CONICET | Buscador de Institutos y Recursos Humanos

Presently we discuss the effect of the o-MMT on the morphological, rheological and tribological properties of PP/PPg/o-MMT nanocomposites. The PP (Petroquí-mica Cuyo, Mw=330,000 g/mol), PPg (Polybond 3200, Mw=120,000 g/mol, 1wt% of maleic anhydride) and the mixing conditions (15 min in a Brabender Plastograph at 185°C and 50 rpm under nitrogen atmosphere) were the same in all mixings. All the composites have 5 wt% of o-MMT and 15 wt% of PPg. X-ray diffraction and scanning electron microscopy were used to obtain the structural characteristics and interlayer spacing of clays and composites and the micro-morphology of PNCs. The elastic and viscous moduli of all polymers were measured in a rotational rheometer using small amplitude oscillatory shear flow between parallel plates under nitrogen atmosphere. The analyzed characteristics and rheological behavior of PP/PPg/o-MMT strongly depend on the nature of the intercalant used in the o-MMT. This is because the stability of the clay during processing/characterization and the value of the binding energy ?clay-surfactant? relative to those between clay and polymers are determined by the nature of the surfactant. Moreover, the binding energies, together with the size and shape of the intercalant molecules, determine the organization of these molecules between the platelets (and, consequently, the basal spacing) and the possibility for the PPg molecules to squeeze inside the interlayer region. However, the phase structure of the hybrids is not only determined by the components and processing conditions but also by the post processing annealing stage at a temperature close to the initial decomposition temperature of the OMMTs. It has been observed that during the annealing the intercalation/exfoliation process continues producing materials that have stable phase-structure with larger degree of interactions between filler particles.

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