Exothermal effects

Copper naphthenate added to the resin at levels between 100—200 ppm effectively extends gel and cure characteristics, resulting in a reduction in exothermic heat (Eig. 7). Copper additives are used widely in commercial laminating resins to modify process exothermic effects. a-Methylstyrene [98-83-9] substituted for styrene at levels of 5—8% has also been used effectively in resins cured at above ambient temperatures. The inhibitor 2,5-di-/-butyIhydroquinone exerts significant exotherm suppression at levels of 200—400 ppm and is useful in high temperature mol ding processes. 

In given work the possibilities enumerated above of varieties of thermal analysis used to reseai ch of solid solutions of hydrated diphosphates with diverse composition. So, for example, the results of differential-thermal analysis Zn Co j P O -SH O showed, that it steady in the time of heating on air to 333 K. A further rise of temperature in interval 333 - 725 K is accompanied with the masses loss, which takes place in two basic stages, registered on crooked TG by two clear degrees, attendant to removal 4,0 and 1,0 mole H O. On crooked DTA these stages dehydration registers by two endothermic effects. In interval 603 - 725 K on crooked DTA is observed an exothermal effect. 

Balabanov et al. [499] found an endothermic effect in the thermographic pattern of the decomposition of niobium hydroxide at 435°C that corresponds to complete removal of water. At the above temperature, amorphous niobium hydroxide also converts into amorphous niobium oxide. Ciystallization of the amorphous oxide occurs at a higher temperature with the release of energy [28]. Researchers [499] reported on another exothermal effect at 549°C that was attributed to the crystallization temperature of amorphous niobium oxide. Decomposition of tantalum hydroxide and its conversion into crystalline tantalum oxide occurs at about 710°C [502] or at 670-700°C according to another source [132]. 

The concentration of K2TaF7 in the initial melt is the main parameter controlling the particle size and surface area of the reduced primary powder [598]. Typically, the increased concentration of K2TaF7 leads to the formation of coarse tantalum powder. According to Yoon et al. [599], the diluent prevents a strong increase in the temperature of the melt that is caused due to the exothermic effect of the reduction process. Based on the investigation of the reduction process in a K2TaF7 - KC1 - KF system, it was shown that increased amounts of diluent lead to a decrease in particle size of the obtained tantalum powder. 

The authors of [99] proposed a calorimetric method for determining the degree of the polymer-filler interaction the exothermal effect manifests itself in the high energy of the polymer-filler adhesion, the endothermal effect is indicative of a poor, if any, adhesion. The method was used to assess the strength of the PVC-Aerosil interaction with Aerosil surface subjected to different pre-treatments... 

C. Thermal degradation of polyazines of this type occurs with marked exothermal effects, accompanied by a practically complete evolution of nitrogen as N2 from the polymer. 

The cationization of the monomer proceeds, according to Eq. (20), as an exothermic process (proton affinity of ethene) and without any activation. The great exothermic effect and the small space need of a free proton are responsible for the latter fact. 

Fig. 8.8 Thermal effects on the formation of La3(B3N6) by metathesis reaction from equimolar amounts of LaCl3 and Li3(BN2). The strong exothermic effect in the heating curve (solid line) between 550 and 575 °C...

A mixture erupted vigorously one horn after preparation [1], Interaction (not vigorous) of amines and halocarbons at ambient temperature had been recorded previously [2], The presence of 5 basic centres in the viscous amine would be expected to enhance exothermic effects. 

An attempted thermite reaction with aluminium powder and copper(II) oxide in place of iron(III) oxide caused a violent explosion. An anonymous comment suggests that a greater reaction rate and exothermic effect were involved, and adds that attempted use of silver oxide would be even more violent [1]. An explosion... 

A cyclohexane scream is recycled to the feed and also performs an important function. It acts as a heat sink or a sponge, diluting the exothermic effect of the hydrogenation reaction, keeping the temperature down. Ac temperatures about 450°F, the decomposition of benzene to those Ugh ends just mentioned increases rapidly. 

