Confinement of iPP crystallites within mesoporous SBA-15 channels in extruded iPP-SBA-15 nanocomposites studied by Small Angle X-ray scattering

The main objective of this research is the study of different nanocomposites based on isotactic polypropylene (iPP) and mesoporous SBA-15 silica prepared by melt extrusion, analyzing the possible effect of this filler on the polymorphic behavior of iPP and the eventual observation of confinement effects. Thus, simultaneous Small Angle X-ray Scattering/Wide Angle X-ray Diffraction (SAXS/WAXD) synchrotron experiments at variable temperature have been performed on several iPP nanocomposites with different contents of SBA-15 mesoporous particles. Real-time variable-temperature SAXS measurements turned out a very useful tool to analyze the confinement of iPP crystallites within SBA-15 channels, and also to determine the most probable long spacing of chains located outside the SBA-15 nanospaces. Importance of these structural features is assessed by changes in the mechanical response of the final materials, finding that the presence of mesoporous particles leads to a reinforcing effect and contribute to improve the final dimensional stabilityThe financial support from project MAT2016-79869-C2-1-P (AEI/ FEDER, UE) is greatly acknowledged. Ms. R Barranco-García also thanks her pre-doctoral funding (BES-2014-070972) associated with the MINECO (MAT2013-47972-C2-1-P) project. The synchrotron experiments were performed at beamline BL11-NCD at ALBA Synchrotron Light Facility with the collaboration of ALBA staff. Authors are grateful for the funding received to perform these measurements. Authors thank to Prof. V. Lorenzo his help in the indentation measurements.Peer reviewe