Cellulose–poly(acrylamide–acrylic acid) interpenetrating polymer network membranes for the pervaporation of water–ethanol mixtures. II. Effect of ionic group contents and cellulose matrix modification

Abstract

ABSTRACT:The separation properties in the dehydration of a water-ethanol mixture and the swelling behavior of interpenetrating polymer network (IPN) pervaporation membranes based on a cellulose or cellulose-hydroxyethyl cellulose (HEC) matrix and poly(acrylamide and/or acrylic acid) were investigated depending on the ionic acrylate groups content (␥) in synthetic polymer chains (0 -100 mol %), the HEC content in the matrix (0 -50 wt %), and the temperature (25-60°C). The separation factor (␣), permeation rate (P), and separation index (␣P) significantly improved with increasing ␥ values only for the separation of concentrated ethanol solutions (ϳ86 wt %). For more dilute solutions of ethanol (ϳ46 wt %), the P and ␣P values also increased but no considerable increase in ␣ was observed. All types of membranes based on the cellulose matrix were characterized by a drastic decrease in the values of P at [EtOH] Ն90 wt % and, as a result, a decrease in the separation index (kg m Ϫ2 h Ϫ1 ) from ϳ2000 (for 86 wt % EtOH, 50°C) to ϳ240 (for 95 wt % EtOH, 50°C), which correlates with a decrease in the degree of membrane swelling. The modification of the cellulose matrix by introducing HEC into it makes it possible to increase considerably the membrane swelling in concentrated EtOH solutions and, hence, the ␣P value to ϳ760 (95 wt % EtOH, 50°C). All types of IPN membranes exhibit a marked increase in both ␣ and P when the temperature increases from 25 to 60°C.

Anisotropic swelling and mechanical behavior of composite bacterial cellulose–poly(acrylamide or acrylamide–sodium acrylate) hydrogels

“…Samples of BC-PAAm hydrogels were prepared using the technique of composite hydrogel material synthesis that we have developed previously (Buyanov et al, 1998(Buyanov et al, , 2001. BC plates with two different water contents (∼99 or ∼86 wt%) were used as matrices for hydrogel synthesis.…”

“…By using this method we have developed hydrogel membranes consisting of cellulose-PAAm and cellulose-polyacrylic acid (PAA) compounds. At the expense of the high rigidity of the cellulose carcass, these hydrogels possess high mechanical strength and stiffness, and at the same time demonstrate all valuable properties inherent to PAAm and PAA (Buyanov et al, 1998(Buyanov et al, , 2001.…”

Synthesis and characterization of interpenetrating networks from polycarbonate and cellulose acetate butyrate

“…Natural polymers and their derivatives such as gelatin [3], sodium alginate [4], chitosan [5 -9], chitin [10], cellulose [11] and cellulosic compounds [12 -14] have been used for the preparation of hydrogel type semi-IPN materials. Natural polymer based IPNs have been also investigated for applications in pervaporation techniques in order to improve separation properties or to elaborate more complex structures [15]. Nguyen et al have reported the preparation of high-performance pervaporation asymmetric membranes for the selective removal of ethanol by using semi-IPN materials in which a linear cellulose ester is embedded in a photopolymerized methacrylate network [16,17].…”

Synthesis and characterization of konjac glucomannan/poly(vinyl alcohol) interpenetrating polymer networks

“…4 IPN materials have drawn much attention because of the special properties brought about by the interlocking of polymer chains. 5 Polyurethane, 6 acrylic acid ester, 7 and epoxy resin 8 are the usual materials for IPNs; however, research on IPN materials from cellulose, 9 poly(vinyl alcohol) (PVA), 10,11 etc. also revealed interesting results.…”