Strain-induced matrix and droplets anisotropic deformation in liquid crystalline cellulose dispersed liquid crystal films

被引:5
作者
Filip, D.
Costa, I.
Figueirinhas, J. L.
Godinho, M. H.
机构
[1] Univ Nova Lisboa, FCT, Dept Mat, P-2829516 Caparica, Portugal
[2] CENIMAT, P-2829516 Caparica, Portugal
[3] Petru Poni Inst Macromol Chem, Iasi 700487, Romania
[4] UL, CFMC, P-1649003 Lisbon, Portugal
[5] IST, Dept Fis, P-1049001 Lisbon, Portugal
关键词
cellulose liquid crystals; dispersed liquid crystals; band texture; liquid crystal ellipsoids; optical microscopy; light scattering;
D O I
10.1163/156855406777408539
中图分类号
TB33 [复合材料];
学科分类号
摘要
The present work deals with the preparation of new liquid crystalline cellulose dispersed liquid crystal films (100 mu m) 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.
引用
收藏
页码:477 / 486
页数:10
相关论文
共 23 条
[1]
Cross-linked hydroxypropylcellulose films: mechanical behaviour and electro-optical properties of PDLC type cells [J].
Almeida, PL ;
Tavares, S ;
Martins, AF ;
Godinho, MH ;
Cidade, MT ;
Figueirinhas, JL .
OPTICAL MATERIALS, 2002, 20 (02) :97-100
[2]
Optomechanical properties of stretched polymer dispersed liquid crystal films for scattering polarizer applications [J].
Amimori, I ;
Priezjev, NV ;
Pelcovits, RA ;
Crawford, GP .
JOURNAL OF APPLIED PHYSICS, 2003, 93 (06) :3248-3252
[3]
OPTICAL-PROPERTIES OF STRETCHED POLYMER-DISPERSED LIQUID-CRYSTAL FILMS [J].
APHONIN, OA ;
PANINA, YV ;
PRAVDIN, AB ;
YAKOVLEV, DA .
LIQUID CRYSTALS, 1993, 15 (03) :395-407
[4]
FIGUEIRINHAS JL, 2005, POLYSACHARIDES STRUC, V2
[5]
Atomic force microscopy study of hydroxypropylcellulose films prepared from liquid crystalline aqueous solutions [J].
Godinho, MH ;
Fonseca, JG ;
Ribeiro, AC ;
Melo, LV ;
Brogueira, P .
MACROMOLECULES, 2002, 35 (15) :5932-5936
[6]
Novel PDLC type display based on cellulose derivatives [J].
Godinho, MH ;
Martins, AF ;
Figueirinhas, JL .
LIQUID CRYSTALS, 1996, 20 (03) :373-376
[7]
Investigation of the band texture occurring in acetoxypropylcellulose thermotropic liquid crystalline polymer using rheo-optical, rheological and light scattering techniques [J].
Harrison, P ;
Navard, P ;
Cidade, MT .
RHEOLOGICA ACTA, 1999, 38 (06) :594-605
[8]
Thermotropic cholesteric liquid crystals in ester derivatives of hydroxypropylcellulose [J].
Kosho, H ;
Hiramatsu, S ;
Nishi, T ;
Tanaka, Y ;
Kawauchi, S ;
Watanabe, J .
HIGH PERFORMANCE POLYMERS, 1999, 11 (01) :41-48
[9]
LIQUID-CRYSTALLINE PHASE-TRANSITION OF A SEMIFLEXIBLE POLYMER - (ACETOXYPROPYL)CELLULOSE [J].
LAIVINS, GV ;
GRAY, DG .
MACROMOLECULES, 1985, 18 (09) :1753-1759
[10]
LIQUID-CRYSTAL ELASTOMERS BASED UPON CELLULOSE DERIVATIVES [J].
MITCHELL, GR ;
GUO, W ;
DAVIS, FJ .
POLYMER, 1992, 33 (01) :68-74