Hygroscopic study of hydroxypropylcellulose.

Abstract.: The hygroscopic method developed previously for studies of lyotropic liquid crystals is used for the first time in experiments with millimetric capillary bridges made of a hydroxypropylcellulose/water mixture. Composition of such very small samples is controlled via humidity of the surrounding air. By a slow and well-controlled drying of initially isotropic samples, the isotropic/anisotropic phase transition is crossed and polydomain pseudo-isotropic capillary bridges are prepared. Kept in an atmosphere of constant humidity, these bridges are stretched and the strain-induced birefringence $ \Delta$ n is measured as a function of the draw ratio $ \lambda$ . The variation of $ \Delta$ n with $ \lambda$ is interpreted in terms of an affine uniaxial deformation of the initial pseudo-isotropic texture. Graphical abstract: [ABSTRACT FROM AUTHOR]