Integrated neutron Couette system for nonequilibrium studies of polymers under flow

A temperature-controlled Couette-type shear system has been designed and constructed allowing in situ the simultaneous neutron scattering and the optical microscopy study of the nonequilibrium states of thermotropic complex fluids subjected to a steady-state shear flow. In contrast to the usual neutron Couette devices, this cell is adapted to the rheology of viscous materials (typically, 500-1000 Pa s), which can be examined in a wide temperature range (from room temperature to 140 degreesC). An optical magnification lens is coupled to the shear system to allow the observation of the texture evolution of mesophases. A recent experiment carried out at the vicinity of the nematic-isotropic transition of a side-chain liquid-crystalline polymer is presented. (C) 2001 American Institute of Physics.