DETERMINATION OF EXCHANGE ENTHALPY AND ENTROPY PARAMETERS OF POLY(DIMETHYL SILOXANE) WITH SOME N-ALKANES BY INVERSE GAS-CHROMATOGRAPHY

The total interaction parameter at infinitely high polymer concentrati on, chi(t)(infinity), and the effective exchange energy parameter, <(X )over bar (12)>, of poly(dimethyl siloxane) with n-pentane, n-hexane, n-heptane and n-nonane were determined around room temperature using t he inverse gas chromatography technique. The values of chi(t)(infinity ) are in agreement with corresponding literature values. The exchange enthalpy X(12) and entropy, Q(12), parameters were determined at the s ame temperature. The X(12) parameters increase with the carbon number of the n-alkanes, while their temperature dependence is almost negligi ble. The Q(12) parameters are approximately independent of temperature and carbon number of the n-alkanes.