Electrospun elastic acrylonitrile butadiene copolymer fibers

Abstract

Abstract Nitrile rubber (NBR) is an unsaturated copolymer of acrylonitrile and butadiene. Due to its excellent oil-resistance, NBR products are widely used such as in the automotive and aerospace industries. This paper discusses the fabrication of acrylonitrile butadiene copolymer fibers via electrospinning. A transition from electrospray to electrospinning mechanism was observed and investigated by varying the solution composition. Diameter distributions and average diameters of the electrospun fibers from solutions of various copolymer weight concentrations were determined and compared. Water contact angles of both raw material and electrospun fiber mats were measured. Results indicated that the copolymer material was intrinsically hydrophobic, and the electrospun fiber mats showed higher hydrophobicity due to increased surface roughness. These properties were found to be strongly dependent upon the solution concentration. As the solution concentration increased, average fiber diameter increased and water contact angle decreased. Fiber mats of three different basis weights prepared from solutions of 5% copolymer concentration were prepared. Some of the mats were rolled into yarns. The flat mats and yarns were tested for uniaxial tensile strength to obtain data on their stress-strain performance. Comparison the stress-stain data for the flat mats and yarns showed similar properties. Evaluations of the performances of the fiber mats and yarns accounted for the fiber mat basis weights (mass of fibers per area of mat) and mat porosities through application of an idealized parallel fiber mat model. For small strains the stress-strain curves followed similar paths, but at large strains the paths deviated as fiber-fiber bonds slipped or fibers ruptured. For different basis weights, maximum tensile strengths of the flat mats and yarns were close, but slightly varied due to the more complex fiber structures compared to the idealized model. The yarns held larger stresses before rupture and possessed higher maximum tensile strengths than the flat mats attributed to the lower porosity of the yarns and additional bonds between fiber layers that are absent in the flat mats.