Swelling of elastomers

As In the case of ethanol and methanol a high swell of the elastomers in MTBE mixtures leads to decreased tensile strength and elongation as shown In Table V. Addition of toluene to Indolene HO-III to make "spiked" Indolene leads to Increased swell of elastomers In this fuel and Its mixtures (Tables V and VI). In the case of all the six polymers Investigated increasing the aromatic content from 30 to 50% has a more detrimental effect on elastomers than the addition of 10% MTBE (Table VI). 

Swelling of elastomers by liquid is known to be a diffusion controlled process and up to the equilibrium swelling ratio, the volume of liquid absorbed is proportional to the square root of the time during which the elastomer has been immersed in the liquid. For most liquids, the rate of penetration depends also upon the viscosity of the swelling liquid rather than its chemical nature. 

The values of parameters Xn and X23 were calculated from the Flory-Rehner equation, using data on swelling of crosslinked polymer in individual solvents, the values Xn X23 > and %i23 were estimated from Eqs. [6.2.3-6.2.5). Then equilibrium swelling of elastomer in SL was calculated from the equation similar to Flory-Rehner equation, considering the mix-... 

Results of calculation of the liquid phase composition at maximum swelling of elastomer correlate with the experimental data (see Table 6.2.2). The approach predicts the existence of an extremum on the swelling curve. This increases the forecasting efficiency of the prediction. 

Baba, M. Nedelec, J.-M. Billamboz, N. Lacoste, J., Porous Volume of Inorganic Materials and Degree of Swelling of Elastomers Monitored by DSC Measurements. J. Phys. Chem. B 2003,107,12884-12890. 

The present experiment is based on the rapid swelling of elastomers by organic solvents. Application of the Flory-Rehner equation yields the number of active network chain segments per unit volume, a measure of the extent of vulcanization (C1,C2). 

Since model networks have known values of Me, they are also extremely useful for clarifying aspects of the equilibrium swelling of elastomers The interpretation of such results utilizes the very recent theory of Flory in which the extent to which the deformation is non-affine depends on the looseness with which the cross-links are embedded in the network structure. This depends in turn on both the structure of the network and its degree of equilibrium swelling. In this case, comparisons between theory and experiment are most conveniently carried out in terms of the equation ... 

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