The swelling of alkyd resin and epoxy ester resin networks

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  • アルキド樹脂およびエポキシエステル樹脂皮膜の膨潤
  • アルキド ジュシ オヨビ エポキシエステル ジュシ ヒマク ノ ボウジュン

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The three-dimenrional networks, such as in alkyd resin and epoxy ester rerin films, absorbs solvent, the swelling advancing, the molecular chain between networks stretches the configuration, the contracting force of rubber like elasticity withstands against the swelling.<BR>As the swelling advances, the contracting force incresaes and the swelling force decreases. Two opposing forces thus created reach balanced equilibria at the last step. In this case, the mutual action between the polymer and the solvent can be characterized by the value μ. The value μ can be found from measurement of the osmotic pressure in case of polymer solution and of the degree of swelling in case of cross-linked polymer and the following equation has been proposed by Flory : <BR>μ=-ln(1-υ2g)-υ2g2V1/Mc((υ2g1/32g/2)/υ22g<BR>Where ;<BR>υ2g is volumetric fraction (1/Qv) of the polymer at the swelling of equilibrium.<BR>ρ2 and ρ1 are densities of the polymer and the solvent.<BR>V1 is molecular volume of the solvent.<BR>Mc is molecular weight between the cross-linkings of the polymer.<BR>μ values were measured at a few selected temperatures on 10 kinds of alkyd resin which Mc differs and 5 kinds of epoxy esters which oil length and the molecular weight differ. The results are as follows.<BR>(1) The degree of swelling of alkyd resin film lowers according to the order of ketones>esters>aromatic hydrocarbons>alcohols, and insteadly the value of μ increases. The value of μ for ketone, esters, aromatic hydrocarbons and alcohols are 0.5-0.6,0.6-0.7,0.7-0.9 and 1.0-1.3, respectively.<BR>(2) As for the swelling of alkyd resin film measured by binary solvent of benzene-acetone system, a solvent composition which shows maximum degree of swelling and minimum value of μ exists. The solubiltyparameter (δ2) of resin can be found from the maximum value of Qv and from the minimum value of μ and the δ2 decreases according to the decrease in Mc.<BR>(3) The degree of swelling of alkyd resin and of epoxy resin ester decreases according to the decrease in Mc. When the values of Mc are identical, the degree of swelling for th epoxy resin ester containing p-t-butyl benzoic acid is less than that of the same type resin which does not contain the acid.<BR>(4) The temperature-dependency of μ increases with the increase of the μ value. The μ value for MEK, being the strongest swelling power, is equal to the minimum value of μ of binary solvent of benzene-acetone system, and its temperature-dependency is negligible.

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