C. The kinetic parameters for the thermal decomposition step of the polymers were determined by the Capela-Ribeiro non-linear isoconversional method. From data for the TG curves in nitrogen atmosphere and heating rates of 5, 10, 15, and 20 °C min−1, the E α and B α terms could be determined and, consequently, the pre-exponential factor, Aα, as well as the kinetic model, g(α).

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Journal of Thermal Analysis and Calorimetry
Authors: Marcelo Kobelnik, Douglas Lopes Cassimiro, Adélia Emilia de Almeida, Clóvis Augusto Ribeiro, and Marisa Spirandeli Crespi

Abstract

The Al and In-diclofenac compounds were prepared. Thermogravimetry (TG) and X-ray diffraction powder patterns were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic studies of these stages were evaluated from several heating rates with mass sample of 2 and 5 mg in open crucibles under nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data leads to a dependence on the sample mass, which results in two kinetic behavior patterns.

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