Single-phase mixtures

A solution is a single-phase mixture of more than one compound, and the driving force for its spontaneous formation from the pure compounds at constant T and p is the negative Gibbs free energy change of the mixing process, —AG, as... 

Although mixtures of most polymers form two-phase systems with two glass transitions, some mixtures do form one phase with a single Th. An example of a single-phase mixture is poly(vinyl acetate) (Th - 35°C) and poly(methyl acrylate) (TR = 14°C). What is the approximate TK value of a mixture containing equal volumes of the two polymers ... 

Curve defining the region of composition and temperature in a phase diagram for a binary mixture across which a transition occurs from miscibility of the components to conditions where single-phase mixtures are metastable or unstable (see Note 4 in Definition 1.2). 

Therefore, it is only possible to obtain a homogeneous, single-phase mixture of two polymers when the generally slightly positive mixing enthalpy AH j is sufficiently small or its magnitude is smaller than TAS. However, this is only to be expected for chemically very similar macromolecules. 

Two typical experiments have been selected for discussion the experiment 5 which belongs to the first series (rapid expansion of a single-phase mixture with continuous feeding in CO2) and the experiment 15 of the fifth series (rapid expansion of a two-phase stirred mixture). 

Single phase mixtures of partly incompatible polymers, and... 

The miscibilities of the components in polymer blends is often ascertained by the measurement of the material s glass transition temperature (Tg). The mixing of two polymers with no mutual interactions usually results in the mixture having two separate phases each with their own distinct glass transition temperature. However, when the two components do interact to form a single phase mixture, their glass transitions combine and there will be the emergence of only one transition temperature that is linearly dependent on composition [118]. 

Why are large molecules such as polymers less likely to mix (in the sense of forming single phase mixtures) than small molecules ... 

The liquid contains varying quantities of water which forms a stable single phase mixture, ranging from about 15 wt% to an upper limit of about 30-S0wt% water, depending on how it was produced and subsequently collected. Pyrolysis liquids can tolerate the addition of some water, but there is a limit to the amount of water, which can be added to the liquid before phase separation occurs, in other words the liquid cannot be dissolved in water. It is miscible with polar solvents such as methanol, acetone, etc. but totally immiscible with petroleum-derived fuels. 

Bio-fuel oil consists of a single phase mixture of water and organics. 

If there is a net attraction between species (i.e. they like each other better than they like themselves), x < 0 single-phase mixture is favourable... 

Since zero-C02 concentration is taken as a reference condition, the parameter is not a function of CO2. Then, f, oc, and jS can be determined from the PVT measurement of the neat polymer. There remains only gas concentration coefficient, (p, a. a. variable affected by CO2 dissolution. The gas expansion coefficient, (p, is determined by solubility measurements, the models with these parameter values could predict the viscosity of polymer/C02 single-phase mixtures. ... 

Essentially the mixing point gives the composition of a hypothetical single-phase mixture formed from the two feed streams. According to a mass balance, this is the same mixture which would be formed by mixing the two product streams. In other words, M is the mixing point for either Lq and V2 or Lj and Vj. 

An ideal solution is never unstable and will always remain as a single phase mixture. To prove this, we need to demonstrate that /dx is always positive. For a binary mixture, the molar Gibbs free energy of an ideal solution is given by... 

THERMODYNAMIC PROPERTIES OF SINGLE-PHASE MIXTURES 1.3.1 Density... 

Several mixtures with different silicone oil concentrations were prepared. Since the temperature quenches are performed from the nematic domain (N), the maximum weight fraction of silicone oil investigated was 0.035. When the sample is thermally quenched from the nematic domain (typically, 55°C) to the diphasic domain (20°C), the uniform single-phase mixture is thermodynami-... 

Table 8.5 compares different exchange coefficients calculated from the data for ammonium-calcium exchange in Table 8.2. The simple Gapon equation (8.10) yields the most uniform exchange coefficient for this set of data the Eriksson equation s predictions also agree well with the measured values. Bond and Verburg (1997) applied the various ion equations to the more complicated case of ternary (Ca-K-Na). Their slight modifications of the 1918 work by Rothmund and Kornfeld yielded the most consistent exchange coefficients in their study. Snyder and Cavallaro (1997) applied a single-phase mixture approach to NH -Ba2+-La3+ exchange on clays.

It was shown that amorphous polymers certainly reside between crystal lamellae as a single phase mixture in poly(8-caprolactone) (PCL)/poly(vinyl chloride) (PVC) blends [Stein, 1978]. When the content of the amorphous polymer is high, its excess is excluded from interlamellar region to the outside of lamellar stacks in poly(etheretherketone)/ poly(etherimide) blends [Lee et ah, 1997]. 

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