SOLUTION VISCOELASTIC PROPERTIES OF OATRIM-10 AND COOKED OAT BRAN

The solution rheological behaviors of OATRIM-10 and cooked oat bran we re investigated. The rheological properties of the materials were inve stigated using both thixotropic loop and small-amplitude oscillatory s hear experiments. The cooked oat bran exhibited shear-thinning behavio r during a thixotropic loop experiment over a shear rate range of 0-25 0/sec. The shear-thinning behavior was reproduced during the measureme nt of a second thixotropic loop, in contrast, OATRIM-10 exhibited an u nexpected region of shear-thickening behavior at 20-80/sec. The shear- thickening and subsequent sheer-thinning regions for OATRIM-10 could b e described by a transient network model indicating that the shear-thi ckening behavior is caused by a shear-induced entangled network that i s partially disentangled at higher shear rates. Subsequent thixotropic loop experiments displayed the shear-thickening region for OATRIM-10, indicating that the network structure can be reformed during the impo sition of a sheer field. Small-amplitude oscillatory shear data for co oked oat bran can be described reasonably well using a generalized lin ear viscoelastic (GLV) model. The oscillatory shear data obtained for OATRIM-10 could not be described by the GLV model. OATRIM-10 exhibited a distinctive plateau centered at 10/sec, and the low frequency respo nse of storage modulus G' decreased with a much larger slope in freque ncy than was predicted by the GLV model.