The structure and properties of polymer composite fibers based on poly(vinyl alcohol) and nanodiamond of detonation synthesis

The structure and properties of the oriented poly(vinyl alcohol) fibers modified with nanodiamonds (NDs) and nanodiamond soot (NS) of detonation synthesis were investigated by wide-angle and small-angle X-ray scattering methods, as well as by electron microscopy and mechanical testing methods. It was shown that the introduced nanodiamond soot particles were dispersed within the polymer matrix while maintaining a high dispersion level without aggregation. The NS treated with ultrasound was found to be a more effective modifier of the mechanical properties of the oriented fibers than untreated soot and NDs. The maximum increase in the longitudinal elastic modulus over nonmodified fibers (from 30 GPa up to 45 GPa) and in the energy stored by oriented fiber modified with NS upon breaking (from 3 up to 6 J/g) was obtained at a small (1% by volume) soot content, which is technologically attractive. The values of the adhesive strength of the soot modified with ND (1%) with volume poly(vinyl alcohol) fibers in the epoxy matrix were measured, and the maximally achieved value (42 MPa) was higher than the adhesive strength of the nonmodified fibers and comparable with the value of the reference sample (steel wire (57 MPa)).