On the thermogravimetric analysis of polymers: Polyethylene oxide powder and nanofibers

Abstract

Thermogravimetric analysis of polyethylene oxide (powder and nanofibers obtained by force spinning water or chloroform solutions of polyethylene oxide) was studied using different theoretical models such as Friedman and Flynn-Wall-Ozawa. A semiempirical approach for estimating the "sigmoid activation energy" from the thermal degradation was suggested and confirmed by the experimental data on PEO powder and nanofibers' mats. The equation allowed for calculating a "sigmoid activation energy" from a single thermogram using a single heating rate without requiring any model for the actual complex set of chemical reactions involved in the thermal degradation process. For PEO (powder and nanofibers obtained from water solutions), the "sigmoid activation energy" increased as the heating rate was increased. The sigmoid activation energy for PEO mats obtained from chloroform solutions exhibited a small decrease as the heating rate was increased. Thermograms' derivatives were fitted to determine the coordinates of the inflection points. The "sigmoid activation energy" was compared to the activation energy determined from the Flynn-Wall-Ozawa model. Similarities between the thermal degradation of polyethylene oxide powder and of the nanofibers obtained from water solutions were discussed. Significant differences between the sigmoid activation energies of the mats obtained from water and chloroform solutions were reported.

Fabrication of Water‐Soluble Polythiophene/Poly (sulfonic acid diphenyl aniline)/Polyethylene Oxide Electrospun Nanofibers and Their Antioxidant Activities

“…The TGA curve of the PTh/PSDA/PEO4 electrospun nanofiber, which showed the highest antioxidant activity according to both CUPRAC and ABTS tests, was compared with that of the electrospun nanofiber of PEO polymer, which was more abundant in all nanofibers. In a study in the literature, [24] the TGAs of nanofibers obtained by rapid spinning from a solution of PEO (a molecular mass of 900 KDa) in different solvents were compared with the TGA of its powder form, and the effect of temperature was investigated. As a result, it has been reported that there is no significant (qualitative) difference in their thermal degradation, and in each case, a single sigmoid‐like dependence was noted for the temperature dependence of the (thermal) residual mass.…”

Thermal degradation of naturally aged NBR with time and temperature

“…Jiang et al [16] studied the effects of thermal aging on NBR in hydraulic oil for 70 days at 60 °C and 90 °C, finding that the Shore -A hardness value initially decreased and then increased. Although much research [17][18][19][20][21][22][23] has already been conducted on the thermal decomposition and accelerated aging of NBR, very few studies have been conducted to calculate the activation energy and pre-exponential factors to assess the life of virgin NBR and its comparison with naturally aged NBR under no-load conditions. There are various statistically reliable models; however, the fitted kinetic parameters can differ by a large magnitude, making it difficult to choose an appropriate model.…”

Assessment of micro‐scale thermal behaviors and combustion performance of organic fireproof plugging material in air atmosphere

“…[12][13][14][15] Furthermore, the kinetic parameters and reaction model can be evaluated by model-free methods and model-fitting methods, which are useful tool to analysis the thermal decomposition kinetics. [16,17] The complexity of solid material combustion is determined by the diversity of components, but it is essentially a decomposition process controlled by the thermodynamic model. [18,19] Therefore, the thermal decomposition process of multicomponent fuel can be characterized by several simple multistep reactions based on the main reaction stages.…”