Peak exotherm temperature

DSC and DTA measurements show melting of ADN, NH4N(N02)2, at 328 K, the onset of decomposition at 421 K, and an exothermic peak at 457 K.l l Gasification of 30% of the mass of ADN occurs helow the exothermic peak temperature, and the remaining 70% decomposes after the peak temperature. The decomposition is initiated by dissociation into ammonia and hydrogen dinitramide. The hydrogen dinitramide further decomposes to ammonium nitrate and NjO. The final decomposition products in the temperature range 400-500 K are NH3, HjO, NO,... 

Fig. 5.20 The exothermic peak temperature and decomposition temperature of BAMO shift to higher values as the heating rate is increased.

The thermal properties (i.e., density, specific heat capacity, and thermal conductivity) have a particularly strong influence on the curing behavior. The exothermal peak temperature is one example It can differ significantly between a composite mold with low thermal mass and a metal mold [35], A more thorough discussion of pros and cons of different mold materials can be found in Morena [37]. 

The properties such as gel time and exotherm peak temperature, mechanical properties, that is, tensile strength and percent elongation, bond strength with... 

Thermal analysis of humic-mineral complexes has shown there is an overall reduction in the decomposition temperatures of humic acid that has been com-plexed to a mineral surface. Changes in the exothermic peak temperatures of humic substances in the free and complexed state are well-documented for synthetic mineral complexes with humic and fulvic acid (Schnitzer and Kodama, 1972 Tan, 1977 Schnitzer and Ghosh, 1982) as well as for authentic soil complexes. 

In addition to the above, the noteworthy facts observed at temperatures near 300 °C are that the first exothermic peak temperature, i.e., the finish temperature of the rapid oxidatively-heating reaction, agrees nearly with the finish temperature of the charring reaction, and, that the percentage of reduction in weight, caused by the oxidative decomposition reaction, to the quantity of the sawdust tested amounts to nearly 60 % by the time that the charring reaction finishes, etc. 

Effects of three kinds of gases, i.e., air, nitrogen gas and oxygen gas, on the individual DTA curves of the sawdust of red lauan and that of Japanese cedar are shown in Figs. 87 and 88, respectively. The figures attached to each curve denote the exothermic peak temperatures expressed each in °C. The same is true of all the DTA curves presented herein. In this connection, the pattern of the TG curve of the sawdust of every wood species, including red lauan and Japanese... 

The sawdust of red iauan has a remarkable feature that it affords three exothermic peaks in the three DTA curves recorded each in the three kinds of gases, respectively. It is clear in these three DTA curves that the value of the first exothermic peak temperature and that of the second exothermic peak temperature lower in the order of in nitrogen gas , in air and in oxygen gas , respectively. The third exothermic peaks in the three DTA curves, however, appear at temperatures near 420 irrespective of kind of gas, respectively. The latter fact may suggest that this peak does not arise on account of the surface oxidation reaction of the char, but on account of some heating reaction occurring in the interior of the char. 

Increasing the concentration of catalyst brings about a reduction in the time to the exothermic peak. The exothermic peak temperature increases as the percentage of catalyst is increased. This increase in temperature is due to the autoacceleration effect that occurs when the viscosity of the monomer-polymer solution increases very rapidly with polymer formation. The percentage of conversion is approximately constant, except for a drop at the 1.2% and 1.5% vazo... 

Figure 5. Time to exothermic peak (tp) vs. percent vazo catalyst added to basswood-MMA composite. Exothermic peak temperature and percent monomer conversion are shown on the curve.(Reproduced with permiS sion from Ref. 31. Copyright 1972, Springer-Verlag.)...

MMA monomer, which causes cross-linking to the point where the polymer will decompose before it melts. On the average, the exothermic peak temperature remains about the same as the concentration of the TMPTMA is increased from 1.0 to 20% by weight of MMA. 

The stability of the polyyne-type polymers can be examined by thermogravimetry and differential thermal analysis (TG/DTA). From the DTA curves in Figure 10.5, an exothermic peak is observed in all cases. The very broad peak for PpPE is observed around at 350°C, while the sharp peak is observed at 207°C for PpPB and at 138 C for PpPO, respectively. The exothermic peak temperature should be related with thermal stability of the polyyne-type polymers, thus it is concluded that the most stable is PpPE... 

Table I. Exotherm Peak Temperature as a Function of Particle Size.

Table 14. Comparison of the Exothermic Peak Temperature of Poly(l,6-heptadiyne) and Its Homologues...

There are numerous modified conditions of the acetic acid acetylation system practiced commercially. But the basic principles are the same. The objective in all of the commercial processes is to produce a clear, gel-free, acid dope having target viscosity. Some of the main processing factors are catalyst level, acetic acid to anhydride ratio, initial temperature of the A mix (A mix refers to a mixture of acetic acid and acetic anhydride.), amount of excess acetic anhydride, the equipment used to agitate the reaction medium, the extent of jacket cooling to control the exotherm, peak temperature (the maximum temperature reached during the acetylation), and the temperature-time profile for the acetylation. 

On cooling the heated samples, exothermic peaks, due to the crystallisation of hard segment domains, were seen in the DSC curves. Again, the higher exothermic peak temperature suggested the existence of larger size hard segments for HER elastomer. 

The effect of PE-g-MAH as compatibilizer of PE/OLS nanocomposites was investigated by varying its concentration. PE/PE-g-MAH/OLS samples showed an increase in both the exothermic peak temperature and activation energy compared with PE/OLS composites prepared with the same clay concentration, but without the compatibilizer. Hence, the clay was effective as nucleating agent and the composite system with PE-g-MAH was more active in nucleation process (Kim 2006). These effects were correlated with the increase of the melt viscosity in the case of PE/PE-g-MAH/OLS samples due to the confinement effect on the motion of the polymer chains and stronger interactions between polymer and clay. 

The non-isothermal crystallization activation energy can be derived by the combination of cooling rate and exothermic peak temperature (Tp), shown as the Kissinger method [22] in Equation (6). 

The kinetic parameters can be estimated according to Kissinger s method [27] from the dependence of the exothermal peak temperature of DSC curves on heating rate. Knowing the reaction order, the maximum point of the DSC curve, dHjdt vs T, is used to obtain the ratio E/n from the expression [28] ... 

Gpoxy conversion on the TPP concentration for the 2.00 stoichiometry. Figure (b) shows dependence of the glass transition temperature, exotherm onset temperature, and exotherm peak temperature on the TPP concentration. 

Lead metal has been shown to be important in burning-rate catalysis, where it has been proposed as the effective catalytic agent in double-base propellant combustion, in which it appears to promote the rate of collapse of organic nitrates. The lead(n) salt of 3,5-dinitro-2-pyridone and lead(ii) salts derived from >-nitrocalix[n]arene (n = 4, 6, 8) (Figure 22.1) have been prepared and shown to decrease the exothermic peak temperatures and improve the decomposition heats of the explosives NC-NG and RDX, and to increase the burning rates of both DB and RDX-CMDB propellants. ... 

The nucleation temperature is decided by obtaining the exothermal peak temperature of crystallization measured by carrying out DTA analysis on each glass that is heat treated at various temperatures in advance (Figure 2-6 (a)), and by calculating the nucleation speed from the temperature difference with the crystallization temperature of glass that is not heat treated. Below... 

Assuming the temperature to be the DTA exothermal peak temperature Tp, for a non-treated sample, ifNr= 0, and if the DTA programming rate is fast, since N/ No l with a heat treated sample, equation (2-5) can be rewritten as (2-6). 

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