Programmed cooling

Fig. 15 Cooling curves of crystallinity (solid line) and demixing parameter of comonomers (dashed line). The latter is defined as the mean fraction of neighboring sites occupied by other comonomers around each comonomer. The cooling program is a stepwise increase of Ep/(k T) from zero with a step length of 0.002 and a step period of 300 Monte Carlo cycles, a The slightly alternating copolymer with a comonomer mole fraction 0.36 b the heterogeneous copolymer with a comonomer mole fraction of 0.36 [52]...

Fig. 22 Cooling curves of the disorder parameter for 32-mers in 32-sized cubic lattice with a conventional cooling program (dashed line) and an optimized cooling program (solid line). Polymers have a volume fraction of 0.0625 with B/Ec = 0 and Ep/Ec = 1 [14]...

The two temperatures shown in Table III, for example, 350°C. - 150°C. means the autoclave is initially heated to 350°C. and is then uniformly cooled to 150°C. within the time given in column 6. In Table IV, the fifth column lists the temperature, for example, 450 430°C., which indicate that the autoclave is heated to 450°C. at the lower end (charge zone) and 430°C. at the upper end, and is kept under these conditions for the time given in column 6. After being heated in this manner, the autoclave is cooled to room temperature. In some cases a cooling program follows the heat treatment. 

Semiinfinite Extent. The conservation equations are subject to the boundary conditions implied by equilibrium at the solid-liquid interface with a specified cooling program and a semiinfinite extent of the liquid (l [D t]V2). The concentration of the liquid solution is assumed to be uniform initially. The growth rate, v, and thickness, d, are determined by mass conservation at the moving boundary ... 

In order to obtain a complete separation of the different compounds, a two level heating and cooling program has been established in the oven zone, coupled with column isolation. Runtime of the chromatographic method is 23.4 minutes. The flame ionisation detector (FID) is used to analyse hydrocarbons (CH4 and C3H ). The thermal conductivity detector (TCD) is used to analyse H2. CO. CO2, N2 and high concentration of hydrocarbons (CH4 and C3Hg). The polarity and sensitivity of the thermal conductivity detector have been set according to (he conductivity response of the... 

Figure 1. Cooling programs for crystal growth by slow cooling I, constant linear growth rate II, constant cooling rate III, optimum allowing for decrease in maximum stable growth rate as crystal becomes larger. (From Ref 1.)...

Thus, when a suitable cooling program is adopted, close temperature control and stirring by means of smooth changes in crucible rotation rate can give large... 

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After having reached room temperature the ampoules are cut open and the reaction products further treated. The products obtained (of which three main types can be distinguished) are found to be highly dependent on the cooling program. 

It is the provision of dynamic conditions in which the sample is subjected to a controlled heating or cooling program which sets DSC apart from other calorimetric techniques and is a key factor in its wide... 

On an industrial scale, the maximum cooling rate is often limited by the heat-transfer capacity of the equipment, which means that the theoretical cooling program cannot be followed during the final stage of the batch. A high suspension density may cause high secondary nucleation and, thus, decrease the crystal size of the product. 

Stir bar has to be removed, introduced into a glass tube, and transferred to thermal desorption instrument. After desorption and cryofocusing within a cooled programmed temperature vaporization (PTV) injector, the volatiles were transferred onto the analytical GC column. Comparison of SPME and the above-mentioned stir bar sorptive extraction (SBSE) technique using identical phases for both techniques exhibited striking differences in the recoveries, which has been attributed to ca. 100 times higher phase ratio in SBSE than in SPME. A comprehensive treatment of SBSE, discussion of the principle, the extraction procedure, and numerous applications was recently been published by David and Sandra (2007). 

This method is applicable owing to the low thermal inertia of the calorimeter and the stability of the emulsion. Nevertheless, when the cooling programmed temperature is reached at time ti the sample continues to crystallize. To avoid this perturbation, the sample is rapidly heated to temperature T s and then melted more slowly. 

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