| Abstract: | Partly as a result of the high solution viscosity of bacterial cellulose, carboxymethylcellulose (CMC) derived from this material exhibits shear-thinning and thixotropic properties. With suitable sample treatment, the CMC solution shows gel-like rheology suggesting the presence of a three-dimensional network. This behavior is consistent with heterogeneous substitution of the carboxymethyl functionality on the polymer chains. For comparison, bacterial cellulose is also degraded by either acid or ultrasound to reduce its molecular weight and converted to CMC. The flow behavior of the resulting CMC solutions is nearly Newtonian with slight shear thinning but no thixotropy, suggesting that the carboxymethylation reaction is almost random. |
