Effect of iPP Molecular Weight on its Confinement within Mesoporous SBA-15 Silica in Extruded iPP/SBA-15 Nanocomposites

ROSA BARRANCO GARCÍA; JOSÉ GÓMEZ ELVIRA; JORGE A. RESSIA; LIDIA MARÍA QUINZANI; ENRIQUE M. VALLÉS; ENRIQUE PÉREZ; MARÍA LUISA CERRADA

MICROPOROUS AND MESOPOROUS MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020 vol. 294 p. 1 - 10

1387-1811

Different nanocompositesbased on two isotactic polypropylenes (iPP) and mesoporous SBA-15 silica havebeen attained by melt extrusion as an attempt to understand the influence ofaverage molecular weight in the rheological behavior, morphological andcrystalline features and in the final properties (thermal stability andmechanical response) as well as in the capability of incorporating iPP chains withinthe nanometric SBA-15 pores. Closeness to rheological percolation and asignificant increase of viscosity are observed as SBA-15 content is raised,this effect being more evident for the materials prepared from the iPP with thelowest molecular weight. These latest composites also shift to lower temperaturestheir maximum degradation under inert atmosphere, but keep rather unchangeddecomposition behavior in oxidant conditions. No considerable changes are foundwith molecular weight in their morphological characteristics, nor in the typeof iPP polymorph developed. The inclusion of iPP chains in the SBA-15 channelsis, however, significantly different. Differential scanning calorimetryexperiments and real-time variable-temperature Small Angle X-ray Scattering(SAXS) measurements with synchrotron radiation both indicate that largercrystallites are developed within the mesostructure in the materials preparedfrom the iPP with inferior molecular weight. Moreover, the SBA-15 mesoporousparticles exert a reinforcing role in all cases and reduce the deformationcapacity of the ultimate materials as their content is increased.