Effect of the degree of substitution on the rheology of sodium carboxymethylcellulose solutions in propylene glycol/water mixtures

Abstract

The linear dynamic viscoelastic properties and non-linear transient rheology of sodium carboxymethylcellulose solutions (Na-CMC) in propylene glycol/water mixtures were investigated. Measurements were carried out for the solutions of Na-CMC with three different degrees of substitution (DS), namely 0.62, 0.79, 1.04, and the similar average molecular weight (M w & 250,000 g/mol). The strong synergism between the molecules of Na-CMC with DS of 0.62 and 0.79, and propylene glycol has been observed. The occurrence of the overshoot shear stress and the low loss tangent values indicate the physical cross-linking of the polymer chains. The increase of propylene glycol concentration over 80 wt% and sodium carboxymethylcellulose (DS = 0.7) over 1.6 wt% leads to the formation of a physical cross-link network. The absence of overshoot shear stress and terminal behaviour in SAOS flow of the Na-CMC 1.04 solutions in the PG/water mixture shows that no intermolecular cross-linking of polymer chains occurred in them.

Capillary breakup extensional rheometry of sodium carboxymethylcellulose solutions in water and propylene glycol/water mixtures

“…SAOS measurement results for sodium carboxymethylcellulose solutions in PG/water mixture with a PG concentration of c PG ≥ 70% were discussed by Komorowska et al . The authors showed that the Na‐CMC 0.62 and Na‐CMC 0.79 chains undergo physical crosslinking, probably as a result of the formation of hydrogen bonds between OH groups of propylene glycol and Na‐CMC.…”

“…For Na‐CMC 0.62 and Na‐CMC 0.79 solutions, zero shear viscosity measurements were carried out in the polymer concentration range from 0.01% to 1.4%. Above the concentration of 1.4%, there was a strong increase in viscosity, and zero shear viscosity determination was impossible …”

“…Three sodium carboxymethylcellulose (Na‐CMC) with different degrees of substitution (DS = 0.7, 0.9 and 1.2—based on manufacturer's data) and with a similar weight average molecular weight ( M w = 250,000 g/mol—based on manufacturer's data) were obtained from Sigma‐Aldrich (Poland). The same Na‐CMC samples were investigated in the works Komorowska et al . and Różańska and Różański (taken from the same bottle).…”

“…The procedure for the preparation of the solutions is described in the work of Komorowska et al . . Depending on the concentration of Na‐CMC and propylene glycol, the solution preparation was done in two different ways.…”

“…This article presents the results of CaBER experiments for aqueous solutions of Na‐CMC and Na‐CMC solutions in propylene glycol (PG)/water mixtures. Komorowska et al . observed a strong synergism between molecules of Na‐CMC with a DS of 0.62 and 0.79, and PG.…”