|M.Sc Student||Adibekian Asmik|
|Subject||Study of the Morphological and Mechanical Properties of|
S-E/B-S Fibers with Embedded Carbon Nanotubes
|Department||Department of Mechanical Engineering||Supervisor||Professor Eyal Zussman|
|Full Thesis text|
Composite materials are widely used in the aviation, automotive industry, and advanced sporting goods due to their high strength and toughness, lightness, high thermal conductivity and electrical insulation, high corrosion resistance, and ability to sustain damage. In the fast growing field of nanotechnology, polymer (nano)composites have become a prominent area of current research and development. A nanocomposite is a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nanometers (nm), or structures having nano-scale repeat distances between the different phases that make up the material. Nanocomposites differ from conventional composite materials due to the exceptionally high surface to volume ratio of the reinforcing phase and/or its exceptionally high aspect ratio. The reinforcing material can be made up of particles (e.g., minerals), sheets (e.g., exfoliated clay stacks) or fibers (e.g., carbon nanotubes or electrospun fibers). The area of the interface between the matrix and reinforcement phase(s) is typically an order of magnitude greater than for conventional composite materials.
In the present study we focus on the development of multi wall carbon nanotubes (MWCNTs) reinforced composite fibers composed of elastomeric tri-block copolymer styrene-ethylene/butylene-styrene (S-E/B-S). CNTs are used to enhance the shear strength properties of S-E/B-S/UHMWPE laminate due to their high stiffness, toughness and tensile strength. The composite fibers are manufactured by electrospinning of suspension of polymer and low concentration of MWCNTs (~ 1wt.%). The fibers are deposit between laminated ultra-high-molecular-weight polyethylene (UHMWPE) fabrics. For production of composite laminates, hot compressing molding method was applied.
WAXS analysis shows enhanced crystal size by ~150% in fibers with MWCNTs compared to the fibers without MWCNTs. No changes were observed in the lamellar morphology of the composite fibers compared to the film analyzed by SAXS. DMA analysis of polymer fiber embedded with 1wt.% MWCNTs shows improvement of ~15% in fiber ultimate tensile strength and improvement of ~242% in fiber Young’s modulus in comparison with fibers without MWCNTs. Moreover, lap shear test performed on the laminates of UHMWPE reinforced with S-E/B-S and MWCNTs composite fibers shows improvement of 35% in strength to failure indicating that S-E/B-S fibers interface can be considered as an essential parameter influencing the in-plane shear.