Solubility increase mechanism

For diffusion of liquid through rubbery polymer composites, Fickian and non-Fickian diffusion theories are frequently used to describe the mechanism of transport, but for gas or vapour, other models have been developed to fit experimental data of diffusion profiles. The models of gas transport include Maxwell s model," free volume increase mechanism," solubility increase mechanism," nanogap hypothesis," Nielsen model, " " Bharadwaj model, ° Cussler model " " and Gusev and Lusti model, " etc. 

Solubility increase mechanism depends on the interaction between the penetrants and nanofillers. The functional groups of nanofillers such as hydroxyl when occur on the surface of the inorganic nanofiller phase in rubber composites may interact with polar gases such as SO2. This condition can increase the penetrant solubility in the nanocomposite rubbers and, in turn, increase the gas permeability. The solubility increase mechanism model due to permeation coefficient parameter of gas, P is described using the Arrhenius equation ... 

Poly(ether ether ketone) (PEEK) is an aromatic, high performance, semicrystalline polymer with extremely good thermal stability, chemical resistance, and electrical and mechanical properties. This polymer shows little solubility in organic solvents due to the crystallinity. One of the first ways to characterize PEEK was by sulfonating the polymer. By adding sulfonic acid groups to the backbone, the crystallinity decreased and solubility increased.Commercially available Victrex appears to be one of the more interesting poly(arylene ether) s used for postmodification. 

If the solubility of the third element into the precursor can be expanded, the above limitation may be decreased. By applying rapid solidification to prepare the precursor, the solubility may often be increased significantly. The other well-known process for increasing the solubility is mechanical alloying (MA). 

In the absence of calcium, /3-lactoglobulin solubility increases as pH is increased from 6.4 to 7. Addition of calcium at any pH causes a decrease in solubility. At any ratio of pH and calcium ion concentration, the increased charge on the protein induced by pH change is balanced by added calcium ions to hold the level of denaturation constant (de Wit 1981). This suggests that calcium-induced precipitation of /3-lactoglobulin occurs by an isoelectric mechanism. However, Hillier et al. (1979) found that an increase in the calcium concentration up to 0.4 mg/ml slowed heat denaturation of /3-lactoglobulin, but additional calcium had little effect. 

As a rule, the grafting of one or several methyl groups on an active molecule renders the former more lipophilic and therefore less soluble in water. However, in some particular cases, grafting one or several methyl groups to a molecule results in an increase of the water solubility by mechanisms such as the increase of hydrophobic bonding possibilities or diminution of the crystal lattice energy. 

In contrast to the previous examples, oxidative treatments may promote positive consequences in some other cases, as they decrease concentrations in phenolic acids (and other phenolics) and limit subsequent oxidations. Therefore, hyperoxidation of musts during wine processing has sometimes been proposed, and this process particularly affected HCA derivatives [27]. In addition, a peroxidasic treatment allowed the dimerization of ferulic acid in wheat bran tissues and consequently decreased arabinoxylan solubility and increased mechanical strength of the tissue [58]. 

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