title: Tuning the mechanical properties of composites from elastomeric to rigid thermoplastic by controlled addition of carbon nanotubes.
abstract: A commercial thermoplastic polyurethane is identified for which the addition of nanotubes dramatically improves its mechanical properties. Increasing the nanotube content from 0% to 40% results in an increase in modulus, Y, (0.4-2.2 GPa) and stress at 3% strain, σ(ϵ = 3%) , (10-50 MPa), no significant change in ultimate tensile strength, σ(B) , (≈50 MPa) and decreases in strain at break, ϵ(B) , (555-3%) and toughness, T, (177-1 MJ m(-3) ). This variation in properties spans the range from compliant and ductile, like an elastomer, at low mass fractions to stiff and brittle, like a rigid thermoplastic, at high nanotube content. For mid-range nanotube contents (≈15%) the material behaves like a rigid thermoplastic with large ductility: Y = 1.5 GPa, σ(ϵ = 3%) = 36 MPa, σ(B) = 55 MPa, ϵ(B) = 100% and T = 50 MJ m(-3) . Analysis suggests that soft polyurethane segments are immobilized by adsorption onto the nanotubes, resulting in large changes in mechanical properties.
authors.affiliation: School of Physics, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Umar
authors.initials: U
authors.lastname: Khan
authors.forename: Peter
authors.initials: P
authors.lastname: May
authors.forename: Arlene
authors.initials: A
authors.lastname: O'Neill
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Vilatela
authors.forename: Alan H
authors.initials: AH
authors.lastname: Windle
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Coleman
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D055119:Elastic Modulus; D020724:Elastomers / Q000737:chemistry*; D006371:Helium / Q000737:chemistry; D055595:Mechanical Phenomena; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D013314:Stress, Mechanical; D013696:Temperature; D014783:Viscosity
chemical_list: D003432:Cross-Linking Reagents; D020724:Elastomers; D037742:Nanotubes, Carbon; D011140:Polyurethanes; D006371:Helium