Final Decomposition Temperature Research Articles

Thermoanalytical investigation of the formation of RuO 2-based mixed-oxide electrodes

The processes of formation of RuO 2 TiO 2 coatings from precursor salts dissolved in isopropanol were followed by combined thermoanalytical and mass-spectrometric methods. The electrochemical characterization of the coatings was carried out by cyclic voltammetry. The pyrolysis of the titanium precursor salt, titanium diisopropoxide bis-2,4-pentanedionate, consists of four stages and involves the formation of elemental carbon in the coating. The steps of solvent desorption, oxidative cracking and combustion could be detected by comparison of the curves obtained. In the case of the pyrolysis of ruthenium and titanium salt mixtures, owing to the catalytic effect of the noble metal addition, the final decomposition temperature was reduced by more than 100 °C. In the main combustion step an almost complete conversion of the organic matter to CO 2 and H 2O takes place. The highest rate of decomposition and of heat release is observed for a coating composition between 10 and 30 mol% of Ru. Cyclic voltammetry experiments showed that the maximum charge-storage capacity, as indicated by larger surface areas, is also observed in this composition range.

X-ray CT apparatus: 43283 Mori, I.; U.S. Patent No. 4,858 129 (15 Aug. 1989)

A novel graft copolymer of vinyltriethoxysilane onto ethylene propylene diene terpolymer has been developed by grafting varying contents of VTES using dicumyl peroxide as an initiator in a twin-screw extruder. Grafting of VTES and EPDM has been ascertained using FTIR. The EPDM-g-VTES developed has been blended with different weight percentage of linear low density polyethylene [LLDPE] by melt mixing. Thermal, thermal ageing and morphological behaviour of the blends are studied with respect to the effect of blend composition, static vulcanization and dynamic vulcanization with varying quantities of VTES and LLDPE. The incorporation of silane moiety onto EPDM raises the inception and final decomposition temperature. The stability EPDM-g-VTES/LLDPE blend increases with increase in concentration of EPDM-g-VTES due to thermally stable Si–O–Si linkage. It was ascertain from SEM micrograph that EPDM-g-VTES/LLDPE blends lead to formation of interpenetrating crosslinked network during hot water treatment and by treatment with DCP, respectively. The linear, statically vulcanized, dynamically vulcanized and filled blends of EPDM-g-VTES/LLDPE have been characterized to assess the suitability of the blends for high performance applications. In addition, it is also observed that the incorporation of fillers improves thermal stability of the blends.

Computed tomography inspection of electronic devices: 43004 Armistead, R.A. U.S. Patent No. 4,852,131 (25 Jul. 1989)

A novel graft copolymer of vinyltriethoxysilane onto ethylene propylene diene terpolymer has been developed by grafting varying contents of VTES using dicumyl peroxide as an initiator in a twin-screw extruder. Grafting of VTES and EPDM has been ascertained using FTIR. The EPDM-g-VTES developed has been blended with different weight percentage of linear low density polyethylene [LLDPE] by melt mixing. Thermal, thermal ageing and morphological behaviour of the blends are studied with respect to the effect of blend composition, static vulcanization and dynamic vulcanization with varying quantities of VTES and LLDPE. The incorporation of silane moiety onto EPDM raises the inception and final decomposition temperature. The stability EPDM-g-VTES/LLDPE blend increases with increase in concentration of EPDM-g-VTES due to thermally stable Si–O–Si linkage. It was ascertain from SEM micrograph that EPDM-g-VTES/LLDPE blends lead to formation of interpenetrating crosslinked network during hot water treatment and by treatment with DCP, respectively. The linear, statically vulcanized, dynamically vulcanized and filled blends of EPDM-g-VTES/LLDPE have been characterized to assess the suitability of the blends for high performance applications. In addition, it is also observed that the incorporation of fillers improves thermal stability of the blends.

