Comparative Rheological Behavior of Some Cellulosic Ether Derivatives

Abstract

The shear flow of cellulosic derivatives (methylcellulose and hydroxypropylmethylcellulose with different degrees of methoxyl and hydroxypropyl substituents) has been studied. The static light scattering and intrinsic viscosity measurements have allowed the determination of the weight-average molecular weight (M w), radius of gyration (R g), critical overlap concentration C*, intrinsic viscosity [η], and Huggins constant. These results indicate that the studied methylcellulose A4M and hydroxypropylmethylcellulose F4M have comparable molecular weight and an intrinsic viscosity of the same magnitude in pure water. However, hydroxypropylmethylcellulose K4M possesses a greater molecular weight and a corresponding high value of [η]. Even if hydroxypropylmethylcellulose F4M and K4M have different molecular weights and different [η], they show a rather similar C* value. Although the critical parameter is the same for A4M and F4M, the C r* concentration characterizing the end of the dilute regime is lower in the case of methylcellulose derivative, indicating that the absence of any hydroxypropyl substituent on the polymer chain is responsible for the A4M chains to develop associative interactions among themselves more favorably. This may be explained by their tendency to escape from the aqueous medium. Although the studied hydroxypropylmethylcellulose samples differ from their methoxyl degree of substitution and their hydroxypropyl molar substitution (F4M, DS = 1.76, MS = 0.14; K4M, DS = 1.39, MS = 0.21), their aqueous solutions display a rather similar rheological behavior in steady flow, suggesting that the distribution of the various substituents along the polymer chain does not induce a great difference on the interactions that lead to entangled structures of comparable density and cohesion.

Carboxymethyl cellulose film from durian rind

“…It is well known that the viscosity of CMC is influenced by many factors including CMC concentration (El Ghzaour, Trompette, Cassanas, Bardet, & Fabregue, 2001), sodium monochloroacetate (NaMCA) concentration (Adinugraha et al, 2005), NaOH concentration (Heinze & Pfeiffer, 1999) and temperature (Rachatanapun & Rattanapanone, 2011). The viscosity of the CMC d solution (1 g/ 100 mL) decreased when the experiment temperature was increased (Fig.…”

Synthesis and Characterization of Carboxymethyl Cellulose from Sugarcane Bagasse

“…The Same trend was observed for DS of CMC b meaning that higher DS values provided the polymer with greater hydrophilic groups which facilitate water molecules to easily pass through the films by dissolution-diffusion mechanism. It is obvious from different literatures that water vapor transmission rate through hydrophilic films depends on diffusivity and solubility of water molecules in the films Matrix [38,39]. In general, polymer polarities increased by conversion of cellulose to carboxymethyl cellulose also causes crystallinity reduction and changes in the granular morphology [40].…”

Thermo sensitive behavior of cellulose derivatives in dilute aqueous solutions: From macroscopic to mesoscopic scale

“…Such polymers or copolymers are usually made of hydrophilic and hydrophobic moieties (blocks or pendent groups) which are able to self associate in aqueous media via intra and/or intermolecular interactions according mainly to the amount and nature of hydrophobic groups and the polymer concentration domain [3][4][5]. These peculiar systems are used as enhancer thickeners [6], in the control of interface [7,8] or more recently in drug delivery applications [9,10].…”

“…Specific thermal transition of such systems (clear to cloudy, coil to collapse, liquid to gel) have been characterized using different experimental techniques like turbidimetry [20], tensiometry [21], viscometry [22], rheology [3,23], fluorescence [24,25] and differential scanning calorimetry (DSC) [26,27]. Efficiency of these thermoassociative polymers usually depends on their interfacial and bulk associations [27,28].…”