Kinetics of the carboxymethylation of cellulose in the isopropyl alcohol system

Abstract

The carboxymethylation of original and activated cellulose in the system cellulose/NaOH/isopropyl alcohol/ CH,ClCOOH has been investigated by means of conductometry, viscosimetry and X-ray diffractometry. It has been found that the carboxymethylation process in this system is a pseudo-first-order reaction with two stages having different first-ordcr rate constants. By application of the activation method the rate of etherification and the utilization ratio of the etherifying agent were increased and the quality of the product was improved. Kinetik der Carboxymethylierung yon Cellulose i n IsopropylalkoholDie Carboxymethylierung von unbehandelter und aktivierter Cellulose in dem System Cellulose/NaOH/Isopropylalkohol/CH,ClCOOH wurde mittels Konduktometrie, Viskosimetrie und Rontgenbeugung untersucht. Es wurde festgestellt, daB der Carboxymethylierungsprozefi in diesem System eine Reaktion von pseudo-erster Ordnung ist und in zwei Stufen mit unterschiedlichen Geschwindigkeitskonstanten ablauft. Nach einer speziellen Aktivierung der Proben nehmen die Geschwindigkeit der Veretherung und die Ausnutzung des Veretherungsmittels zu, und die Qualitat des Produktes wird verbessert. Runemuxu x a p 6 o x c~e m u~t u p o e a n u~ye~tnm~toaba e wonponanoAe posaHm qenn~onosbr (c aKTmaqnet M 6e3 H t) B cmce ve qennlono3a/NaOH/asonpona~o~1/CH,CICOOH. YcTanocne cneqnanbHoZt aKTHBarlHW o6pasqoB CKOpOCTb aTepm@mKaqAm w pacxoR s~epa@~qrnpy~orqero arema ysenn-MeToHaMm KOHQ' KT3MeTpHH, BHCKOBMMeTPHH II HII@PaKqIIki PeHTreHOBCKWX JIyYet MayqeH IIpOqeCC Kap6OKCWMe THJIII-HOBJIeHO, 9 T O IIpOqeCC IIpOTeKaeT B ABYX CT?HMHX C pa3JIIIsHOfi CKOPOCTbH) IIO peaHqWH IICeBHOnepBOI' O IIOpHnKa. YWBaIoTCH, a TaKXe YJIyYIIIaeTCH KaYeCTBO FOTOBOrO IIpOgyKTa.

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

“…This shows that differences in the scaling exponents for the Na-CMC solutions with varying DS will be related to interactions between the polymer macromolecules (Lewis et al 2014;Shabbir et al 2015). Xiquan et al (1990) demonstrated in X-ray diffraction experiments that in the sodium carboxymethylcellulose aqueous solution for DS B0.82 the derivative crystalline regions are present, i.e. the polymer chains are aggregated by hydrogen bonds.…”

“…The absence of cross-linking of Na-CMC 1.04 macromolecules in the aqueous solutions is most likely an effect of their solvation (Xiquan et al 1990). Probably, also in the PG/water mixture the similar effect might occur.…”

Influence of Organic Diluents on Cellulose Carboxymethylation

“…As in the cases reported earlier, for isopropyl alcohol [5] and acetone and ethanol-acetone systems, [6,7] the kinetics of carboxymethylation in ethanolisopropyl alcohol at molar ratios NaOH/AGU of 2.11 and 3.4 is well described by the pseudo-first-order Equation (1):…”

“…[1 -4] A kinetic study of carboxymethylation of cotton linters and activated cotton linters in isopropyl alcohol has also been reported. [5] The rate constants of the pseudo-first-order reaction have been a good measure of the reactivity of the two types of cellulose. In previous articles [6,7] we discussed the kinetics of cellulose carboxymethylation in three organic media, namely ethanol, acetone, and ethanol-acetone mixtures, in connection with cellulose crystallinity and the concentration of sodium hydroxide in the alkalization step.…”

Optimization of Carboxymethylation of Starch in Organic Solvents

“…Organic solvents are usually used for the preparation of CMC with higher DS [7]. In recent years, several studies have been performed on the effect of organic diluents on carboxymethylation process [8][9][10][11][12].…”