Development of sustainable cellulose-based composite of polypropylene reinforced by recycled microfibrillar poly (ethylene terephthalate)

Sustainable composites based on blends from polypropylene (PP) and recycled polyethylene terephthalate (RPET) and wood flour (WF) were prepared under industry-relevant conditions by melt extrusion, followed by continuous drawing through spinnerets. Maleic anhydride grafted polypropylene (PP-g-MA) was employed to improve the compatibility between matrix and WF. The effects of incorporation of WF and RPET microstructure on the morphological features, rheological measurements, and mechanical properties were investigated. The drawing process converted elliptical RPET phase into highly oriented microfibrillar structure, as characterized by means of scanning electron microscopy (SEM). The highly oriented blend (HOB) represented nonterminal behavior due to the presence of physical networks and enhanced surface area of microfibers for chemical interactions. The tensile strength of neat PP increased by the addition of WF and the existence of microfibrillar RPET phase, whereas the microstructure of RPET had more pronounce effect. The tensile strength and elastic modulus of PP reinforced by WF and oriented RPET improved by 65% and 92%, respectively, demonstrating the high potential of this environmental-friendly reinforcement method to intensify the mechanical properties of PP.