Subject index stability

Thermoplastic elastomers (TPEs) with blocks of polydiene rubber are subject to degradation at the carbon-carbon double-bond sites and require proper stabilization. In SIS block copolymers, chain scission is the predominant degradation mechanism. In an SIS block copolymer, the addition of a more effective stabilizer, AO-3, alone or blended with a secondary antioxidant, PS-1, can provide a significantly superior performance over AO-1 alone or with PS-1. Resistance to discoloration after static oven aging at 80°C (176°F) is improved dramatically (Fig. 5). Viscosity stabilization (melt flow index stability) (Fig. 6) is also improved drastically using AO-3/PS-1. 

More quantitative data can be obtained either from reference books or from computerized databanks. Let us deal first with the books. A selection of ionization constants is given in Albert and Serjeant (1984). Exhaustive compilations of ionization constants are listed on p. 383. Recently determined values may be located through Chemical Abstracts through the entry Ionization in Liquids in the General Subject Index, or under the name of the particular substance in the Chemical Substance Index. For the prediction of ionization constants from the chemical structure, see Perrin, Dempsey and Serjeant (1981). The standard compilations of the stability constants of chelated metals are given at the end of Section 11.3 (p. 459). 

Ionic liquids are a class of solvents and they are the subject of keen research interest in chemistry (Freemantle, 1998). Hydrophobic ionic liquids with low melting points (from -30°C to ambient temperature) have been synthesized and investigated, based on 1,3-dialkyl imidazolium cations and hydrophobic anions. Other imidazolium molten salts with hydrophilic anions and thus water-soluble are also of interest. NMR and elemental analysis have characterized the molten salts. Their density, melting point, viscosity, conductivity, refractive index, electrochemical window, thermal stability, and miscibility with water and organic solvents were determined. The influence of the alkyl substituents in 1,2, 3, and 4(5)-positions on the imidazolium cation on these properties has been scrutinized. Viscosities as low as 35 cP (for l-ethyl-3-methylimi-dazolium bis((trifluoromethyl)sulfonyl)amide (bis(triflyl)amide) and trifluoroacetate) and conductivities as high as 9.6 mS/cm were obtained. Photophysical probe studies were carried out to establish more precisely the solvent properties of l-ethyl-3-methyl-imidazolium bis((trifluoromethyl)sulfonyl)amide. The hydrophobic molten salts are promising solvents for electrochemical, photovoltaic, and synthetic applications (Bon-hote et al., 1996). 

Accelerated stability tests using the emulsion volume index (EVI) Accelerated aging procedure in which an emulsion in a microhematocrit tube is subjected to centrifugal force EVI = (length of emulsion phase/lolul length of column) (% fal/0.9) x 100. A higher EVI indicates a more stable emulsion under the conditions of the test. 

This book is based predominantly on the patent literature and provides how to data regarding the production, purification, and application of commercial enzymes. Coverage is not limited to food applications, and 70 subjects are grouped as Enzymes, Enzymatic Processing, Enzyme Stabilization, Polymer-Enzyme Products, Cell Culture, Protein Analysis, Nucleic Acids etc.. Amino Acids, Peptide Synthesis, and Applications. Indexing includes U.S. patent number, company and patent assignee, inventor, and subject. 

Still there are efforts to improve the performance of natural mineral oil-based lubricants by the synthesis of oligomeric hydrocarbons, which has been the subject of important research and development in the petroleum industry for many years and has led to commercialization of a number of synthetic lubricants. These materials are based on the oligomerization of a-olefins such as C6-C20 olefins. Industrial research effort on synthetic lubricants has generally focused on improved viscosity index, thermal and oxidative stability, and a pour point equal to or better than that of the corresponding mineral oil lubricants. 

Ye and co-workers exploited the shear stability of highly branched, high molecular weight polyethylenes (PEs) as lubricant viscosity index improvers [252, 253]. Viscosity index of a lubricant is a critical parameter which defines its quality and application temperature range. They synthesized PEs with controllable chain topologies ranging from linear to a hyperbranched dendritic structure by chain walking polymerization [254]. The PE samples were blended into a base paraffinic oil (density 0.8659 g mL at 15 °C, kinematic viscosity 30.06 cST at 40 °C) to form lubricants. The lubricants were subjected to the Kurt Orbahn (KO) test to measure the shear stability index, which is expressed by... 

The stability of HPMCAS at higher temperatures for shorter periods of time has been examined to understand its behavior while considering processes such as HME (Shin-Etsu Chemicals Co., Ltd). In this study, the stability was tested at 150-180 °C, for 15-30 min. A powder sample was stored in an oven, and the tests were carried out according to Japanese Pharmaceutical Excipients (JPE), with the exception of the yellowness index, which was measured using a color computer. The observed changes were a decrease in viscosity (due to a decrease in the molecular weight of the polymer), an increase in free acid, and discoloration. From the results, it is suggested that the polymer itself will be fairly stable up to about 150 °C when subjected to this temperature for a short period of 15 min. The results are shown in Table 4.3. 

The erosion resistance of soil may be classified not only in terms of the coefficient of stability (protection) (see page 379), but also by means of other indices. Thus another suitable index for the erosion resistance of soils containing sand particles is the ratio of the total amount of sand to the total amoimt of silt and silt fractions. This ratio equals 3.6 and 2.9, respectively, in noneroded sandy-loam black-earth and dark-chestnut sandy-loam soils, while in the eroded soils it reaches 6.6 and 5 2, i.e., it doubles. In places of severe and repeated erosion the ratio rises to 9. Soils containing a large quantity of sand and relatively few of the type of particles which give the quality of cohesion to the ground are more subject to erosion [504]. 

Quality of Life Index (LQI), was developed by the British magazine The Economist, aims to reflect in a more appropriate manner and level of life satisfaction in different countries. The LQI are combined the results of subjective life satisfaction of objective factors of quality of life. Parameters and quality of life measures, which are used to identify parameters include financial situation, health, political stability and security, family life, community life, climate and geography, job security, political freedom and gender equality. The original definition of LQIis as follows (Nathwani et al.) ... 

Aromatic compounds are important in industry as well as in living systems and clusters are important in many areas such as photography, catalysis, and quantum dots. Apart from the basic aspects of aromaticity, experts discuss the structures, properties, reactivity, stability, and other consequences of aromaticity of a variety of metal clusters in this volume. The Foreword was written by Professor Paul v. R. Schleyer, an authority in this subject and the originator of the nucleus-independent chemical shift (NICS) index, the most widely anployed measure of aromaticity. This book will be useful for graduate students as well as researchers in this field. 

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