Experimental studies of the mechanical characteristics of composite polymer materials based on polypropylene doped with carbon nanotubes

Research objective. This work considers the issues of using carbon nanotubes as fillers in order to improve the strength properties of polymer materials based on polypropylene, which are used in various industries, oil and gas production, metallurgy, electric power engineering, etc. Methods. A method for creating a new polymer composite material based on polypropylene with the addition of carbon nanotubes has been developed. Experimental tests of the strength of prototypes made of the "polypropylene-carbon nanotubes" composite were conducted in accordance with GOST 25.601-80 "Calculations and Tests for Strength". Results. In the course of experimental studies, it was found that ultrasonic exposure of carbon nanotubes with a properly selected solvent and exposure conditions is an important condition for using CNTs as a nano-additive. To obtain a composite granular polymer material by introducing carbon nanotubes, it is most advisable to use a twin-screw extruder with pre-selected temperature regimes in each heating zone and the speed of rotation of the screws. It has been established that the introduction of carbon nanotubes in microquantities (0.2–0.4 wt. %) into the polymer matrix leads to an increase in the maximum allowable load to ~0.03–0.05 kN, the plastic deformation coefficient ~2.2–7.1% and the tensile strength ~1–2.5 N/mm2. Conclusion. The results obtained allow us to conclude that the use of carbon nanotubes as nanoadditives in the polymer matrix of polypropylene allows us to create special polymers with unique properties without significantly increasing the cost of their production. In addition, the control of the percentage of CNTs allows us to design custom materials with precise control of their properties.