Swelling penetrants

These observations on PVC/penetrant systems suggest a correlation of sorption kinetics with the generalized isotherm for swelling penetrants in glassy polymers, as shown schematically in Figure 9. For sorption into an initially penetrant-free glassy... 

All liquids were checked to see that they did not swell, penetrate, or otherwise interact with the substrates. The liquids were chosen to provide a wide range of positive contact angles on the substrates. Most of the liquids were identical with those used on Teflon and polyethylene by Fox and Zisman[6,8] in their studies of the critical surface tensions of solid surfaces. 

Through equation 2.17 the pseudo-equilibrium solubility can also be evaluated for the case of swelling penetrants, even in the cases in which polymer dilation is not known from direct experimental evidence. Indeed, the swelling coefficient, can be treated as the only adjustable parameter in equation 2.17, and its value can be obtained, for example, from virtually a single experimental solubility datum at high pressure for the system under considerationP J. 

The ability of the EoS to predict the behavior of rubbery polymer solutions has been proved by various authorsI ° l. In this section we present two examples of the solubility of swelling penetrants in rubbery polymers, namely propane sorption in poly[dimethylsiloxane] (PDMS) at 35° C, and then toluene sorption in rubbery polymer blends formed by low-density poly [ethylene] (LDPE) and poly[vinylchloride] (PVC) at 30° C. 

Solubility isotherms of non-swelling penetrants in glassy polymers. The sorption isotherms of CH4 in poly[phenilene oxide] (PPO) and poly[sulfone] (PSf) are now considered, as well as the sorption isotherm of N2 in poly[ethylmethacrylate] (PEMA) at... 

Table 2.7 Model parameters for the systems considered in the case of swelling penetrants...

Observations of J. C. Derksen on the influence of salts on the side chain spacing of collagen, which is a measure of intramicellar swelling (penetration of water between the chains) are consistent with the picture set forth here Thesis, Amsterdam 1935). 

The measurements can be taken under a variety of atmospheres including in vacuo, various gases and aqueous solutions. Samples can be solid (including not only film but also powder, thin-layered film, fiber), liquid or gel. TMA is used to measure linear expansion, compression, elongation, bending, swelling penetration, etc. 

Flexural gravity waves with a frequency of 0.036 Hz and a relatively small variability of 0.014 Hz occurred extensively (Fig 2a). It is believed that they are caused by long period swell penetrating from the open water area of the Greenland or Chukchi Seas. 

In each of these approaches, imaging is confined to the top of a single polymeric film by adjusting optical absorption. The penetration depth of the silylation agent and the attendant swelling of the polymer film must also be controlled to avoid distortion of the silylated image. Resists of this type are capable of very high resolution (Fig. 37). 

Methylene chloiide formulas are the most common organic chemical removers. The low molar volume of methylene chloride allows it to rapidly penetrate the finish by entering the microvoids of the finish. When the solvent teaches the substrate, the remover releases the adhesive bond between the finish and the substrate and causes the finish to swell. The result is a bhstering effect and an efficient rapid lifting action. Larger molecule solvents generally cannot... 

Similarly, polymers dissolve when a solvent penetrates the mass and replaces the interchain secondary bonds with chain-solvent secondary bonds, separating the individual chains. This cannot happen when the chains are held together by primary covalent cross-links. Thus, linear and branched polymers dissolve in appropriate solvents, whereas cross-linked polymers are insoluble, although they may be swelled considerably by absorbed solvent. 

A contusion is an injury to soft tissue in which the skin is not penetrated, but swelling of broken blood vessels causes a bmise. The bmise is caused by a blow of excessive force to muscle, tendon, or ligament tissue. A bmise, also known as a hematoma, is caused when blood coagulates around the injury causing swelling and discoloring skin. Most contusions are mild and respond well to rest, ice, compression, and elevation of the injured area. 

Solvenol monocyclic terpenes processing aid nonstaining reclaim oil and solvent swells and penetrates mbber dissolves and disperses heavy oils... 

Amines can also swell the polymer, lea ding to very rapid reactions. Pyridine, for example, would be a fairly good solvent for a VDC copolymer if it did not attack the polymer chemically. However, when pyridine is part of a solvent mixture that does not dissolve the polymer, pyridine does not penetrate into the polymer phase (108). Studies of single crystals indicate that pyridine removes hydrogen chloride only from the surface. Kinetic studies and product characterizations suggest that the reaction of two units in each chain-fold can easily take place further reaction is greatiy retarded either by the inabiUty of pyridine to diffuse into the crystal or by steric factors. 

It is possible to react an organic moiety to the hydroxyl groups on ceU waU components. This type of treatment also bulks the ceU with a permanently bonded chemical (68). Many compounds modify wood chemically. The best results are obtained by the hydroxyl groups of wood reacting under neutral or mildly alkaline conditions below 120°C. The chemical system used should be simple and must be capable of swelling the wood stmcture to facUitate penetration. The complete molecule must react quickly with wood components to yield stable chemical bonds while the treated wood retains the desirable properties of untreated wood. Anhydrides, epoxides, and isocyanates have ASE values of 60—75% at chemical weight gains of 20—30%. 

Exxon products appear to release via a unique mechanism. Like other polymer-coated technologies, the penetration of water iato the granule is purely by diffusion. However, as water enters the particle, an osmotic pressure is created as the fertilizer is solubilized. This pressure causes an expansion of the elastomeric coating and the particle swells to many times its original diameter. As the particle swells, the coating becomes increasingly thinner to the point where it caimot contain the internal pressure and the nutrient is released. 

Usually, prolonged boiling in acid water and then in alkaline water is used to stabilize NS. However, there are claims that boiling with alkaline water decreases NS stability (Ref 28). However, in a previous publication (Ref 27) these same authors claim that kler-boiling or pro-longed boiling in water or in dilute alkaline soln improves stability. Addition of substances such as epichlorohydrin that swell the NS and aid water penetration is claimed to improve stability (Ref 16)... 

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