Recycled polypropylene matrix nanocomposites reinforced with silane functionalized geopolymer concrete waste

The objective of this work is the processing of recycled polypropylene (rPP) matrix and geopolymer concrete waste (GCW) to develop novel sustainable nanocomposites for engineering applications. Specimens of these nanocomposites were produced from GCW added in proportions of 20, 40 and 50 wt% to rPP. The pulverized waste, with nanometric particles, was used as neat, GCW, or as surface functionalized with vinyl trimethoxy silane (GCW/VTS). Separately, both GCW and GCW/VTS were mixed with rPP by means of extrusion reactive extrusion and injection processing before final molding of specimens. The composition microstructure, thermal stability and tensile properties of the specimens were studied by wide angle X-ray diffraction, thermogravimetry, differential scanning calorimetry, water absorption, tensile tests, and field emission gun scanning electron microscopy with energy dispersive spectroscopy. The main findings were an increased thermal stability and enhanced elastic modulus with incorporation of both GCW and GCW/VTS. A high degree of interaction between GCW filler and rPP matrix, including the first time observed mechanism of PP nanofilaments adhesion, is responsible for a negligible water absorption. A decrease in the crystallinity suggests an interference of GCW in the rPP arrangement of macromolecular chains. (C) 2020 Published by Elsevier B.V.