碳纳米管增强聚合物纤维增强机理(英文).ppt

* Adv. Funct. Mater. 2011, 21, 364–371 Reading Report Outline Innovation and inspiration Result and discussion Experimental Conclusion Introduction Introduction Very few studies have reported measurements of the mechanical properties of polymer-nanotube composite ?bers as a function of nanotube content Krenchel extended Cox’s original model to show that the modulus and strength of composites ?lled with rodlike ?llers scales linearly withη0 , However to our knowledge, it has never been demonstrated experimentally that this scaling holds for a range of orientations (i.e., a range of η0 values) for any nanocomposite. it should be possible, not only to quantitatively examine the Cox-Krenchel equation, but to demonstrate the production of relatively stiff, strong ?bers. Experimental Materials Methods Puri?ed SWNTs (HiPCO, Unidym), polyvinyalcohol (J. T. Baker, Mw= 77,000–79,000 g mol ?1, 99–99.8% hydrolysed) and the surfactant sodium cholate (Aldrich) NT sodium cholate deionised water sonic tip processor centrifuged Polyvinylalcohol solution spinning drawing dried test For perfectly aligned ?bers (η0=1) prepared with long nanotubes (ηlY=1), dY/dVf=YNT, which has a maximum value of 1000 GPa the mechanical properties of composite ?bers are limited by the nanotube length, the strength of the polymer-nanotube interface and the degree of nanotube alignment. Here the ?bers have dY/dVf～600 GPa and dσB/dVf～7GPa for DR40% S=0 for random orientation to S=1 for perfect axial alignment In the ideal case,YEff should be identical to dY/dVf For undrawn ?bers and for DR≤22%, dY/dVf =YEff. However, for higher draw ratios, dY/dVf YEff XRD YNT=480±40 GPa or about half the expected value The values of dσB/dVf achieved, even for the drawn ?bers are relatively low;7GPa compared to a potential value of 50–130 GPa τ=40±4MPa. This is very close to the known shear yield strength of PVA (41 MPa) *