Reconstructive computer-aided tomography in dynamic-process research (review): 42462 Altukhov, A.A.; Gusev, E.A.; Dzhikaev, Y.K. Soviet Journal of Nondestructive Testing, Vol. 25, No. 1, pp. 1–10 (Sep. 1989)

A novel graft copolymer of vinyltriethoxysilane onto ethylene propylene diene terpolymer has been developed by grafting varying contents of VTES using dicumyl peroxide as an initiator in a twin-screw extruder. Grafting of VTES and EPDM has been ascertained using FTIR. The EPDM-g-VTES developed has been blended with different weight percentage of linear low density polyethylene [LLDPE] by melt mixing. Thermal, thermal ageing and morphological behaviour of the blends are studied with respect to the effect of blend composition, static vulcanization and dynamic vulcanization with varying quantities of VTES and LLDPE. The incorporation of silane moiety onto EPDM raises the inception and final decomposition temperature. The stability EPDM-g-VTES/LLDPE blend increases with increase in concentration of EPDM-g-VTES due to thermally stable Si–O–Si linkage. It was ascertain from SEM micrograph that EPDM-g-VTES/LLDPE blends lead to formation of interpenetrating crosslinked network during hot water treatment and by treatment with DCP, respectively. The linear, statically vulcanized, dynamically vulcanized and filled blends of EPDM-g-VTES/LLDPE have been characterized to assess the suitability of the blends for high performance applications. In addition, it is also observed that the incorporation of fillers improves thermal stability of the blends.

Mössbauer studies of polyethyl methacrylate containing ferric chloride as a stabilizer

Polyethyl methacrylate /PEMA/ containing ferric chloride was prepared by free radical polymerization at 70°C. Mossbauer studies of the polymer heated at 150°C, 300°C and 500°C for 1 h showed that during the thermal degradation the Fe3+ species are reduced to Fe2+ and the final form is α-Fe2O3. TGA studies showed that the addition of ferric chloride during the polymerization of ethyl methacrylate increased the thermal stability of PEMA by 40°C. The final decomposition temperature /FDT/ increased by 75°C.

Thermoplastic matrix composites by aqueous electrocopolymerization onto graphite fibers

AbstractElectrocopolymerization of 3‐carboxyphenyl maleimide and styrene onto Hercules AS‐4 graphite fiber surfaces has been successfully carried out from an aqueous solution containing monomers and dilute sulfuric acid. Initiation of copolymerization of the monomers dissolved in a small amount of dimethylacetamide is achieved by constant‐current electrolysis in the cathodic chamber of a three‐compartment electrolysis cell. Polymerization is initiated at the fiber surfaces; little polymer is formed in the cell solution. Electrocopolymerization is very consistent and rapid. The amount of polymer increases predictably with increasing comonomer concentration and current density. Using a 0.4 M (1 : 1) comonomer concentration, 0.0125 M sulfuric acid solution, and a current density of 20 mA/g, more than 60 wt % of copolymer coating per unit weight of graphite fibers is obtained within thirty minutes. Thermal gravimetric analysis showed the copolymer to be very stable at elevated temperatures and has initial and final decomposition temperatures of 430 and 520°C, respectively. The glass transition temperature measurement of the copolymer coatings was carried out by differential scanning calorimetry. A single glass transition temperature was obtained of about 210°C for most samples. The glass transition temperature of the copolymers did not change significantly with changing comonomer feed composition. Functional group and compositional analysis of the copolymer was done by FTIR spectroscopy. The copolymer composition remained relatively the same for copolymers made from different styrene/3‐carboxyphenyl maleimide feed composition, confirming a strong tendency toward alternation for the system.

