Thermal stability of materials

Somov Al, Chernykh OV (1967) Thermal Stability of Materials and Structural Components 4 76... 

Reduction of thermal stability of material to point of initiating decomposition. 

Information about the thermal stability of materials and mixtures can be obtained with little effort. It is known that when certain functional groups are present an increased probability of exothermic decomposition needs to be accounted for. A list of special compounds and materials are given in the Appendix (section G 1). 

Differential thermal analysis ("DTA") is a measuring method which makes it possible to study the heat transfer during physical and chemical reactions. This can be done with small samples (usually a few milligrams). This analysis is suited for studying the thermal stability of materials and can in many cases be used to assess the thermal potential of chemical reactions. 

Critical temperatures of substances vary over a wide range, allowing for SCF selection for specific applications. Supercritical CO2 is especially useful in the food and pharmaceutical industries where toxicity of the extraction medium, solvent entrapment, and thermal stability of materials are concerns. Specifically, SCFs required for processing thermally labile compounds such as proteins and peptides should have a critical temperature that is close to ambient conditions (e.g., CO2 and ethylene with critical temperatures of 31.1°C and 9.3°C, respectively). 

Kinetic analysis allows one to solve an important practical task of predicting thermal stability of materials outside the temperature region of experimental measurements. Thermal stability can be evaluated as the time to reach a certain extent of conversion at a given temperature. Rearrangement of equation (4) gives... 

E 1952 (1998) Thermal Diffusivity/Conductivity by MTDSC E 1953 (1998) Description of Thermal Analysis Apparatus E 1970 (1998) Statistical Treatment of Thermal Analysis Data E 1981 (1998) Guide for assessing the thermal stability of materials by the method of Accelerating Rate Calorimetry... 

Metal chelates lower decomposition temperature (decrease thermal stability of material), increase char yield and limiting oxygen index, and improve smoke density rating. They are useful S5mergistic additives for Al(OH)3 and Mg(OH)2. Their two major functions are catalysts of dehydrochlorination and char formers. 

Thermal Analysis techniques [differential scarming calorimetry (DSC) and thermogravimetric analysis (TGA)], have been used widely to provide a measurfe of the thermal stability of materials. These methods are compUcat when it is desired to measure the stability of volatile organic compounds like many of the proposed NLO chromophores. Methods are needed that can distinguish between volatilization and decomposition. 

The TGA is a branch of thermal analysis which examines the mass loss of a material as a function of temperature, time, and sometimes environment. The main usage of this instrument is to characterize the decomposition temperature T or to investigate the thermal stability of materials under a variety of conditions. In addition, it is also used to study the kinetics of the physicochemical processes of materials. 

There are several reasons to dope in host lattices which comprise s-block or transition metal ions. Naturally, for hghting purposes, a host lattice with Ca, say, instead of Y, would be cost-effective. In other applications, the thermal stability of materials such as AI2O3 would be advantageous. Upon doping, it is necessary to determine the location of the lanthanide guest in the host lattice. 

Chapter 20 Thermal Stability of Materials in Lithium-Ion Cells 465... 

GB/T 13464-92 Thermal Analysis Test Method for Thermal Stability of Materials... 

It should be noted that the reduction of thermal stability of material with a small grain size is a well-known fact for metal nanoparticles (Jiang and Shi 1998 Shim et al. 2002 Jiang et al. 2004 Xie et al. 2006 Li et al. 2008b). When the size of nanoparticles is less than 10-20 nm, melting temperature drops sharply in comparison with conventional bulk materials. This effect is a consequence of the... 

Figure 10.12 shows the effect of the content of a polyolefin release agent on the reduction of ejection pressure. With fatty acid amides, the reduction of ejection pressure is even more pronounced, but their presence may affect impact properties and thermal stability of materials. Polyolefin release agents were found to not affect mechanical and thermal properties of polyetherimide. 

TGA is often used to determine the relative stability of materials. This is carried out by observing the onset temperature, in a given atmosphere, of the decomposition of the polymer. Since the majority of polymers are used in real life scenarios, the atmosphere usually chosen is air. It is also possible though to assess relative thermal stability of materials that are used in service under adiabatic conditions, for example rubber seals that are immersed in oil. It is always important to remember in these cases though that the actual lifetime of the material will also be influenced by the media that it contacts and not just the temperature that it is exposed to. 

TGA is used for determining volatiles content and/or thermal stability of materials, by monitoring the weight loss on heating (see Section 3.4.1). 

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