INVESTIGADORES
MARCOVICH norma Esther
artículos
Título:
STUDY OF NANO-REINFORCED SHAPE MEMORY POLYMERS PROCESSED BY CASTING AND EXTRUSION
Autor/es:
TARA RICHARDSON; MIRNA A. MOSIEWICKI; CIHAN UZUNPINAR; NORMA E. MARCOVICH; MIRTA I. ARANGUREN; FATMA KILINC-BALCI; ROY M. BROUGHTON, JR.; MARIA L. AUAD
Revista:
POLYMER COMPOSITES
Editorial:
JOHN WILEY & SONS INC
Referencias:
Año: 2011 vol. 32 p. 455 - 463
ISSN:
0272-8397
Resumen:
Multi-walled carbon nanotubes (CNTs) and cellulose nanofibers (CNFs) reinforced shape memory polyurethane (PU) composite fibers and films have been fabricated via extrusion and casting methods. Cellulose nanofibers were obtained through acid hydrolysis of microcrystalline cellulose. This treatment aided in achieving stable suspensions of cellulose crystals in dimethylformamide (DMF), for subsequent incorporation into the shape memory matrix. CNTs were covalent functionalized with carboxyl groups (MWCN-COOH) and 4,4?-methylenebis (phenylisocyanate) (MDI) (MWCNT-MDI) in order to improve the dispersion efficiency between the CNT and the polyurethane. Significant improvement in tensile modulus and strength were achieved by incorporating both fillers up to 1 wt% without sacrificing the elongation at break. Electron microscopy was used to investigate the degree of dispersion and fracture surfaces of the composite fibers and films. The effects of the filler (type and concentration) on the degree of crystallinity and thermal properties of the hard and soft segments that form the PU sample were studied by calorimetry. Overall, results indicated that the homogeneous dispersion of nanotubes and cellulose throughout the PU matrix and the strong interfacial adhesion between nanotubes and/or cellulose and the matrix are responsible for the enhancement of mechanical and shape memory properties of the composites.