(217v) Polyolefin-Based Nanocomposites: The Role of Compatibilizer On the Mechanical Properties of WS2 Nanotubes-Reinforced Polypropylene

Polypropylene (PP) is one of the most widely used engineering polyolefins and, therefore, intensive research efforts are underway for tailoring its final properties through the preparation of its nanocomposites. PP-nanocomposites are reported to have an increased thermal stability, better mechanical properties, enhanced barrier and other properties.

 A lot of work is being done for better dispersing nanoparticles in polymer matrices, because the degree of dispersion affects most of the nanocomposite properties. Some routes involve the surface modification of the nanofiller, while another route follows the incorporation of a second polymer into the mixture as a compatibilizer. The second route seems to be the most promising one, since it is easier to be implemented in industrial scale. Several works report the use of maleic-anhydride-grafted polypropylene (PPGMA) for enhancing the dispersion of layered silicates inside the PP matrix.

 In this work, we investigate the role of compatibilizing agent PPGMA on the mechanical properties of WS₂-nanotubes reinforced PP nanocomposites. More specifically, we report the preparation procedure, the structural, thermal and mechanical characterization of polymer nanocomposites based on the ternary blend consisting of PP, PPGMA and WS₂ nanotubes.

 A co-rotating twin-screw micro-extruder/-compounder (MiniLab, Thermo-Haake) was used for dispersing the nanotubes in the polymer blend.  Different mixing conditions were tested to ensure the complete mixing of the two phases (inorganic and organic). The creation of a homogenous mixture was ensured by the stabilization of the screw torque and the melt’s viscosity.

 The hybrid materials produced were examined using Scanning Electron Microscopy (SEM), Scanning Probe Microscopy (SPM) and X-Ray Diffraction (XRD). The mechanical properties were investigated by tensile testing, as well as by Dynamic Mechanical Thermal Analysis (DMTA). The results show that PP/PPGMA blends reinforced with small amounts of WS₂ nanotubes exhibit improved properties compared to similar systems (PP/WS₂ and PPGMA/WS₂) studied by our group.