Minor Phases

The presence of free lime can be very easily found under light microscope on polished section, without etching. Low amounts of humidity, which is always in the air is sufficient for very clear differentiating of these particles. 

Moore [184] was XRD determining periclase in chnker, applying selechve dis-solnhon of silicates in boric acid, or successively added acetic acid, using rathe as itmer standard. 

Alkalis show the biggest affinity to sulphur and form preferentially sulphates. In clinker K2SO4 [100, 185, 187] and Na SO [168] are formed, and can also be present as 3K2SO4 Na2SO and 2CaS04 K2SO4 [186]. The presence of former to the last phase was mentioned by Regourd [168]. Trace amounts of alkaU carbonates or potassium aluminate have also been reported to occur in some clinkers [207]. 

In 1986 Fnndal [188] found new potassium phases. In laboratory clinkers rich in potassium K O AI2O3 and free potassium oxide were present. Both phases are highly hygroscopic which influence chnker properties. 

In the case of higher alkalis content, when molar ratio (K O+NajOi/SOj excites 1, sodium forms preferentially solid solution in C3A and potassium in belite. However, there are exceptions which were discussed in points 2.5.2 and 2.5.3. 

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Another important characteristic of the late stages of phase separation kinetics, for asynnnetric mixtures, is the cluster size distribution fimction of the minority phase clusters n(R,z)dR is the number of clusters of minority phase per unit volume with radii between R and + cW. Its zeroth moment gives the mean number of clusters at time r and the first moment is proportional to die mean cluster size. 

Again consider a single spherical droplet of minority phase ( [/ = -1) of radius R innnersed m a sea of majority phase. But now let the majority phase have an order parameter at infinity that is (slightly) smaller than +1, i.e. [i( ) = < 1. The majority phase is now supersaturated with the dissolved minority species,... 

Phases Formed in Pordand Cements. Most clinker compounds take up small amounts of other components to form soHd solutions (11). Best known of these phases is the C S soHd solution called aHte. Phases that may occur Hi Portiand cement clinker are given Hi Table 1. In addition, a variety of minor phases may occur Hi Portiand cement clinker when certain minor elements are present Hi quantities above that which can be dissolved Hi other phases. Under reducHig conditions Hi the kiln, reduced phases, such as ferrous oxide [1345-25-17, FeO, and calcium sulfide [20548-54-3] CaS, maybe formed. 

Different locations of parent elements. and Th are generally located in minor phases within host rocks. Due to different U/Th ratios in these phases, recoil from the two chains may be affected by different surrounding matrix characteristics or mineral sizes. Not only might the primary distribution of U and Th be different, but earlier weathering or alteration may also have redistributed U and Th. This is discussed further below. 

As has already been emphasized in Fig. 1.1, there is the further problem of connecting the mesoscopic scale, where one considers length scales from the size of effective monomers to the scale of the whole coils, to still much larger scales, to describe structures formed by multichain heterophase systems. Examples of such problems are polymer blends, where droplets of the minority phase exist on the background of the majority matrix, etc. The treatment of... 

Triblock copolymers, as shown in Fig. 5.8 d), comprise a central homopolymer block of one type, the ends of which are attached to homopolymer chains of another type. As with other block copolymers, the components of triblocks may be compatible or incompatible, which will strongly influence their properties. Of particular interest are triblocks with incompatible sequences, the middle block of which is rubbery, and the end blocks of which are glassy and form the minor phase. When such polymers phase-segregate, it is possible for the end blocks of a single molecule to be incorporated into separate domains. Thus, a number of rubbery mid-block chains connect the glassy phases to one another. These materials display rubber-like properties, with the glassy domains acting as physical crosslinks. Examples of such materials are polystyrene/isoprene/polystyrene and polystyrene/polybutadiene/polystyrene triblock copolymers. 

The elasticity of thermoplastic polyurethane rubbers (which are also known as thermoplastic urethanes or TPUs) is a function of their morphology which comprises hard and soft phases. The hard phases consist of hydrogen bonded clusters of chain segments, which are linked by flexible chain segments that make up the soft phase. The hard blocks, which are the minor phase, exist as separate domains within a continuous matrix of the majority soft phase, as shown schematically in Fig. 25.9. 