What does exothermic effect of hydrogenation reaction mean ... 

Figure 3.30 shows the DSC traces for the (MgH + 20, 30, 50 and 70 wt%LiAlH ) composites. Only single endothermic peak centered at 350°C is visible in DSC traces for the (MgH + 20 wt%LiAlH ) composite (Fig. 3.30a). This peak corresponds to the decomposition of MgH. The first low temperature exothermic effect observed in Fig. 3.9 for a pure LiAlH (both unmilled and milled), which is usually assigned to the interaction of LiAlH with hydroxyl impurities [67], is not observed in Fig. 3.30a-c but it appears in Fig. 3.30d for (MgH + 70 wt%LiAlH ). Four endothermic events occur for (MgH + 30, 50 and 70 wt%LiAlH ) (Fig. 3.30b-d). The first endothermic peak at 174-182°C has almost exactly the same temperature range as (Rla) in Fig. 3.9. No exothermic peak (Rib) of melting from Fig. 3.9 is seen in Fig. 3.30a-d. It seems that the addition of just 30 wt%MgH suppresses melting of LiAlH and its first decomposition into LijAlH and Al ((Rib) in Fig. 3.9) occurs from a solid phase and is endothermic. This is supported by the observation of partial decomposition of LiAlH into (LijAlH + Al) during milling as discussed before. The second endo peak in Fig. 3.30b-d at 198,193 and 223°C, respectively, corresponds to the decomposition...

The carbon dioxide anion-radical usually plays the role of a one-electron reductant in DMF its E° = -1.97 V (Amatore and Saveant 1981). In the gas phase, solitary C02 loses one electron with an exothermic effect of ca. 45 kJ moC (Compton et al. 1975). 

Differential thermoanalysis involves recording the temperature difference between an inert compound and the sample during heating. Such differences occur if reactions take place which either release (exothermic effect) or consume (endothermic effect) energy. These effects are recorded as peaks on a plot of the temperature difference versus the temperature. Such thermal effects are associated with the loss of adsorbed H2O and structural OH as in TGA and also with phase transformations. 

Figure 4.21 shows the sensor output for the smart automated sensor expert system-controlled run. The resin reached the center sensor at 37 min. The viscosity is maintained at a low value by permitting slow increases in the temperature. At 60 min, fabric impregnation was complete. The resin was advanced during a 121 °C hold to a predetermined value of degree of cure of 0.35, based on the Loos model s predictions of the extent of the exothermic effect. This value of a is clearly dependent on panel thickness. Then at 130 min, the ramp to 177°C was begun. Achievement of an acceptable complete degree of cure was determined by the sensor at 190 min. Then the cure process was shut down. 

The reaction instantaneously generates a release of energy and an increase of temperature. Very quickly, when adding 5 mL of water or Diphoterine , this exothermic effect decreases, because of dilution, and the temperature returns to 20°C. 

Org. Synth. Coll. Vol. 4 124. Freshly distilled butyl glyoxylate reacts with the diene with exothermic effect. 

Mixtures of methyl methacrylate and methacrylic acid or butyl methacrylate are also used. Polymer-monomer mixtures are often used in the production process. This allows reduction of the total exothermic effect of the process, shrinkage, and production time. These mixtures are obtained by two methods ... 

Analysis of the non-isothermal polymerization of E-caprolactam is based on the equations for isothermal polymerization discussed above. At the same time, it is also important to estimate the effect of non-isothermal phenomena on polymerization, because in any real situation, it is impossible to avoid exothermal effects. First of all, let us estimate what temperature increase can be expected and how it influences the kinetics of reaction. It is reasonable to assume that the reaction proceeds under adiabatic conditions as is true for many large articles produced by chemical processing. The total energy produced in transforming e-caprolactam into polyamide-6 is well known. According to the experimental data of many authors, it is close to 125 -130 J/cm3. If the reaction takes place under adiabatic conditions, the result is an increase in temperature of up to 50 - 52°C this is the maximum possible temperature increase Tmax- In order to estimate the kinetic effect of this increase... 

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