ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 12, pp. 2007!2012. + Pleiades Publishing, Inc., 2006.
Original Russian Text + A.M. Bochek, I.L. Shevchuk, L.M. Kalyuzhnaya, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 12,
AND POLYMERIC MATERIALS
Properties of Aqueous Solutions of Methyl Cellulose!Polyvinyl
A. M. Bochek, I. L. Shevchuk, and L. M. Kalyuzhnaya
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received June 9, 2006
Abstract-Rheological properties of dilute and moderately concentrated aqueous solutions of methyl cel-
lulose3polyvinyl alcohol blends, as well as the conditions of gelation in these solutions were studied.
The compatibility of the polymers was examined by the solvent vapor sorption method; the range of the com-
positions corresponding to thermodynamic compatibility of methyl cellulose and polyvinyl alcohol was
Recently there has been increased interest in self-
associated polymer systems based on environmentally
safe and biodegradable natural polymers. As is known,
a number of cellulose compounds form physically
thermoreversible gels in aqueous solutions. These
compounds include methyl cellulose (MC), hydroxy-
propyl cellulose (HPC), hydroxypropyl methyl cel-
lulose (HPMC), and methyl ethyl cellulose (MEC).
These cellulose ethers are widely used as gel-forming
agents, thickeners, stabilizers, and emulsifiers in food
industry . Among the cellulose compounds men-
tioned, the most widely used is MC.
The gelation temperature of aqueous solutions of
MC is affected by many factors: polymer concentra-
tion and degree of substitution and uniformity of dis-
tribution of the substituents in anhydroglucoside units
and along the macrochain . Substituents of a dif-
ferent nature, introduced into the MC macromolec-
ule, affect the solubility of mixed cellulose ethers,
the rheological properties of solutions, their asso-
ciative structural organization, and the gelation and
phase segregation conditions in these solutions .
The rheological properties of MC solutions and con-
ditions of gelation in them, as well as the physico-
mechanical properties of the film obtained from so-
lutions, can be also varied by introducing another
water-soluble polymer into solutions .
Aqueous solutions of MC (systems with lower
critical solution temperature, LCST) form physically
thermoreversible gels under heating , whereas
solutions of polyvinyl alcohol (PVA) (systems with
upper critical solution temperature, UCST) form gels
under cooling . Examination of blends of these
two kinds of polymers in a common solvent is of both
scientific and practical interest.
In this study, we examined the rheological proper-
ties of dilute and moderately concentrated solutions
of MC3PVA blends and the conditions of gelation in
them, as well as the thermodynamic compatibility of
the polymers in the solid state, depending on the poly-
mer blend composition.
As initial materials served MC-100 commercial
cellulose with the degree of substitution of 1.62, M
147 000, and two PVA samples, PVAI with M
17 500 and degree of hydrolysis of 98% and PVAII
= 58 000 and degree of hydrolysis of 98%.
Distilled water served as the solvent.
The 3% aqueous MC and PVA solutions, prepared
in advance, were mixed in the necessary proportions.
Dilution of the 3% solutions yielded 0.153 0.20% so-
lutions, which were examined viscometrically.
An aqueous solution of MC was prepared by poly-
mer swelling in hot water at 80390oC, followed by
dissolution under cooling to 5310oC with stirring for
6 h. The PVA solutions were prepared at 80oC, stirred
for 3 h, and then cooled to room temperature. The re-
sulting solutions were filtered under pressure and then
deaerated for 1 h. The solutions of the two polymers
were mixed in the necessary proportions and stirred
for 4 h.