Mechanical and Thermal Analysis

Some zeolites such as AIPO4-5 (API) have a negative coefficient of thermal expansion over certain temperature ranges [230, 231]. For a zeolite formed into a pellet, one method to verify the presence of a negative coefficient of thermal expansion is by thermal mechanical analysis (TMA). For just the zeolite, powder X-ray diffraction at various temperatures can be used. Such an analysis can be of importance for identifying pellet strength or vessel containment issues. 

Of the various mechanical properties of a formed catalyst containing zeolite, attrition resistance is probably the most critical. This is particularly the case for FCC catalysts because of the impact on the addihon rate of fresh catalyst, particulate emissions of fines and overall catalyst flow in the reactor and regenerator. Most attrition methods are a relative determination by means of air jet attrition with samples in the 10 to 180 xm size range. For example the ASTM D5757 method attrites a humidified sample of powder with three high velocity jets of humidified air. The fines are continuously removed from the attrition zone by elucidation into a fines collection assembly. The relative attrition index is calculated from the elutriated fines removed at a specific time interval. 

Thermogravimetry can be used to measure the amount of water [232] or other molecule adsorbed on a zeolite. DSC can be uhlized to study the thermal effects during adsorption and desorphon of water [233] because the peak area under the heat flow time curve is related to the sorption heat. 

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SAXS and WAXS are particularly efficient in the study of amorphous polymers including microstructured materials, hence their use in block copolymers (see also Chapters 6 and 7). The advent of synchotron sources for X-ray scattering provided new information, particularly on the evolution of block copolymer microstructures with time resolution below one second. In particular, the morphology of TPEs is most often studied with these techniques Guo et al. [108] applied SAXS to the analysis of the phase behavior, morphology, and interfacial structure in thermoset/thermoplastic elastomer blends. WAXS is often associated with SAXS and some other methods, such as electron microscopy, and various thermal and mechanical analyses. It is mainly used in studies of the microphase separation [109,110], deformation behavior [111], and blends [112]. 

For the overpower type transients, the Umiting failure mode is expected to be burst or pellet cladding mechanical interaction (PCMI). The maximum allowable powers listed in Table 2.8.1 are determined through the fuel rod thermal and mechanical analyses in Chap. 2, taking several conservatisms so as to prevent melting of the pellet centerline and keep the circumferential strain on the cladding... 

Thermal and Dynamic Mechanical Analyses. The thermal and mechanical properties of the new photocured films were evaluated by DMA and TGA. The initial DMA scan of the photocured polymer (prepared from a 3 1 blend of 4-allyloxystyrene DVE-3) to ensure crosslinking on UV exposure shows two transitions at 62°C and 232°C, as shown in Figure 4, scan a. The low temperature transi-... 

From the analyses of NMR and electron-spray ionization mass (ESI-MS) spectroscopy, the polymers obtained from the polymerization of cyclic disulfides were found to be a cyclic structure [202], The cyclic structure consisting of poly(DT) is assumed to be formed by a backbiting reaction of propagating species [203]. Thermal and mechanical properties of the polymers, and decomposition behaviors of the polymers demonstrate that the polymers obtained from thermal polymerization of cyclic disulfides include a polycatenane structure. From polymerization of cyclic disulfides in the presence of cyclic polyethylene oxide), a polycatenane consisting of two different cyclic polymers was obtained [199]. Thus, poly(DT) contains spatial entanglements of cyclic polymers with each other (a polycatenane structure was presumed) (Fig. 61). 

In view of the fact that the most important goal of the CHP systems described here is to achieve the interconversions of chemical, thermal, and mechanical energies with the highest efficiency and the lowest losses, these systems are ideal subjects of thermodynamic analyses. Since there are no chemical raw materials consumed and since the only delivered products are heat and work, thermodynamic efficiency of the overall process plays a vital role in the design and economics of such systems. It 1s the purpose of this report to present the results of two separate applications of the second law analysis to these chemical energy systems. 

To investigate the behaviour observed in both the Isothermal Test and Buffer Container Experiment numerical simulations have been undertaken. In particular coupled hydraulic-mechanical analyses of the Isothermal test and thermal-hydraulic-mechanical analyses of the Buffer Container Experiment have been undertaken. These analyses have been performed via a finite element computer code, COMPASS (Thomas and He, 1997 1998). 

Systems used for accident mitigation should be designed to withstand the maximum loads, stresses and environmental conditions for the accidents analysed. This should be assessed by separate analyses covering environmental conditions (i.e. temperature, humidity or chemical environment) and thermal and mechanical loads on plant structures and components. 

H. Anderson [11] used differential thermal and thermogravimetric analyses to confirm the free radical mechanism of the thermal decomposition of epoxide resins, proposed by M. B. Neiman and associates. It was shown in this work that an important stj e in the pyrolysis of an epoxide resin is isomerization of the epoxide group to a carbonyl, which is accompanied by an exothermic effect and is observed in the temperature interval 350-400°C. The thermogravimetric curves confirmed that the rate of pyrolysis of samples of epoxide resins hardened with maleic anhydride is less than that of samples hardened with amines (metaphenylenediamine). 

Also studied were PB A- and PCL-based SMPU fibers, spun by the wet-spinning process. The effects and mechanisms of thermal-humidity treatments on the shape memory properties of PBA-based SMPU fibers were examined based on mechanical, thermal and chemical analyses. The ejqrerimental results show that PBA-based SMPU fibers are not as sensitive to water as PCL-based fibers. The reduction of shape memory properties after high-temperature conditioning is... 

As an example, in order to analyse ceramic structures in thermally and mechanically high loaded diesel engines during the most important running states it is necessary to combine experimental techniques with numerical methods. Numerical simu-... 

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