Adiabatic vacuum calorimetry

The temperature dependences of heat capacity of the same full seq-IPNs in the 6-340 K range were studied [50] using adiabatic vacuum calorimetry. Using a calorimeter equipped with a static bomb and an isothermal shell, the energies of combustion of the CPU and of the... 

The kinetics were studied by adiabatic calorimetry [18] and high vacuum isothermal dilatometry [21, 22]. The calorimeter and the dilatometers were fitted with electrodes [21] for measuring the conductivity of the reaction mixtures. 

There are a number of different types of adiabatic calorimeters. Dewar calorimetry is one of the simplest calorimetric techniques. Although simple, it produces accurate data on the rate and quantity of heat evolved in an essentially adiabatic process. Dewar calorimeters use a vacuum-jacketed vessel. The apparatus is readily adaptable to simulate plant configurations. They are useful for investigating isothermal semi-batch and batch reactions, and they can be used to study ... 

Calorimetry. Polymer samples were ground in a Wiley mill, screened through a 100-mesh sieve, and vacuum dried at 35° C. for 15-20 hours. The samples were then pressed into cylindrical V2 X 3/8-inch pellets at 40,000 p.s.i.g. The pellets were then placed in a tared porcelain crucible and weighed. The crucible containing the sample was placed in the bomb of a Parr adiabatic calorimeter, and the sample was burned at an oxygen pressure of 450 p.s.i.g. at 25° C. The heats of combustion of the polymer samples were obtained by applying the following corrections to the experimental values ... 

The combination of rapid mixing and fast detection systems allows cationic polymerisations to be followed on an even shorter time scale than with adiabatic calorimetry. Recent commercial stop-flow spectrophotometers have a dead time of about 15 msec, an improvement of more than one order of magnitude over previous home-made models. This implies that reactions with half lives of less than 100 msec can be analysed kinetically with a good degree of accuracy. Hi -vacuum techniques are not compatible with these instruments and all operations are therefore carried out in an inert atmosphere. 

The kinetics of the polymerization of indene in CH2CI2 solution, initiated with cumyl methyl ether and cumyl chloride, in the presence of TiCl3Bu, at variable temperatures (0 to —62 °G), have been investigated by adiabatic calorimetry under vacuum. The results may be explained by a propagation involving ionic active centers, as in conventional carbocationic polymerization.312... 

Frolova et al. [84FRO/MEL] used a vacuum adiabatic calorimetry technique to measure the low temperature (5.7 to 313.6 K) specific heat of Zr(S04)2 4H20(cr). They... 

The method of adiabatic calorimetry for specific heat measurement has been described by Collings and Smith [ ]. In the previous experiments with alloys, ground and polished surfaces achieved good thermal contact with the heater/thermometer pedestal by means of a thin layer of silicone vacuum grease. For the composites, a different specimen preparation and mounting procedure was used. Each sample was made up of five slabs (about 2.5 cm x 2.5 cm x 0.3 cm) of material cemented together, fibers parallel, with methanol-diluted GE 7031 varnish. To maximize heat transfer, one face of the laminated sample was ground... 

Thermodynamic properties of a-BN (and of y-BN) have been determined for the range of 5 to 300 K [1]. The specific heats of the cited modifications have been measured by vacuum adiabatic calorimetry the temperature dependence of Cp for a-BN is shown in Fig. 4-2 [1]. 

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