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1

THERMOGRAVIMETRY OF CHITOSAN WITH NANOFILLERS

100%

Puchalska A., Mucha M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2011

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vol. 16

31 - 42

EN

In the present paper the degradation of chitosan and its blends with hydroxyapatite, nanoclay and nanosilver as well as the impact of those nanofillers added to chitosan on its decomposition at high temperatures are studied. The applied films of thickness 50 μm were obtained by casting the acidic solutions: chitosan and its blends with hydroxyapatite, nanoclay and nanosilver. To mix solutions with nanofillers ultrasounds were applied. To study the thermal degradation we applied thermogravimetry in dynamic and static conditions, which is a method of thermal analysis involving the continuous recording of weight loss Based on experimental data activation energies of thermal decomposition close to a maximum rate loss were calculated using different methods for chitosan and its blends with hydroxyapatite, nanoclay and nanosilver. The addition of three nanofillers mentioned above result in a visual increase of activation energy of thermal degradation process of chitosan due to slower evolution of decomposed gases from chitosan matrix reflected by a slower rate of weight loss.

2

Kinetic analysis of thermogravimetric data collected from bigger samples

88%

Nowicki L., Markowski M.

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vol. 33

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issue 1

85-94

EN

Results for microcrystalline cellulose pyrolysis are presented, which includes thermogravimetric measurements and kinetic analysis of experimental data. The effect of sample mass size and heating rate on estimated values of activation energy and pre-exponential factor is demonstrated and a simple modification of procedure is proposed that allows for the correct values of kinetic parameters regardless of the experimental conditions. The efficiency of the proposed method is confirmed for two endothermic chemical reactions. A method of nonlinear regression is used for calculation of kinetic parameters for a single or TG curve or several curves simultaneously.

3

Flame resistant cellulosic substrate using banana pseudostem sap

88%

Basak S., Samanta K. K., Saxena S., Chattopadhyay S. K., Narkar R., Mahangade R., Hadge G. B.

Polish Journal of Chemical Technology

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2015

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vol. 17

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issue 1

123-133

EN

Flame retardancy was imparted in cellulosic cotton textile using banana pseudostem sap (BPS), an eco-friendly natural product. The extracted sap was made alkaline and applied in pre-mordanted bleached and mercerized cotton fabrics. Flame retardant properties of both the control and the treated fabrics were analysed in terms of limiting oxygen index (LOI), horizontal and vertical flammability. Fabrics treated with the non-diluted BPS were found to have good flame retardant property with LOI of 30 compared to the control fabric with LOI of 18, i.e., an increase of 1.6 times. In the vertical flammability test, the BPS treated fabric showed flame for a few seconds and then, got extinguished. In the horizontal flammability test, the treated fabric showed no flame, but was burning only with an afterglow with a propagation rate of 7.5 mm/min, which was almost 10 times lower than that noted with the control fabric. The thermal degradation and the pyrolysis of the fabric samples were studied using a thermogravimetric analysis (TGA), and the chemical composition by FTIR, SEM and EDX, besides the pure BPS being characterized by EDX and mass spectroscopy. The fabric after the treatment was found to produce stable natural khaki colour, and there was no significant degradation in mechanical strengths. Based on the results, the mechanism of imparting flame retardancy to cellulosic textile and the formation of natural colour on it using the proposed BPS treatment have been postulated.

4

THERMAL DEGRADATION OF DOUBLE CROSSLINKED HYDROGEL CHITOSAN MEMBRANES

88%

Pieróg M., Ostrowska-Czubenko J., Gierszewska-Drużyńska M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2012

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vol. 17

71 - 78

EN

The thermal degradation behaviour of uncrosslinked and crosslinked chitosan membranes were studied by means of dynamic thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) over the temperature range 25-500ºC in nitrogen atmosphere. Modified chitosan membranes were prepared using a crosslinking method based on covalent crosslinking of chitosan with glutaraldehyde and subsequent ionic crosslinking with sodium citrate, sulfuric acid, sulfosuccinic acid and tripolyphosphate, respectively. Chemical structure of modified chitosan membranes before and after their thermal degradation was characterized by FTIR spectroscopy. Both TGA and DSC experiments as well as spectral results (FTIR spectra of thermal degradation residues) indicated some differences in the mechanism of thermal degradation of uncrosslinked and crosslinked chitosan membranes.

5

Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts

88%

Pełech I., Narkiewicz U., Kaczmarek A., Jędrzejewska A.

Polish Journal of Chemical Technology

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2014

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vol. 16

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issue 1

117-122

EN

Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described.

6

Kinetic analysis of thermogravimetric data collected from bigger samples

75%

Nowicki L., Markowski M.

Chemical and Process Engineering

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2012

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issue 1

7

Free radical formation in salicylic acid and heating parameters – application of EPR, UV-Vis, TGA and colorimetry examination to optimize thermal sterilization

75%

Ramos P., Pilawa B.

Acta Poloniae Pharmaceutica - Drug Research

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2020

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vol. 77

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issue 3

431-441

EN

Salicylic acid heated at different temperatures and times was examined by an X-band (9.3 GHz) EPR spectroscopy, UV-Vis spectrophotometry, TGA and colorimetry test to optimize its thermal sterilization process. Free radical formation (~1018 spin/g) during thermal sterilization of salicylic acid according to the pharmaceutical norms at temperature 120oC and time of 120 minutes was compared with those for heating at the new tested temperatures and times: 130oC and 60 minutes, and 140oC and 30 minutes. It was obtained that the relatively lower free radical concentrations characterized salicylic acid heated at temperatures (times): 120oC (120 minutes), and 130oC (60 minutes), than at temperature (time) 140oC (30 minutes). So treatment at temperature 120oC during 120 minutes, and temperature 130oC during 60 minutes, were recommended as the optimal for thermal sterilization of salicylic acid. Salicylic acid should not be sterilized at temperature 140oC during 30 minutes, because of the highest free radical formation. Free radical systems of thermally treated salicylic acid revealed complex character. Fast spin-lattice relaxation processes existed in heated salicylic acid. Strong dipolar interactions characterized all the heated salicylic acid samples. EPR spectroscopy, UV-Vis spectrophotometry, thermogravimetry, and color measurement may be helpful besides microbiological analysis to optimize thermal sterilization conditions of salicylic acid.

8

Reduction of Lead Oxide by Fine-Grained Carbonaceous Materials

63%

Matuła T., Siwiec G.

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issue 2

Refine search results

THERMOGRAVIMETRY OF CHITOSAN WITH NANOFILLERS

Kinetic analysis of thermogravimetric data collected from bigger samples

Flame resistant cellulosic substrate using banana pseudostem sap

THERMAL DEGRADATION OF DOUBLE CROSSLINKED HYDROGEL CHITOSAN MEMBRANES

Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts

Kinetic analysis of thermogravimetric data collected from bigger samples

Free radical formation in salicylic acid and heating parameters – application of EPR, UV-Vis, TGA and colorimetry examination to optimize thermal sterilization

Reduction of Lead Oxide by Fine-Grained Carbonaceous Materials