Influence of Aluminum Oxide Nanoparticles on Formation of the Structure and Mechanical Properties of Microfibrillar Composites

The effect of nanosize alumina (Al2O3) concentration on the morphology and mechanical properties of microfibrillar composites obtained by processing the thermodynamically incompatible polypropylene/ copolyamide (PP/CPA) blend was studied. It was established that composite monofilaments exhibited a selfreinforcing effect due to the in situ formation of PP fibrils (microfibers) in the CPA matrix. The tensile strength and the initial elastic modulus of the filaments studied depended on their structure and correlated with dimensional characteristics of the disperse phase component. It is shown that the introduction of Al2O3 nanoparticles in an amount of (0.1-3.0) wt.% allows one to adjust the structure formation process of the dispersed phase component to obtain composites with a thin homogeneous morphology. The maximum performance was achieved for filaments formed from a composition containing 1.0 wt.% alumina. In this case, microfibers were the predominant type of structure, and their diameters were minimum. The increasing ability of the jets of nanofilled melts of PP/CPA blends to the longitudinal deformation was due to the formation of a more perfect microfibrillar structure during extrusion. This makes it possible to obtain filaments from such blends on already existing extrusion equipment.