الملخص

This work studies the gradient energy coefficient ( ) which has the main function in extracting the properties of the polymer, starting from the Simha-Somcynsky theory (SS) that describes the thermodynamic properties of both low and high molecular weights in terms of occupied site fraction (y). Cahn-Hilliard (CH) theory which clarifies the free energy profile of polymer surfaces or interfaces has been also adopted in this study. To gain accurate results, these two theories have been combined with that of Freed Bawendi, which gives the architecture structure for the polymers. Ultimately, the conjunction of these theories produces important properties of polymers such as; the molecular weight, surface tension, the gradient energy coefficient. This study has been performed in the temperature range (313 -473) K and up to about (150) Mpa of pressure according to the international condition of LaGrange for polymers. The success of our study can be clearly seen in the minimum and maximum deviations in (0.036) and (0.128) respectively, while the exact value of gradient energy coefficient has been proved in the high molecular weight polymers as in (PEG 18500). The gradient energy coefficient and the reduced surface tension are directly proportional to molecular weight, while the gradient energy coefficient is inversely proportional to both hole fraction and temperature. The study has been accurately proved by the obtained results and data given in the graphs.