Structural comparisons of pyrodextrins during thermal degradation process: The role of hydrochloric acid

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

Download Full-text

A thermal degradation study of Y and La methanesulfonates

Journal of the Serbian Chemical Society ◽

10.2298/jsc0609905d ◽

2006 ◽

Vol 71 (8-9) ◽

pp. 905-915

Author(s):

Moura de ◽

Jivaldo Matos ◽

Farias de

Keyword(s):

Thermal Analysis ◽

Differential Scanning Calorimetry ◽

Differential Thermal Analysis ◽

Thermal Degradation ◽

Degradation Process ◽

Oxide Formation ◽

Scanning Calorimetry ◽

Degradation Study ◽

Thermogravimetric Data ◽

Thermal Degradation Process

The synthesis, characterization and thermal degradation of yttrium and lanthanum methanesulfonates is reported. The prepared salts were characterized by elemental analysis and infrared spectroscopy. The thermal degradation study was performed using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC).Using the thermogravimetric data, a kinetic study of the dehydration ofY and Lamethanesulfonates was performed employing the Coats-Redfern and Zsak?methods. It was verified that under heating, yttrium and lanthanum methanesulfonates undergo three main processes: dehydration, thermal degradation and oxide formation. Furthermore, depending on the nature of the atmosphere, i.e., inert or oxidant, the thermal degradation process could be endothermic (N2) or exothermic (air).

Download Full-text

Thermal degradation of the anthocyanins extracts from jabuticaba peels and red cabbage leaves

Scientia Plena ◽

10.14808/sci.plena.2020.064201 ◽

2020 ◽

Vol 16 (6) ◽

Author(s):

Priscila Pereira Souza ◽

Weber Silva Robazza ◽

Alessandro Cazonatto Galvão

Keyword(s):

Thermal Degradation ◽

Degradation Kinetics ◽

Degradation Process ◽

Differential Method ◽

Red Cabbage ◽

Average Value ◽

Extraction And Purification ◽

Different Temperatures ◽

Thermal Degradation Process ◽

Experimental Values

Anthocyanins are phenolic compounds with tinctorial capacity. Their successful extraction and purification depends on information associated with their thermal stability. This work presents a study on the degradation kinetics of the anthocyanins in the peels of the jabuticaba fruits and the leaves of red cabbage through assays performed at different temperatures (ranging from 323.15 K to 363.15 K) and degradation times (up to 10 hours for jabuticaba and 30 hours for red cabbage). Total monomeric anthocyanins were determined through the pH differential method. Regarding the extraction, it was observed a larger quantity of anthocyanins from red cabbage extracts, with an average value of 1.3774 mg‧gdb-1, when compared to jabuticaba extracts, with an average value of 1.0479 mg‧gdb-1. The results suggest that the anthocyanins in the red cabbage leaves are much more thermally stable than the anthocyanins in the jabuticaba peels. The experimental assays suggest that the thermal degradation reaction proceeds according to a first-order kinetics model for the anthocyanins in both sources under study. The experimental values were treated according to their thermodynamic relations, which indicated that the thermal degradation process of the evaluated anthocyanins is endothermic and not spontaneous, with similar values of 64.8 kJ‧mol-1 for the red cabbage and 70.2 kJ‧mol-1 for the jabuticaba.

Download Full-text

Devolatilization of African Palm (Elaeis guineensis) Husk studied by TG-MS

Ingeniería e Investigación ◽

10.15446/ing.investig.v38n2.67743 ◽

2018 ◽

Vol 38 (2) ◽

pp. 9-17

Author(s):

Alberto Ricardo Albis Arrieta ◽

Ever Ortiz Muñoz ◽

Ismael Piñeres Ariza ◽

Andrés Felipe Suárez Escobar ◽

Marley Cecilia Vanegas Chamorro

Keyword(s):

Activation Energy ◽

Thermal Degradation ◽

Mass Spectroscopy ◽

Elaeis Guineensis ◽

Degradation Process ◽

Pyrolysis Process ◽

Distributed Activation Energy Model ◽

Evolved Gas ◽

Secondary Reactions ◽

Thermal Degradation Process

Using simultaneous thermogravimetrical analysis coupled with mass spectroscopy, the pyrolysis of African palm husk, using several heat rates and programs was performed. Seven relations of mass/charge were followed of the evolved gas of the pyrolysis process, fitting the kinetics and the mass spectroscopy signals to the distributed activation energy model (DAEM) with different numbers of pseudo-components. Fitting with four pseudo-components proved to be the best for modeling the thermal degradation process. Kinetic parameters were not affected by the heating rate or program employed, which agrees with other reports for similar biomass. Methane, methanol formaldehyde, furfural were successfully fitted to the DAEM model, nevertheless CO2 and NO2 were not able to be represented by this model due to its production in secondary reactions in gaseous phase.

Download Full-text