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Handbook of Solvents - George Wypych - ChemTech - Ventech!

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5.1 Solubility parameters 249<br />

mediate position between solubility parameters <strong>of</strong> solvents. Assumption is made that the<br />

maximum polymer swelling occurs when the solubility parameters <strong>of</strong> the solvent mixture<br />

and polymer are equal. This is the case when the solubility parameter <strong>of</strong> polymer is lower<br />

than the solubility parameter <strong>of</strong> the primary solvent and the solubility parameter <strong>of</strong> the secondary<br />

solvent is higher. The dependence <strong>of</strong> the swelling ratio on the composition <strong>of</strong> solvent<br />

mixture has a maximum (see Figure 5.1.2). Such mixed solvents are called symmetric<br />

liquids. The reliability <strong>of</strong> the method is examined by a narrow interval <strong>of</strong> change <strong>of</strong> the solubility<br />

parameter <strong>of</strong> a binary solvent. The data obtained by this method in various mixtures<br />

differ by no more than 1.5% with the data obtained by other methods. Examples <strong>of</strong> results<br />

are given in Tables 5.1.2, 5.1.3.<br />

Table 5.1.2. Values <strong>of</strong> solubility parameters for crosslinked elastomers from swelling<br />

in symmetric liquids. [Adapted, by permission, from V.V. Tereshatov, V.Yu. Senichev,<br />

A.I. Gemuev, Vysokomol. soed., B32, 412 (1990).]<br />

H<br />

Elastomer Symmetric liquids ϕ2 at Qmax<br />

Polyether urethane<br />

Ethylene-propylene rubber<br />

Butadiene-nitrile rubber<br />

Polyester-urethane<br />

Toluene( 1) - acetone (2)<br />

Cyclohexane (1) -acetone (2)<br />

Hexane (1) - benzene (2)<br />

Toluene (1) - acetone (2)<br />

Ethyl acetate (1) - acetone (2)<br />

Benzene (1) - acetone (1)<br />

Toluene (1) - acetone (2)<br />

o-Xylene (1) - Butanol -1(2)<br />

0.11<br />

0.49<br />

0.38<br />

0.32<br />

0.22<br />

0.27<br />

0.62<br />

0.21<br />

δ p , (MJ/m 3 ) 1/2<br />

18.4<br />

18.2<br />

16.2<br />

18.9<br />

19.1<br />

19.1<br />

19.6<br />

19.5<br />

Butyl rubber Octane (1) - benzene (2) 0.26 16.1<br />

Table 5.1.3. Values <strong>of</strong> solubility parameters <strong>of</strong> crosslinked elastomers from swelling<br />

in individual solvents and symmetric liquids. [Adapted, by permission, from<br />

V.V. Tereshatov, V.Yu. Senichev, A.I. Gemuev, Vysokomol. soed., B32, 412 (1990).]<br />

Symmetric<br />

Individual solvents<br />

Elastomer<br />

liquids Gee method<br />

(MJ/m<br />

Bristow-Watson method<br />

3 ) 1/2<br />

Polyether-urethane 18.3±0.1 17.8, 18.4, 19.4 19.2<br />

Ethylene-propylene rubber 16.2 16.1-16.4 -<br />

Butadiene-nitrile rubber 19.0±0.1 18.9-19.4 18.7<br />

Polyester-urethane 19.5-19.6 19.3, 19.9 19.5<br />

Butyl rubber 16.1 15.9-16.6 14.9<br />

The calculations were made using equation:<br />

2<br />

2 [ 1 ( 1 1) 2 1 Δ H / V12]<br />

δ = δ = δ − ϕ′′ + δ ϕ′′<br />

−<br />

p mix mix<br />

12 /<br />

[5.1.18]

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