Copolymers (graft or block) made of immiscible sequences give rise to biphasic morphologies depending on the ratio of immiscible sequences (or of their lengths). Such possible microstructures are reported in Figure 33. A minor phase can be dispersed as nodules (spheres) or filaments (cylinders) while, when concentrations of both phases get similar, lamellar (interpenetrated) structures can appear. It should be noted that rather similar morphologies could also be found in (compatibilised) polymer blends. 

Usually the discussion of the ODT of highly asymmetric block copolymers in the strong segregation limit starts from a body-centred cubic (bcc) array of the minority phase. Phase transitions were calculated using SOFT accounting for both the translational entropy of the micelles in a disordered micelle regime and the intermicelle free energy [129]. Results indicate that the ODT occurs between ordered bcc spheres and disordered micelles. 

Figure 41. The percolation threshold determination for polymer blends undergoing the phase separation. Minority phase volume fraction, fm, is plotted versus the Euler characteristic density for several simulation runs at different quench conditions, /meq- = 0.225,..., 0.5. The bicontinuous morphology (%Euier < 0) has not been observed for fm < 0.29, nor has the droplet morphology (/(Euler > 0) been observed for/m > 0.31. This observation suggests that the percolation occurs at fm = 0.3 0.01.

Thus, one could expect to find a droplet morphology at those quench conditions at which the equilibrium minority phase volume fraction (determined by the lever rule from the phase diagram) is lower than the percolation threshold. However, the time interval after which a disperse coarsening occurs would depend strongly on the quench conditions (Fig. 40), because the volume fraction of the minority phase approaches the equilibrium value very slowly at the late times. 

A needle-like morphology sometimes grows as a minority phase during the electrocrystallization process. This phase is particularly intriguing because it has notably higher Tcs (7.2-11.1 K) that approach the record for cation radical salts. (The subscript H designates the phase with the higher Tc.) To date, this phase has only been identified for six compositions, four of which contain the... 

The start-time of the last converter stage (emptying) should be equal to the starttime of the first anode furnace stage (filling). This is expressed by Eq. (5.6), where s denotes the first stage of the anode furnace. Similarly, the durations are equal, as shown in Eq. (5.7). A minor phase shift, due to the crane movements and the initial filling of the converter, could be included but since this is typically on the order of a few minutes, it has been omitted here. 

The minor phase of block copolymer microdomains are selectively removed by either chemical or physical degradation, thereby generating a defined porosity in crosslinked polymer bulk matrices or thin films... 

Fig. 9 Schematic representation of three approaches to generate nanoporous and meso-porous materials with block copolymers, a Block copolymer micelle templating for mesoporous inorganic materials. Block copolymer micelles form a hexagonal array. Silicate species then occupy the spaces between the cylinders. The final removal of micelle template leaves hollow cylinders, b Block copolymer matrix for nanoporous materials. Block copolymers form hexagonal cylinder phase in bulk or thin film state. Subsequent crosslinking fixes the matrix hollow channels are generated by removing the minor phase, c Rod-coil block copolymer for microporous materials. Solution-cast micellar films consisted of multilayers of hexagonally ordered arrays of spherical holes. (Adapted from [33])...

Diy EVOH/PP-g-maleic mldehyde (MAH) blend, obtained by moulded injection also evidenced good barrier properties for toluene. This property is improved by increasing EVOH concentration which determines both size and deformation of the minor phase increase, indicating that the laminar structure becomes more pronounced [296], But even the laminar structure is maximized a moulded injection sample is not likely to reach a permeability as low as expected for a multilayered system [296],... 

The temperature-composition diagram can be used to calculate the composition of the two-phase system according to the amount of each solvent present. For example, at temperature T, the composition of the most abundant phase, which consists of liquid A saturated with liquid B, is represented by the point a and the composition of the minor phase, consisting of liquid B saturated with liquid A, is represented by point a. The horizontal line connecting these two points is known as a tie line as it links two phases that are in equilibrium with each other. From this line the relative amounts of the two phases at equilibrium can be calculated, using the lever rule, under the conditions described by the diagram. The lever rule gets its name from a similar rule that is used to relate two masses on a lever with their distances from a pivot, i.e. ... 

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