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