Solvent sorption

Values of p can be determined, in principle, from any phase equilibrium data. A small table of p 2 values is available in reference (2). However, one of the most straightforward ways of determining pf values is to fit phase equilibrium data for solvent sorption in concentrated polymer solutions. To do this, equations (2) and (13) are combined to solve for p utilizing experimental partial pressure data. 

Modeling relaxation-influenced processes has been the subject of much theoretical work, which provides valuable insight into the physical process of solvent sorption [119], But these models are too complex to be useful in correlating data. However, in cases where the transport exponent is 0.5, it is simple to apply a diffusion analysis to the data. Such an analysis can usually fit such data well with a single parameter and provides dimensional scaling directly, plus the rate constant—the diffusion coefficient—has more intuitive significance than an empirical parameter like k. 

B Kabra, SH Gehrke. Rate limiting steps for solvent sorption and desorption by microporous stimuli-sensitive absorbent gels. In FL Buchholz, NA Peppas, eds. Superabsorbent Polymers Science and Technology. ACS Symp Ser 573. Washington, DC American Chemical Society, 1994, pp 76-87. 

D Biren, BG Kabra, SH Gehrke. Effect of initial sample anisotropy on the solvent sorption kinetics of glassy poly(2-hydroxyethyl methacrylate). Polymer 33 554-561, 1992. 

Predictions of Woo could be performed using global (Hildebrand) or partial (Hansen) solubility parameters, but these are very difficult (and perhaps impossible) to determine accurately from solvent-sorption experiments, so that this way is not realistic. The best experimental approach is, in our opinion, using the ultrasonic modulus. 

Solvents produce different effects than do corrosive chemicals. Both silica and carbon black filled natural rubbers were more resistant to solvents than unfilled rubber. Also, the cure time was important, indicating that the bound rubber plays a role in the reduction of a solvent sorption. The diffusion coefficient of solvents into rubbers decreases with longer cure times and higher fillers loadings. Polychloroprene rubber swollen with solvent has a lower compression set when it is filled with carbon black. 

The dynamic toluene sorption data, in (g. toluene/g. dry polymer), are shown in Figure 7. The equilibrium sorption values of toluene were measured to be about 0.075 g. solvent/g. dry polymer at RT and about 0.095 g. solvent/g. dry polymer at 50°C. This trend to increasing solvent sorption by HDPE with increased temperature has been noted by other including Corbin et al (14) for toluene and Liu et al (16) for n-hexane. The increased sorption at the higher temperature may be due to increased swelling of the polymer at the higher temperature. The lower values for the... 

As indicated in Figure 7, there is a 20- to 30-fold reduction in the steady state dynamic toluene sorption in the in situ fluorinated barrier container compared with the untreated. No significant difference in solvent uptake could be detected between the solvent-filled, treated containers stored at RT and 50°C. This is attributed to the low absolute value of the dynamic solvent sorption in the in situ fluorinated containers and the relatively small difference in equilibrium toluene sorption between RT and 50°C. 

The tensile modulus data of Figures 5 and 6 are replotted against the dynamic toluene sorption in Figures 8 and 9, respectively. In the case of the untreated HDPE containers, the loss of mechanical properties is a result of the significant solvent sorption by the polymer. The in situ fluorinated barrier reduces the solvent sorption in the HDPE and thus allows the material to retain its mechanical properties. 

Figure 8. Tensile modulus of HDPE containers exposed to toluene at room temperature versus solvent sorption. + symbols represent containers not exposed to solvent.

It was additionally calculated that the back permeation of atmospheric gases into the container was at an insufficient rate to offset vacuum development due to solvent sorption and permeation. 

The simultaneous measurements of the current-potential and frequency-potential curves are of the utmost importance to gain a better understanding of the ionie and solvent sorption processes occurring in the surface films of conducting and redox polymers, and help to establish an adequate reaction mechanism [24]. For instance, a closer inspection of the curves displayed in Fig. n.10.7 reveals... 

Equation (5.38) must be extended with (5.30) when solvent sorption plays a significant role. 

Mahesh K P O, Sivakumar M, Yamamoto Y, Tsujita Y, Yoshimizu FI, Okamoto S (2004) Structure and properties of the mesophase of syndiotactic polyst3n-ene. Vin. Solvent sorption behavior of syndiotactic polystyrene/p-chlorotoluene mesophase membranes. J. Polym. Sci. Part B Polym. Phys. 42 3439-3446... 

The indomethacin, as a model drug, was loaded into IPN disks by the solvent sorption method. The indomethacin release experiment was conducted in various conditions, changing the pH and/or the temperature of the release... 

Nakanishi Y, Shindo A (1982) Deterioration of CERP and GFRP in salt water. In Hayashi T, Kawata K, Unlekawa S (eds) Proceedings of the fourth international conference on composite materials (ICCM/4), vol 2, Tokyo. ISBS, Beaverton, OR, pp 1009-1016 Nicolais L, Apicella A, Del Nobile MA, Mensitieri G (1991) Solvent sorption synergy in PEEK. In Cardon AH, Verchery G (eds) Durability of polymer based composite systems for structural applications. Elsevier Applied Science, New York, pp 99-115 Nicolais L, Drioli E, Hopfenberg H, Caricati G (1978) Diffusion-controlled penetration of polymethyl methacrylate sheets by monohydric normal alcohols. J Membr Sci 3(2) 231-245... 

Polymers are often polydisperse with respect to molecular weight. Whereas this is of minor importance for the solvent sorption in polymers (vapor-hquid equilibrium), this fact usually remarkably influences the polymer solubility (liquid-hquid equilibrium). Therefore, polydispersity needs to be accounted for in interpretation and modeling of experimental data. This can be done by applying continuous thermodynamics as well as by choosing a representative set of pseudocomponents. It was shown that a meaningful estimation of the phase boundary is possible when using only two or three pseudocomponents as soon as they reflect the important moments (Mn, Mw, Mz) of the molecular weight distribution. 

In this chapter, an extensive study of miscibility is presented by solvent sorption methods, utilizing solvent probes to ascertain interactions existing in polymer blends. These methods employ the Flory-Huggins equation for the activity of the probe ai, in the polymer blend [1] ... 

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