TY - JOUR
T1 - Strain-induced matrix and droplets anisotropic deformation in liquid crystalline cellulose dispersed liquid crystal films
AU - Filip, Daniela
AU - Costa, Ivo
AU - Figueirinhas, J. L.
AU - Godinho, M. H.
N1 - This work was supported by projects POCI/CTM/56382/2004; POCTI/CTM/ 37435/2002 and by the Portuguese Science Foundation (FCT) through Pluriannual contracts with CENIMAT and CFMC/UL. D. Filip gratefully acknowledges FCT for Grant SFRH/BPD/19722/2004.
PY - 2006
Y1 - 2006
N2 - The present work deals with the preparation of new liquid crystalline cellulose dispersed liquid crystal films (100 μm) using a shearing casting technique. The matrix of the films presents the so-called band texture perpendicular to the shear direction. The nematic low molecular weight liquid crystal is encapsulated in micron and submicron size ellipsoids. The ratio between the lengths of the main axis and the short axis is around 1.23. The main axis is oriented, on average, 28° away from the shear direction. The evolution of the band texture and of the ellipsoidal liquid crystal droplets is investigated by polarizing optical microscopy and light scattering techniques as a function of the strain imposed along and perpendicular to the shear direction. Stretch along shear with strain equal to 0.8 seems to have no effect on the banded structure of the matrix, while the nematic liquid crystal ellipsoids slightly orient the main axis to the stress direction and their shape anisotropy increases by a factor of 2. Deformation in the direction transverse to the shear direction induces a deep change of the polymeric matrix and, at the end, a fibrillar structure is found. The nematic ellipsoids rotate their main axis and align along the stretch direction. Their shape anisotropy evolves from a value of 1.23 to 1 for intermediate deformations with strain equal to 0.5, to a final value of 5 with strain equal to 0.8, in the perpendicular direction.
AB - The present work deals with the preparation of new liquid crystalline cellulose dispersed liquid crystal films (100 μm) using a shearing casting technique. The matrix of the films presents the so-called band texture perpendicular to the shear direction. The nematic low molecular weight liquid crystal is encapsulated in micron and submicron size ellipsoids. The ratio between the lengths of the main axis and the short axis is around 1.23. The main axis is oriented, on average, 28° away from the shear direction. The evolution of the band texture and of the ellipsoidal liquid crystal droplets is investigated by polarizing optical microscopy and light scattering techniques as a function of the strain imposed along and perpendicular to the shear direction. Stretch along shear with strain equal to 0.8 seems to have no effect on the banded structure of the matrix, while the nematic liquid crystal ellipsoids slightly orient the main axis to the stress direction and their shape anisotropy increases by a factor of 2. Deformation in the direction transverse to the shear direction induces a deep change of the polymeric matrix and, at the end, a fibrillar structure is found. The nematic ellipsoids rotate their main axis and align along the stretch direction. Their shape anisotropy evolves from a value of 1.23 to 1 for intermediate deformations with strain equal to 0.5, to a final value of 5 with strain equal to 0.8, in the perpendicular direction.
KW - Band texture
KW - Cellulose liquid crystals
KW - Dispersed liquid crystals
KW - Light scattering
KW - Liquid crystal ellipsoids
KW - Optical microscopy
UR - http://www.scopus.com/inward/record.url?scp=33746051378&partnerID=8YFLogxK
U2 - 10.1163/156855406777408539
DO - 10.1163/156855406777408539
M3 - Conference article
AN - SCOPUS:33746051378
VL - 13
SP - 477
EP - 486
JO - Composite Interfaces
JF - Composite Interfaces
SN - 0927-6440
IS - 4-6
T2 - International Conference on Advances in Polymer Blends, Composites, IPNS and Gels
Y2 - 21 March 2005 through 23 March 2005
ER -