Radiation decomposition of metal acetyl acetonates

Studies on the thermal decomposition of the acetyl acetonate complexes of transitional metal ions Cu/II/, Cr/III/, Mn/II/, Co/II/, Fe/III/, Vo/II/, Zn/II/, and Cd/II/ have been performed by thermogravimetric method. Taking the initial decomposition temperature as a measure of thermal stability, the relative order of the thermal stability of these complexes shows the following order: Zn/II/<Cd/II/< VO/II/<Fe/III/<Cr/III/<Cu/II/≅Co/II/< Mn/II/. The nature of decomposition of Cu/II/ and Cr/III/ complexes is similar, a sigmoid curve exists. In other cases a long linear decomposition follows the sigmoid pattern. The linear decomposition is a function of final decomposition temperature and percentage of decomposition. The kinetics of the decomposition is analyzed according to the Coats-Redfern equation. The results are discussed on the basis of structural and other aspects leading to the decomposition.

Effects of nickel(II) oxide on the thermal decomposition of alkali persulfates

The thermal decomposition of Na 2S 2O 8 and K 2S 2O 8 has been studied derivatographically in the presence of NiO at various molar mixtures. Experiments have proved that the first decomposition stage (persulfate into pyrosulfate) is independent of the amount of the oxide present. During the second decomposition stage (pyrosulfate into sulfate) which occurs in the melt, NiO plays the role of lowering the melting, the initial and final decomposition temperatures of pyrosulfates. The lowest melting temperatures recorded for Na 2S 2O 8 and K 2S 2O 8 are 320 and 280°C, respectively. A mechanism has been proposed to describe the catalytic action of NiO on the thermal decomposition of alkali pyrosulfates. The mechanism makes use of the semiconductivity of NiO and the availability of electron-rich centers in the pyrosulfate group to help the formation of an adsorption complex between them. NiO reacts to some extent with alkali pyrosulfates forming the yellow NiSO 4 and alkali sulfates as separate products. NiO and NiSO 4 form eutectic mixtures with alkali sulfates melting at temperatures lower than those of the pure salts.

The effect of CO 2 pressure and alkali salt on the mechanism of decomposition of dolomite

A detailed investigation of the mechanism of decomposition of dolomite in a specially designed thermal apparatus has been performed. Results show that much of the published thermal analysis data for dolomite represent decomposition at some unknown but high CO 2 pressure. Detailed results confirm that CO 2 pressure affects both the initial decomposition temperature into MgO and CaCO 3 and the final decomposition temperature of CaCO 3, but in opposite directions. This demonstrates the existence of different decomposition mechanisms. Alkali salt also affects the decomposition temperature regardless of the gaseous atmosphere, and in some instances may cause decomposition to occur by a completely different mechanism.

A contribution to the use of hydrazinium (+2) fluoride as fluorinating agent

The use of hydrazinium(+2) fluoride as fluorinating agent was investigated in the N 2H 6F 2Al system. Ammonium fluoroaluminates have been isolated and characterised as intermediate products, formed during the thermal treatment, required, to remove the excess of hydrazinium(+2) fluoride. The general conclusion proposed is, that the final thermal decomposition temperature required, if hydrazinium(+2) fluoride is used as a fluorinating agent in the synthesis of binary metal fluorides, depends on the thermal stability of their ammonium fluorometalates. The thermal decomposition of hydrazinium fluorometalates is discussed.

Thermogravimetric analysis: temperature limits and rate of heating

In the case of the decomposition of carbonates and hydrates, the Polanyi-Wigner equation often applies. A mathematical expression relating the temperature at a given stage of the reaction to the rate of decomposition, fraction of reactant left, initial weight and area of the compound and finally the rate of heating has been derived from the above equation. For a given thermobalance the minimum detectable rate of decomposition and fraction of reactant left are fixed so that the observed final decomposition temperature is a function of the rate of heating for a constant weight and area of material. Using this equation, values for the final decomposition temperatures have been calculated and compared with data found in the literature for the decomposition of calcium carbonate and for the dehydration of potassium chrome alum and orthoboric acid. The equation also has been applied to the dehydration of 5-nitrobarbituric acid trihydrate as determined by us.