DYNAMIC THERMAL

The relative effectiveness of nucleating agents in a polymer can be determined by measuring recrystallization exotherms of samples molded at different temperatures (105). The effect of catalyst concentration and filler content has been determined on unsaturated polyesters by using dynamic thermal techniques (124). Effects of formulation change on the heat of mbber vulcanization can be determined by dsc pressurized cells may be needed to reduce volatilization during the cure process (125). 

To describe rhe dynamic thermal behavior of the envelope and internal structural elements, the following two methods are most often used In thermal building simulation codes ... 

Due to the thermally driven air exchange and the large building masses involved, the problem must be studied using a dynamic thermal building mode) wirh an integrated ventilation model. 

The chromium oxides were prepared according to the following procedure [6-8]. Chromium oxide resulted from the dehydration of chromium hydroxide obtained by the addition of an ammonia solution (5M) to a solution of chromium nitrate (0.5M) The final pH was equal to 7.5 and the hydroxide formed was kept constantly stired and heated at 80°C for 1 h so as to obtain complete precipitation. This solid was filtered and washed three times with hot distilled water and dried for 16 h in an oven at 90°C. It was then submitted to a dynamic thermal treatment under nitrogen at 380°C for 8 h. The chromium oxide formed was cooled down under the same vector gas. 

Carmon, T. Yang, L. Vahala, K. J., Dynamical thermal behavior and thermal self stability of microcavities, Opt. Express 2004, 12, 4742 4750... 

A technique is described [228] for solving a set of dynamic material/energy balances every few seconds in real time through the use of a minicomputer. This dynamic thermal analysis technique is particular useful in batch and semi-batch operations. The extent of the chemical reaction is monitored along with the measurement of heat transfer data versus time, which can be particularly useful in reactions such as polymerizations, where there is a significant change in viscosity of the reaction mixture with time. 

But absolute zero is unattainable, so all particles move. Furthermore, the particles never retain an invariant speed because inelastic collisions cause some particles to decelerate and others to accelerate. As a result, everything emits some electromagnetic waves, even if merely in the context of a dynamic thermal equilibrium with the object exchanging energy with its surroundings. 

Pressure design of unlisted components and other piping elements to which the rules in para. IP-3.1 do not apply shall be based on calculations consistent with the design criteria of this Code. These calculations shall be substantiated by one or more of the means stated in (a) through (d) below, considering applicable dynamic, thermal, and cyclic effects in paras. IP-2.1.7 through IP-2.1.8, as well as thermal shock. Calculations and documentation showing compliance with (a), (b), (c), or (d), and (e) shall be available for the owner s approval ... 

Nj and Oj in equation (2.4) represent the number of atoms in the jth shell and root-mean-square deviation of the interatomic distances over Rj which results both from static and dynamic (thermal) disordering effects respectively. The scattering amplitude, Fj(k) is given by... 

Other thermal techniques are Thermogravimetric Analysis (TGA) [55,68], High Pressure Calorimeter (HPC) [1], Thermomechanical Analysis (TMA) [1,141], and Differential (or Dynamic) Thermal Analysis (DTA) [74]. These are rarely used and will not be discussed here. 

PVC/EPR exhibits good processability as shown by fluidity, homogeneity, hot tenacity of the melt, specific power absorption, and dynamic thermal stability. 

Equation (9.19) is the most basic equation for the dynamic thermal analysis of an SOFC cell/stack. As one would expect, the equation shows that under steady state, the change in enthalpy from inlet to exit is equal to the internal heat generation within the system. 

In most cases, scale-up by similarity is not always fully achieved. A process may be geometrically similar, but not thermally similar. Depending on the type of process involved, one or several kinds of similarities may be required. These may be geometric, kinematic, dynamic, thermal, kinetic or chemical similarities. 

Barker, J.A. and Auerbach, D.J. (1984). Gas-surface interactions and dynamics Thermal energy atomic and molecular beam studies, Surf. Science Reports 4, 1-99. 

The current method of determining the energy properties of polyurethane is the Dynamic Thermal Mechanical Analyzer (DTMA). This instrument applies a cyclic stress/strain to a sample of polyurethane in a tension, compression, or twisting mode. The frequency of application can be adjusted. The sample is maintained in a temperature-controlled environment. The temperature is ramped up over the desired temperature range. The storage modulus of the polyurethane can be determined over the whole range of temperatures. Another important property closely related to the resilience, namely tan delta (8), can also be obtained. Tan (8) is defined in the simplest terms as the viscous modulus divided by the elastic modulus. 

Fig. 19. Dynamical thermal stability of electric field poling-induced electro-optic activity for two samples. The data were obtained as described in [121] by slowly increasing temperature while monitoring second harmonic generation. The chromophore is a DEC chromophore described in [138]. Uncrosslinked refers to the precursor polymer where only one end of the DEC chromophore is attached to the polymer lattice. Crosslinked refers to the situation where both ends of the DEC chromophore have been reacted to achieve covalent coupling to the polymer lattice. The ends of this DEC chromophore are asymmetrically functionalized so that attachment reactions can be carried out independently...

Fig. 21. Dynamic thermal stability [121] of a variety of polymeric electro-optic materials. All materials involve the Disperse Red chromophore. Trace 1 PMMA composite material trace 2 chromophore covalently attached by one end to a soft (PMMA-like) matrix [138] trace 3 DEC chromophore with both ends attached to a soft polymer matrix [138] trace 4 Disperse Red chromophore covalently attached at one end to a polyimide polymer matrix [121] trace 5 DEC-type chromophore with both ends attached to a sol-gel type matrix [139]...

Although it is basically possible to apply the theory of similarity to chemical processes and to scale up one of these processes in such a way that geometric, fluid dynamic, thermal and reaction-kinetic similarity is retained to a greater or lesser extent, these transformation processes are only of limited importance. They may be quite useful for increasing equipment performance two to five-fold but hardly to much larger amounts. This circumstance is of importance since it is more or less equivalent to practical failure of the theory of similarity. This, however, was not to be expected from the beginning, especially in view of the fact that the theory of simila-... 

Because all of the coordinating atoms in a shell are not fixed in position at exactly R the term a2 in e accounts for the disorder in the interatomic distances. The term has contributions from dynamic (thermal) disorder and static disorder (structural). 

Polybutene has also been shown to improve impact resistance and dynamic thermal stability in impact modified PVC-U formulations (433). 

The addition of polybutene to impact modified PVC formulations reveals improved impact resistance and increased dynamic thermal stability in the PVC formulation. Polybutene added at levels up to 10% of the total impact modifier gives a significant increase in the Izod impact and increase in dynamic thermal stability by as much as 25%. 6 refs. 

Folmer-Andersen JF, Lehn J-M (2011) Thermoresponsive dynamers thermally induced, reversible chain elongation of amphiphilic poly(acylhydrazones). J Am Chem Soc 133 10966-10973... 

Under dynamic-thermal conditions [38], the onset temperature at which the reaction between the solid and the gas phase starts, detected by a sudden increase in weight... 

The pure components, as well as IPNs produced at various ratios, were characterized by density measurements, dynamic thermal mechanical analysis, and electron microscopy. Results are presented and discussed below. 

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