Nanocomposites and Nanomaterials

Paramagnetic and tribological properties of nanocomposites based on BCP-7 copolymer and carbon fibers as fillers
Grashchenkova M.A.1, Tomina A-M.V.1, Krasnovyd S.V.2, Konchits A.A.2, Shanina B.D.2
1 Department of Condensed Matter Physics, Dniprovsk State Technical University.
Dneprostroevskaya str., 2, Kamenskoe- 51918, Ukraine
2 Department of Optics and Spectroscopy, Institute of Semiconductor Physics of the NAS of Ukraine. Prospect Nauki, 41, Kyiv-03028, Ukraine. 
E-mail: sergkrasnovyd88@gmail.com

Carbon fibers (CFs), due to their excellent mechanical properties, are often used as fillers for the creation of composite materials (carbon fiber reinforced plastics) for tribological purposes [1]. In this work, the effect of low-modulus CFs Uglen as a filler (10 ÷ 40 wt.%) on the magnetic and tribological properties of the thermoplastic block copolymer sulfuryl BCP-7 is considered. 
Based on experiments on electron paramagnetic resonance (EPR), it was found that Uglen CFs contain a high concentration of paramagnetic defects - carbon dangling bonds, characterized by g-factor g = 2.0034. Due to the developed Uglen surface, the EPR linewidth Hpp increases from ~5 G in vacuum to 65 G in the air due to interaction between CFs and paramagnetic molecular oxygen O2. The value of Hpp increases up to 130 G in the composite, depending on the filler concentration, which indicates the interaction of the polymer matrix with the filler.
The processing of BCP-7 and carbon plastics based on it into block products was carried out by the method of compression pressing. It was found that under conditions of friction without lubrication, the produced composites surpass the base polymer in wear resistance and coefficient of friction by 18.9 and 1.6 times, respectively. The developed composite surpasses the materials known on the market, such as Caprolon B, polyamide PA 6-210/310, and polyamide PA 12-L, in terms of the set of technical properties. Thus, BCP-7 plastics, reinforced with Uglen, can be recommended for the manufacture of plain bearings operating in conditions of friction without lubrication.

1.	Konchits A., Yeriomina Ye., Tomina A.-M., Lysenko O, Krasnovyd S., Morozov O. Advanced Polymer Composites for Use on the Earth and in Space. In: Nanotechnology in Space. Pan Stanford Publ. - 2021, P. 71-119.