Abstract
High-impact polystyrene (HIPS) nanocomposites with organically modified montmorillonite (MMT) via free-radical bulk polymerization techniques were synthesized to investigate the effect of organophilic clay on various properties, such as thermal, rheological and mechanical properties. The X-ray diffraction peak of the nanocomposites prepared with a benzyldimethyl hydrogenatedtallow MMT was confirmed to shift to lower angle, indicating the intercalation of polymer chains into silicate layers. In special, the organically modified MMT that was ion-exchanged with a surfactant having a reactive group, dimethyloctadecylvinylbenzyl ammonium bromide, showed unique dispersion capabilities of silicate layer showing exfoliated morphology when prepared with styrene polymerization. With clay introduction, the rubber-phase particle size and size distribution of the nanocomposites increased and widened, respectively, compared with their counterparts prepared without clay. The nanocomposites showed improved thermal properties from a thermogravimetric analysis. Rheological properties such as the complex viscosity and the storage modulus increased with increasing organophilic MMT contents. Even in the addition of 1-3% of the organoclay, the storage modulus increased substantially and the slope decreased. Mechanical properties were also evaluated and some properties were superior to conventional HIPS. Impact strength was inferior, but the nanocomposites with minimal loss of impact properties could be prepared by changing the polymerization procedure.
