Rheological properties of hydrophobically modified carboxymethylcelluloses

This paper describes the rheological properties of two hydrophobically modified carboxymethylcellulose (HMCMC) which differ in their hydrophilic-lipophilic balance (HLB). They were CMC-9C(12-18) (monografted) and CMC-30C(4)-3C(12-18) (bigrafted), where in cote designation CMC-xC(n), x is the percentage of alkyl grafted chain and n the number of carbon atoms in the chain. It is shown that both samples evidence similar behavior although they differ in their HLB. Flow curves show extreme shear thinning behavior that resemble colloidal dispersion behavior, but oscillatory sweep and creep analysis are consistent with a sticky entanglement behavior. It seems that the structure of the pseudo-gel is largely heterogeneous with the presence of very dense zones made up of hydrophobic moieties together with a mainly entangled and sticky network of associated macromolecules. (c) 2004 Elsevier Ltd. All rights reserved.