Search results for "Isochoric process"
showing 4 items of 4 documents
Liquid/Gas and Liquid/Liquid Phase Behavior of n-Butane/1,4-Polybutadiene versus n-Butane/1,2-Polybutadiene
2005
Solutions of 1,4-polybutadiene (1,4-PB, 98% cis) and of 1,2-polybutadiene (1,2-PB) in n-butane (n-C 4 ) were studied with respect to their vapor pressure and to their demixing into two liquid phases under isochoric conditions within the temperature range from 25 to 75 °C. 1,2-PB mixes homogeneously with n-C 4 at any ratio, in contrast to 1,4-PB, which exhibits a miscibility gap extending from practically pure solvent to approximately 40 wt % polymer. Corresponding to these solubility differences, the vapor pressures for the system n-C 4 /1,4-PB are considerably higher than for n-C 4 /1,2-PB at the same concentration and temperature. The experimental results are modeled accurately and consis…
Molecular association in low-temperature and high-pressure polymorphs of 1,1,1,2-tetrachloroethane
2010
Interactions and aggregation of 1,1,1,2-tetrachloroethane molecules, Cl3CCH2Cl, have been investigated at low temperature and high pressure. Isobaric and isochoric crystallizations led to two polymorphs, characterized by single-crystal X-ray diffraction. The low-temperature polymorph α is monoclinic, space group C2/c, with molecules orientationally disordered in two sites at the temperature independent 70:30 rate. In isothermal conditions (295 K) 1,1,1,2-tetrachloroethane freezes at 0.73 GPa. The high-pressure polymorph β is monoclinic, space group P21/c, with the molecules fully ordered. The molecular aggregation at varied thermodynamic conditions results from the interplay of halogen inte…
Relations between compression and thermal contraction in 1,2,4-trichlorobenzene and melting of trichlorobenzene isomers
2015
The compression and thermal expansion of crystalline 1,2,4-trichlorobenzene, C6H3Cl3, 124TCB, investigated under isobaric and isothermal conditions, are in reverse relation, as for most of crystals, however, the isochoric strain along direction c is clearly different from those along a and b. Single crystals of 124TCB have been in situ grown under isochoric and isobaric conditions, at 270 K/0.1 MPa and 295 K/0.16 GPa, and also at 100 K/0.1 MPa and 295 K/0.64 GPa, when the unit-cell volume is similar. All crystallizations yielded the same phase, of monoclinic space group P21/n, with two symmetry-independent molecules (Z′ = 2). The structure is governed by Cl⋯Cl and Cl⋯H interactions and the …
How can freezing water burst pipes and containers?
2018
When a water pipe or a tank completely filled with water is cooled, ice formation generates a pressure which can cause it to burst. This phenomenon is due to the fact that water increases in volume when freezing—but how to explain the expansion force of freezing water? Our aim in this paper is to show that in the case of a total phase change, even the best steels could not prevent bursting. It is also to show how ice formation occurs in isochoric cooling (constant volume) when a container that is full of water is strong enough to prevent water expansion. At the end of the paper, we give some examples taken from everyday life.