Swelling maximum

Fig. 17. Adhesion energy G measured as a function of the surface density of the interfacial chains. It may noted that the strength measured in a peel test (a) is about 5 times larger than that measured using the JKR method (b). Further, a maximum exists in the value of G as function of the surface chain density. This is because of swelling effects at larger values of surface chain density. The open symbols represent the data for elastomer molecular weight Mo = 24,000 and the closed symbols represent the data for Mo = 10,000.

Sephadex type Grade Dry bead diameter (/urn) Fractionation range peptides and proteins (g/mol) Fractionation range dextrans (g/mol) Swelling factor (ml/g dry Sephadex) Maximum operating pressure" (cm H,0) Permeability Ko Maximum linear velocity" (cm/hr) Swelling time (h) ... 

When the ionic composition varies within the range of very low salt concentrations, the swelling degree can reach its maximum [101]. This behavior is observed... 

Fig. 2 a, b. Dependence of the maximum Newton viscosity (t/0) (a) and swelling ratio of the extrudate (D) (b) on the molecular mass of cis-1,4-polyisoprene, unfilled and filled to 33% by mass. Filler 1 — not 2 — CaC03 with specific surface areas 2-3 m2/g 3 — ash PM —15 with specific surface areas 12-18m2/g 4 — ash PM-100 with specific surface areas 90-100 m2/g... 

Fig. 3.12).11,12,17 In this way, a material with a higher modulus, higher strength, and less swelling is obtained and the maximum-use temperature is considerably increased. 

When a polymer relaxes at a constant anodic potential, the relaxation and partial opening of the polymeric structure involve a partial oxidation of the polymer. Once relaxed, the oxidation and swelling of the relaxed polymer goes on until total oxidation is reached this is controlled by the diffusion of the counter-ions through the film from the solution. This hypothesis seems to be confirmed by the current decay after the chronoam-perometric maximum is reached. We will focus now on the diffusion control. 

The overall sorption value tends to decrease with the addition of the nanoclays. The decrease is maximum for the unmodified-clay-fiUed sample. As the ternperamre of swelling increases, the penetrant uptake increases in all the systems (Table 2.5). The rate of increase of solvent uptake is slower for the unmodified-clay-filled sample compared to the modified one. From Table 2.5 it can be seen that the values are higher for THE compared to MEK in every composite system. The higher sorption can be explained from the difference in solubility parameter of solvent and rubber (9 — 99 and polarity. The solubility parameter value of MEK, THE, and the mbber is 19.8, 18.6, and 14.8 MPa, respectively. This difference is lower (3.8 MPa ) in the case of THE than that of MEK (5.0 MPa ). 

A hydrogel is formed by a water-soluble polymer that has been lightly crosslinked. Hydrogels swell as they absorb water but they do not dissolve. The volume expansion is limited by the degree of crosslinking. The minimum number of crosslinks needed to form a three-dimensional matrix is approximately 1.5 crosslinks per chain, and this yields the maximum expansion possible without separation of the chains into a true solution. Thus, a hydrogel may be more than 95% water and, in that sense, has much in common with living soft tissues. 

After 30-60 minutes at RH > 90%, the droplets undergo a dramatic morphological change. After reaching maximum swelling, the droplets suddenly spread, as shown in Figure 36. Separate contact-angle measurements showed that dilute sulfuric acid droplets have... 

The die-swell (extrudate swell) effect describes the significant expansion of the diameter of the fluid column after exiting from a small pipe (Figure 4.3.8(b)). Some polymer fluids can have a swelling of up to two or three times the exit diameter. A simple proposition for the mechanism of the die-swell phenomenon is that while the fluid is inside the exit pipe, it is subject to a velocity shear, similar to the pipe flow with a maximum shear stress at the wall [18]. This velocity shear stretches... 

---