Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 1, pp. 139−144.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
N.A. Kornilova, I.M. Lipatova, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 1, pp. 142−147.
AND POLYMERIC MATERIALS
Effect of Hydroacoustic Treatment on Structural Organization
of Chitosan Solutions
N. A. Kornilova and I. M. Lipatova
Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia
Received April 28, 2009
Abstract—The effect of hydroacoustic treatment in a rotary-pulsatory apparatus on the rheological, sorption,
and film-forming properties of acetic acid solutions of chitosans was studied.
Chitin, an important representative of natural
polysaccharides of animal origin, and its most known
derivative, chitosan, attract growing practical interest.
Owing to technological convenience determined by
the solubility of chitosan in weakly acidic aqueous
solutions, it is feasible to prepare from this polymer ﬁ lms,
microcapsules, dressings, and membranes, and also carrier
matrices for drugs. Many structure-dependent properties
of these materials and articles are predetermined by
the procedure of preparing the initial solutions from
One of the most efﬁ cient procedures for purposefully
modifying properties of polymer solutions is hydroacoustic
treatment performed in high-speed rotary-pulsatory
apparatus (RPA) . Hydroacoustic treatment is
a complex combination of acoustic (including ultrasonic)
treatments of wide frequency range, with high shear
stresses to which a liquid is subjected in narrow gaps
between elements of the RPA rotor and stator. Previous
studies performed with other polysaccharides showed that
hydroacoustic treatment allows considerable improvement
of process characteristics of solutions and hydrogels of
natural polymers, mainly due to homogenization and
decrease in the extent of their structuring [2–4]. It is
also known that, when polymer solutions are subjected
to intense mechanical actions, the desired dispersion
and disaggregation can be accompanied under certain
conditions by side restructuring processes caused by
high shear stresses [2, 3]. When using RPA for preparing
solutions of natural polysaccharides with improved
process characteristics, it is necessary to make a sci-
entiﬁ cally substantiated choice of the optimal treatment
parameters, taking into account speciﬁ c properties of the
medium being treated.
In this study we examined the effect exerted by
hydroacoustic treatment in RPA on the rheological,
sorption, and film-forming properties of acetic acid
solutions of chitosans.
Experiments were performed with chitosan samples
with MW 5.5 × 10
(CS-550), 4.1 × 10
(CS-410), 1.2 ×
(CS-120), and 0.87 × 10
(CS-87), produced by
Bioprogress (Shchelkovo, Russia). Chitosan samples
were dissolved in 2% aqueous solutions of acetic acid
with stirring for 20 h.
Chitosan solutions were treated in a laboratory RPA
in the recycle mode. The temperature-controlled working
chamber of the apparatus is formed by a rotor and a stator.
Their cylindrical rings have rectangular channels. The
mean gap between the rotating and stationary parts of the
working chamber is 0.5 mm. The rotor rotation rate n was
4000 and 5000 rpm with shear rate gradients of 13.9 ×
and 17.4 × 10
, respectively. The treatment time
was varied within 4–20 s.
The dynamic viscosity of chitosan solutions was
determined with a Rheotest 2 rotary viscometer with the
cylinder-in-cylinder working unit at 25 ± 0.5°С in the
shear rate range 0.2–1.3 × 10