Composites of carbon nanofibers and thermoplastic polyurethanes with shape-memory properties prepared by chaotic mixing artículo Académico uri icon

abstracto

  • Composites of carbon nanofibers (CNFs), oxidized carbon nanofibers (ox-CNFs), and shape-memory thermoplastic polyurethane (TPU) were prepared in a chaotic mixer and their shape-memory properties evaluated. The polymer was synthesized from 4,40-diphenylmethane diisocyanate, 1,4′butanediol chain extender, and semicrystalline poly(ε-caprolactone) diol soft segments. The shape-memory action was triggered by both conductive and resistive heating. It was found that soft segment crystallinity and mechanical reinforcement by nanofibers produced competing effects on shapememory properties. A large reduction in soft segment crystallinity in the presence of CNF and stronger mechanical reinforcement by well-dispersed ox-CNF determined the shape-memory properties of the respective composites. It was found that the maximum nshape recovery force, respectively, 3 and 4 MPa, was obtained in the cases of 5 and 1 wt% CNF and ox-CNF, respectively, compared with ∼1.8 MPa for unfilled TPU. The degree of soft segment and hard segment phase separation and thermal stability of the composites were analyzed. © 2009 Society of Plastics Engineers.

fecha de publicación

  • 2009