سال انتشار: ۱۳۹۰

محل انتشار: کنفرانس بین المللی فرآورش پلیمرها

تعداد صفحات: ۴

نویسنده(ها):

m Mazidi – School of Chemical Engineering, Iran University of Science and Technology (IUST), P.O. Box 16844–۱۳۱۱۴, Tehran, Iran

چکیده:

Poly (styrene-co-ethylhexylacrylate) latex particles containing various contents of carboxylic and hydroxyl functional groups were synthesized in the presence of anionic and nonionic surfactants, mainly sodium dodecyl sulfate (SDS) and Igepal, respectively. Surface properties of polymeric latexes were examined by contact angle measurements. The results showed that increasing the functional group content (1-6%) of polymeric latexes result in increasing the polar component of surface energy (γ p) and thereby total surface energy (γ total) increases. Meanwhile, the mean-field model of polymer melt intercalation in organically-modified layered silicates (OLS) originally developed by Vaia and Giannelis [1, 2] was applied for polymeric latexes synthesized in various conditions. In this model, the Helmholtz free energy change caused by the interaction of polymer, surfactant and clay is the strongest factor in determining the equilibrium structure of the nanocomposite system. Therefore, the Helmholtz free energy was calculated to study the possibility of melt intercalation of polymeric latexes in various nanoclays include as-received Cloisite®۳۰B, Cloisite®۱۵A and Na-MMT modified with aminoundecanoic acid (AUA) and Methacryloxyethyltrimethylammonium chloride (MAETAC). Helmholtz free energy below zero favors the polymer melt intercalation process, while free energies greater than zero indicates incompatibility of polymer matrix and organosilicate layers. The results revealed that increasing the percentage of both carboxylic and hydroxyl functional groups on co-monomer results in decreasing the Helmholtz free energy. Consequently, copolymer synthesized without any functional group in presence of anionic surfactant (SDS) had the lowest Helmholtz free energy. It seems that in-situ polymerization may be applied as an alternative method to obtain polymer/clay nanocomposites with presumably exfoliated structures