Volume expansion, contraction

The second term is the reversible work done at a given stress by the volume expansion (contraction) Vdujk if one adds dn,- to the system under stress. For uniaxial stress, this is (q = cross section area = crystal length)... 

CgLi Li l Li2jSi Li Sb Li As Li2 Sn Li22i 5 FIGURE 1.9 Volume expansion-contraction of metal alloy anodes at charge and discharge. 

During start/stop cycling the two predominant mechanisms which can affect MEA durability are (1) corrosion of the cathode owing to potential excursions to > 1.2 V (Makharia et al. 2006 Reiser et al. 2005) and (2) electrolyte redistribution owing to volume expansions/contractions. The latter mode is unique to fuel cell operation with at least partly liquid electrolytes, whereas the first is a more general mode observed also in low temperature PEFCs. 

When prepanng mobile phase mixtures each individual component should be measured out separately and only then placed in the mixing vessel This prevents not only contamination of the solvent stock by vapors from the already partially filled mixing vessel (e g ammonia ) but also volumetnc errors caused by volume expansions or contractions on mixing... 

Much of the interest in ring-opening polymerizations stems from the fact that the polymers formed may have lower densities than the monomers from which they are derived (i.e. volume expansion may accompany polymerization).168-171 This is in marked contrast with conventional polymerizations which typically involve a nett volume contraction. Such polymerizations are therefore of particular interest in adhesive, mold filling, and other applications where volume... 

S. Talabani and G. Hareland. Expansion-contraction cycles for cement optimized as a function of additives. In Proceedings Volume, pages 277-284. SPE Prod Oper Symp (Oklahoma City, OK, 4/2-474), 1995. 

It has to be noticed that no isothermal volume contraction on cooling or volume expansion on heating is associated with Tg, contrary to crystallisation or melting. The latter is a true first-order transition exhibiting a discontinuity in... 

Here V is the crystal volume, k-p and ks are the isothermal and adiabatic compressibility (i.e., the contraction under pressure), P is the expansivity (expansion/contraction with temperature), Cp and Cv are heat capacities, and 0e,d are the Einstein or Debye Temperatures. Because P is only weakly temperature dependent,... 

As previously discussed, the coefficient of expansion/contraction for petroleum products is dependent upon specific gravity. As fuels cool, their volume will be reduced. 

This view is mainly confirmed by volume contractions on mixing for these systems, which are given in Fig. 4 and in Tables 14-17. The system with nitromethane shows considerable contractions reaching 2% at the component ratio 1 1, whereas the systems with aromatic nitrocompounds show not only small contractions in most mixtures, but also volume expansion in solutions of nitrobenzene, m-xiiirotoluene and p-nitrotoluene in sulphuric acid. This behaviour is probably also due to the disruption of the structure of sulphuric acid, which is not exceeded by the volume contractions resulting from compound formation. 

Clearly, polymerization under pressure is favored in the case of Cm but not in C70. Since the polymerization is also accompanied by volume contraction in the case of Cm. pressure would indeed favor such a process. This is not so in Crn, where polymerization is accompanied by volume expansion. On the basis of these observations, we are able to understand why the atuorphization of Cm under pressure is irreversible because of polymerization. 

For gases which cause a chemical change of the surface of silica—e.g., NH3, CO, and S02—the volume expansion was preceded by a contraction. Because of the instability of the O-2 ion in surfaces, one finds that the highly degassed surface of Si02 contains O- ions as well as Si+2 ions. These quantum states are responsible for some unusual chemical reactions of the fresh surface of silica (38). 

Expansion, contraction, and volume change on resolidification measured as a function of temperature when heated. 

The importance of selecting gravimetry instead of volumetry to measure liquid amounts in the pharmaceutical industry of liquid dosage forms is well illustrated by the volume contraction of water-ethanol and volume expansion of ethyl acetate-carbon disulfide liquid mixtures as well as a CS2-ethyl acetate system. The National Formulary (NF) diluted alcohol is a typical example of the volume nonadditivity of liquid mixtures [29], This solution is prepared by mixing equal volumes of alcohol [U.S. Pharmacopeia (USP)] USP and purified water (USP). The final volume of this solution is about 3% less than the sum of the individual volumes because of the contraction due to the mixing phenomenon [1], In addition, molecular interactions of surfactants in mixed monolayers at the air-aqueous solution interface and in mixed micelles in aqueous media also cause some contraction of volume upon mixing [30],... 

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