Swelling

About: Swelling is a research topic. Over the lifetime, 8395 publications have been published within this topic receiving 200488 citations.

Statistical mechanics of cross-linked polymer networks ii. swelling

Abstract: The interaction of solvents with cross‐linked network structures, such as occur in vulcanized rubber, is subjected to a statistical mechanical treatment based on the model and procedure presented in the preceding paper. The activity of the solvent is expressed as a function of its concentration in the swollen network, and of the degree of cross‐linking. The maximum degree of swelling of the network in contact with the pure solvent is related to the degree of cross‐linking. The heat of interaction of the solvent with the network can be calculated from the temperature coefficient of maximum swelling. The theory leads to the conclusion that the swelling capacity should be diminished by the application of an external stress. Furthermore, the modulus of elasticity should decrease inversely with the cube root of the swelling volume.

Nanocomposite Hydrogels: A Unique Organic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling/De‐swelling Properties

Abstract: Novel nanocomposite hydrogels (NC gels) with a unique organic-inorganic (clay) network structure (see Figure) have been synthesized by in-situ free radical polymerization. The resulting NC gels exhibit high structural homogeneity, superior elongation with near-complete recovery, good swellability, and rapid deswelling in response to temperature changes.

Kinetics of swelling of gels

Abstract: We present a theory of the kinetics of the swelling of a gel. The characteristic time of swelling is proportional to the square of a linear dimension of the gel and is also proportional to the diffusion coefficient of the gel network, which is defined as D=E/f where E is the longitudinal bulk modulus of the network, and f is the coefficient of friction between the network and the gel fluid. This constitutes an essential difference between the present theory and the previous theory which is based on the assumption that the swelling time is determined by the diffusion coefficient of the fluid molecules. Experimental data are shown for spheres of 5% polyacrylamide gels and are analyzed using the present theory. The value of the diffusion coefficient obtained from the macroscopic swelling experiments shows excellent agreement with that obtained microscopically using laser light scattering spectroscopy.

On the mechanism of water holding in meat: The swelling and shrinking of myofibrils

Abstract: Water holding in meat has, in the past, been rather poorly understood and has not been explained at all in structural terms. A unifying hypothesis for this phenomenon is that gains or losses of water in meat are due simply to swelling or shrinking of the myofibrils caused by expansion or shrinking of the filament lattice. Myofibrils have been observed by phase contrast microscopy, and are seen to swell quickly to about twice their original volume in salt solutions resembling those used in meat processing. Such swelling is highly co-operative. Pyrophosphate reduces very substantially the sodium chloride concentration required for maximum swelling. In the absence of pyrophosphate, swelling is accompanied by extraction of the middle of the A-band; in its presence the A-band is completely extracted, beginning from its ends. We suppose that Cl(-) ions bind to the filaments and increase the electrostatic repulsive force between them. A crucial factor in swelling is likely to be the removal at a critical salt concentration of one or more transverse structural constraints in the myofibril (probably crossbridges, the M-line or the Z-line) allowing the filament lattice to expand. We also point out that water losses in rigor, in the PSE condition and on cooking may well result directly from shrinkage of the filament lattice.