A new method of obtaining the kinetic parameters from thermogravimetric curves has been proposed. The method is simple and applicable to reactions which can not be analyzed by other methods. The effect of the heating rate on thermogravimetric curves has been elucidated, and the master curve of the experimental curves at different heating rates has been derived. The applications of the method to the pyrolyses of calcium oxalate and nylon 6 have been shown ; the results are in good agreement with the reported values. The applicability of the method to other types of thermal analyses has been discussed, and the method of the conversion of the data to other conditions of temperature change has been suggested. From these discussions, the definition of the thermal stability of materials has been criticized.

A New Method of Analyzing Thermogravimetric Data

A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter-comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass-reinforced CTL 91-LD phenolic resin, where the rate law - (1/we)(dw/dt) = 1018e−55,000/RT [(w - wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.

Kinetics of thermal degradation of char-forming plastics from thermogravimetry. Application to a phenolic plastic

/pdf/the-surface-chemistry-of-amorphous-silica-zhuravlev-model-4kfs2lx66q.pdf

The surface chemistry of amorphous silica. Zhuravlev model

A New Analysis of Thermogravimetric Traces.

Mechanistic implications of plastic degradation

The nonisothermal method of Freeman and Carroll is used to investigate the kinetics of the thermal degradation of polyethylene and polystyrene. The reactions were studied thermogravimetrically under a vacuum of 1 mm Hg. Decomposition appears to occur in stages. The rate parameters were determined for each region of reaction. Mechanisms of degradation are suggested. The results of this investigation are compared with the kinetic parameters reported by other investigators for the decompostion of these polymers.

The kinetics of the thermal degradation of polystyrene and polyethylene

La structure de la phase isotrope L 3 observee dans les systemes agent de surface-eau ou agents de surface-eau-huile est analysee. Cette etude est appliquee au cas des agents de surface non ioniques

Isotropic bicontinuous solutions in surfactant-Solvent systems: the L3 phase

The kinetics of the thermal decomposition of the polyester, Laminac 4116, were investigated in air and argon at atmospheric pressure by means of a continuous recording thermobalance and by differential thermal analysis. Samples were heated from ambient temperature to 600°C. at rates of 5°/min. and 15°/min. In air and argon, decompostion commences at 200°C. and is complete at 550 and 450°C., respectively. Four modes of degradation in oxygen and two in argon are indicated from derivative plots of the thermogravimetric curves. The kinetics of reaction were evaluated by the method of Freeman and Carroll. In the presence of air, the initial stage of reaction appears to involve formation of an unstable hydroperoxide intermediate which undergoes rearrangement and degradation. The energy of activation was calculated to be 19 kcal./mole. An exotherm corresponding to this first stage of degradation is observed by differential thermal analysis. The second and third stages of reaction in air correspond approximately to the two stages in argon with respect to their endothermal nature and to the temperature regions over which they occur. Mass spectrometric and infrared analysis were employed for identification of gaseous and volatile products. The fourth stage of reaction in air appears to involve the oxidation of carbon to carbon dioxide. Mechanisms of reaction are proposed and discussed.

The kinetics of the thermal degradation of the synthetic styrenated polyester, laminac 4116

Effects of Radiation and Doping on the Catalytic Activity of Magnesium Oxide on the Thermal Decomposition of Potassium Perchlorate

The effect of exposure of ammonium perchlorate to x and radiation on its chemical reactivity with respect to thermal decomposition was investigated. The course of the reaction was followed by differential thermal analysis and by thermogravimetric experiments conducted under ambient and reduced pressures. Decomposition was also studied by microscopic observations. The data show that several stages of reaction are involved in the decomposition of ammonium perchlorate and that the low temperature stages are appreciably enhanced as a result of preirradiation. The relative importance of the various stages of reaction were found to be a function of the exposure dose. Although direct evidence is lacking, it is suggested that the increased reactivity of the irradiated substance may be due to the presence of positive holes which would favor an electron transfer mechanism of decomposition. The effect of impurities such as Ag/sup +/, Cu/sup ++/, and I- ions on decomposition seem to support the suggested mechanism. The decomposition pattern of samples exposed to rays is similar to that of the x-ray irradiated ammonium perchlorate. (auth)

David A. Anderson

Papers

The kinetics of the thermal degradation of polystyrene and polyethylene

Isotropic bicontinuous solutions in surfactant-Solvent systems: the L3 phase

The kinetics of the thermal degradation of the synthetic styrenated polyester, laminac 4116

Effects of Radiation and Doping on the Catalytic Activity of Magnesium Oxide on the Thermal Decomposition of Potassium Perchlorate

The effects of x-ray and gamma ray irradiation on the thermal1 decomposition of ammonium perchlorate in the solid state