Thermogravimetric analysis after

In most of the studies discussed above, except for the meta-linked diamines, when the aromatic content (dianhydride and diamine chain extender), of the copolymers were increased above a certain level, the materials became insoluble and infusible 153, i79, lsi) solution to this problem with minimum sacrifice in the thermal properties of the products has been the synthesis of siloxane-amide-imides183). In this approach pyromellitic acid chloride has been utilized instead of PMDA or BTDA and the copolymers were synthesized in two steps. The first step, which involved the formation of (siloxane-amide-amic acid) intermediate was conducted at low temperatures (0-25 °C) in THF/DMAC solution. After purification of this intermediate thin films were cast on stainless steel or glass plates and imidization was obtained in high temperature ovens between 100 and 300 °C following a similar procedure that was discussed for siloxane-imide copolymers. Copolymers obtained showed good solubility in various polar solvents. DSC studies indicated the formation of two-phase morphologies. Thermogravimetric analysis showed that the thermal stability of these siloxane-amide-imide systems were comparable to those of siloxane-imide copolymers 183>. 

Poly(N-phenyl-3,4-dimethylenepyrroline) had a higher melting point than poly(N-phenyl-3,4-dimethylenepyrrole) (171° vs 130°C). However, the oxidized polymer showed a better heat stability in the thermogravimetric analysis. This may be attributed to the aromatic pyrrole ring structures present in the oxidized polymer, because the oxidized polymer was thermodynamically more stable than the original polymer. Poly(N-phenyl-3,4-dimethylenepyrroline) behaved as a polyelectrolyte in formic acid and had an intrinsic viscosity of 0.157 (dL/g) whereas, poly(N-pheny1-3,4-dimethylenepyrrole) behaved as a polyelectrolyte in DMF and had an intrinsic viscosity of 0.099 (dL/g). No common solvent for these two polymers could be found, therefore, a comparison of the viscosities before and after the oxidation was not possible. 

TGA. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are other means to confirm the above structural models. Figure 4.4.8 shows the thermal analysis data for sample I. Curve (a) shows a TG datum of a mass loss about 22% after heating over 350°C. The derivative curve (b) of mass loss curve (a) clearly shows that there are at least four steps during the decomposition of the sample. This finding was further confirmed by the DTA data curve (c) shown in the same figure. It is clearly seen that there are four endothermic peaks. The DTA and TGA curves were similar for all samples. Note that the relative ratios of mass... 

Amount of deposited material - Table 4 shows the deposited weight measured with thermogravimetric analysis (TGA) for the different carbon black types after polyacetylene deposition at 27 Pa monomer pressure, 250 W power, and 1 h treatment time. These values show that the most active carbon black is the fullerene soot EP-P434. 

Transparent yellow iron oxide has the a-FeO(OH) (goethite) structure on heating it is converted into transparent red iron oxide with the a-Fe203 (hematite) structure. Differential thermogravimetric analysis shows a weight loss at 275 °C. Orange hues develop after brief thermal treatment of yellow iron oxide and can also be obtained by blending directly the yellow and red iron oxide powders. 

Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were performed simultaneously, using DTG-50 (Shimadzu), on the HMS samples after SFE. The mass loss between 150 to 300°C can be attributed to the decomposition and combustion of the amine template [3]. Hence, by expressing the mass loss of the samples in this temperature range as a percentage of the mass loss of the as-synthesised sample in the same temperature range, the extraction efficiency can be determined. 

A saturated solution of C70 (190 mg) in benzene (150 mL) was prepared and hydrogenated following the same procedure detailed in the previous Section 7.2.2. Immediately after the hydrogenation the solution was distilled under reduced pressure in a water bath at 50°C. The cream-white residue was collected for the FT-IR and thermogravimetric analysis. 

The reaction product was isolated by distillation under reduced pressure as a white powder and employed immediately after the synthesis in the registration of the FT-IR spectrum and in the thermogravimetric analysis. 

The [Cr(H20)(0H) 0P(C H8)20 2]a polymer is a green solid which is readily soluble in chloroform, benzene, and tetrahydro-furan but is insoluble in water and diethyl ether. It does not melt before decomposing thermogravimetric analysis indicates decomposition starting at 365°C. A freshly prepared solution in chloroform has an intrinsic viscosity ranging from 0.03 to 0.04 dl./g. The intrinsic viscosity increases slowly when solutions in organic solvents (for example, 1 g./lOO ml. in chloroform) are allowed to stand at temperatures of approximately 55°C., and values of 0.6-0.8 dl./g. are common after a number of days. A sample with an intrinsic viscosity of 0.04 dl./g. 

Thermal Analysis. Thermogravimetric analysis of I—V reveals that they are stable up to temperatures of 50, 150, 150, 280, and 350 °C, respectively, after which time they... 

ThermoGravimetric Analysis (TGA) was performed on TGAQ50 (TA Instruments) under air up to 800°C. FTIR spectra were obtained on a Spectrum One from Perkin Elmer Instruments. Elemental Analysis was performed by Service Central d Analyse from CNRS located at Vemaison (France). Con-ductimetry back-titration of amine functions (after contact with HCL 0.1 N in excess) was performed using a Tacussel conductimetry probe by a 0.1M NaOH solution. Porosimetry measurements were performed on a SORPTOMATIC 1990 from CE Instruments specific surface areas were calculated using BET model between P/P =0 and P/P =0.4 and pore size repartitions were determined using BJH model. SEM photos were obtained on an Ultra 55 (Zeiss). 

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