1070-4272/03/7609-1509$25.00C2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 9, 2003, pp. 1509!1513. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 9,
2003, pp. 1548!1552.
Original Russian Text Copyright + 2003 by Medvedeva, Volkova, Semchikov, Tikhomirov.
AND POLYMERIC MATERIALS
Comparative Study of Solutions and Gels of Sodium
Carboxymethyl Cellulose Produced from Cotton
and Wood Cellulose
V. V. Medvedeva, N. V. Volkova, Yu. D. Semchikov, and A. V. Tikhomirov
Research Institute of Chemistry, Lobachevsky Nizhni Novgorod State University, Nizhni Novgorod, Russia
Oktyabr’ Plant, Joint-Stock Company, Nizhni Novgorod, Russia
Received April 24, 2003
Abstract-Viscosity and gelation characteristics of aqueous solutions of sodium carboxymethyl cellulose
produced from cotton and wood cellulose were studied.
Sodium salt of carboxymethyl cellulose (Na-CMC)
is a cellulose ether (CE) produced on a large scale.
This is due to its valuable characteristics and relative-
ly easy production. It finds wide applications in petrol-
eum, textile, food, and pharmaceutical industries as
stabilizing agent, thickener, adhesive, and film-form-
ing substance . Dilute aqueous solutions of
Na-CMC are efficiently structured by multivalent
metal ions with formation of coordinatively cross-
linked gels. These gels are widely used in gas-and-oil
industry as viscoelastic systems in secondary treatment
of oil wells and hydraulic fracturing of strata [4, 5].
All these characteristics of Na-CMC are governed by
the degree of polymerization, degree of substitution,
molecular-weight distribution, and uniformity of
distribution of carboxy groups along the chain [3, 6].
In turn, these characteristics depend on the procedure
of Na-CMC production and also on the raw materials
used in production (such data are scarce).
The aim of this work was to study viscosity and
gelation characteristics of aqueous solutions of
Na-CMC produced from cotton cellulose in com-
parison with the characteristics of Na-CMC produced
from wood cellulose (sulfite cooking).
In the study we used three samples of Na-CMC
produced from cotton cellulose (sample nos. 133) and
two samples of Na-CMC of the 85/600 (sample no. 4)
and 85/800 (sample no. 5) types produced from wood
cellulose. The characteristics of the samples are listed
in Table 1.
All the experiments were carried out at 22+2oC.
Viscosity characteristics of aqueous solutions of
Na-CMC were studied on a Hoeppler ball viscometer.
To prepare gel-forming compositions, we used a
solution of the polymer (2.0 wt %) in double-distilled
water and solutions of chrome3potassium alum
O (1.035.0 wt %), serving as a
cross-linking agent. The initial pH 12.3 was adjusted
with 0.2 wt % KOH. The concentration limits of
gelation and the onset of syneresis were determined
visually [7, 8]. The minimal concentrations of the
polymer and cross-linking agent were determined
from the loss of the solution fluidity under gravity in
turning-over of the ampule in which the cross-linking
occurred after combining the solutions of the polymer
and chromium salt. The onset of syneresis was deter-
mined from the appearance of water drops at the
gel3air boundary. The amount of water separated from
the gel in syneresis was evaluated by weighing. The
modulus of elasticity G of coordinatively cross-linked
Na-CMC gels was determined by penetration using
spherical indentors with various radii depending on
the gel elasticity [9, 10]. The experiment was carried
out at the values of imposed force initiating no creep
of the system. According to the Herz theory , with
the use of a spherical indentor the elasticity modulus
of a gel is given by the relation
G = ÄÄÄÄÄÄÄÄ,
where F is the force applied to the spherical indentor,
R is its radius, and h is the depth of immersion into