Showing papers in "Clay science in 2016"

Effect of maleic anhydride-grafted polypropylene on the morphological and mechanical properties of clay/polypropylene nanocomposites

Abstract: The effect of maleic anhydride (MAH)-grafted polypropylene (PP) on the structure and mechanical properties of PP nanocomposites was examined using identical experimental conditions. MAH-grafted PP was prepared with various concentrations of MAH, using tert-butylbenzoxylate as the initiator in xylene at 140°C. The MAH grafting ratio of the resulting three samples was estimated by H-NMR measurement. The MAH content were controlled to PP/MAH = 100/0.1 to 100/0.5 by mass ratio. An organically modified clay was melt-kneaded with PP and the MAH-grafted PP in a twin-screw kneader. The exfoliation of the clay layers in the polymer matrix was fairly advanced with the grafting ratio. Depending upon the morphology change, the tensile modulus of the nanocomposite is increased by a factor of roughly 1.5 compared to that of the nonreinforced polymer. Dynamic mechanical analyses (DMA) were conducted to compare the rheological properties of PP and high MAH-grafted PP systems. The incorporation of clay layers in the MAH-grafted PP led to a considerable increase in the storage modulus (E’) and a shift to higher temperatures in the α relaxation peaks for polymer.

Qcm studies on adsorption of water molecules on a single-layered clay film

Abstract: the adsorption of water molecules on the surface of a clay mineral was studied by means of quartz crystal microbalance (QCM) measurements. For the purpose, an ultra-thin film of exfoliated montmorillonite sheets was prepared by the modified Langmuir method. On introducing a nitrogen gas at various humidity, the adsorption and desorption processes of water molecules on a clay film were monitored in terms of mass change. The adsorbed amount of water molecules was compared among the following four films: (F1) a single-layered clay-amphiphile hybrid film, (F2) a single layered clay film, (F3) a double layered clay-amphiphile hybrid film and (F4) a double-layered clay film. The nature of adsorbed water molecules was investigated by comparing the IR spectra between F1 and a cast film.

Study of different monitorillonites as “support-activators” for metallocene-catalyzed propylene polymerization

Abstract: Three different kinds of montmorillonites (Benclay SL, Benclay KK, and Kunipia F) were evaluated as “Support-Activators” for metallocene-catalyzed propylene polymerization. The respective clay materials were acid-treated to alter their physico-chemical properties, and used for the preparation of metallocene catalysts. The catalyst systems were subsequently characterized and their efficacy in facilitating the polymerization of propylene was evaluated. It was observed that polymerization activities were specifically influenced by the kind of clay mineral used. Based on our study, the level of catalytic activity is proportionally related to the surface areas of the small-size pores (pore diameter<6 nm), where strong acid sites are present.