Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 1, pp. 84−87.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © N.E. Kochkina, V.A. Padokhin, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 1, pp. 84−87.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Mechanical Activation of a Gelatinized Dispersion
of Carboxymethylated Starch
in a Conical Rotor Apparatus
N. E. Kochkina and V. A. Padokhin
Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia
Received April 1, 2010
Abstract—Effect of the shear deformation rate in a conical rotor apparatus on the structure of gelatinized dispersions
of carboxymethylated starch was studied.
Carboxymethylated starches (CMSs) ﬁ nd increasingly
wide use in diverse ﬁ elds of industry: oil- and gas-
producing, food, textile and pulp-and-paper. Recently,
the application ﬁ eld has been steadily increasing [1, 2].
This is due to the unique physicochemical and functional
properties of CMSs: ﬁ lm-forming, water-retaining,
thickening, and emulsifying.
A study of the inﬂ uence exerted by mechanical
impacts on the structural-mechanical properties of
CMS-based liquid-phase systems is of great scientiﬁ c
and practical importance. First, a mechanical treatment
serves as a ﬁ ne tool for control over, and study of, the
structure and properties of gelatinized CMS dispersions.
Second, CMS dispersions are subjected in technological
processes to various mechanical treatments, with their
structure and properties unpredictably changing. To
tackle with practical problems and preserve the quality
of the ﬁ nal materials and products obtained using
CMSs, it is important to be able to reliably predict these
The goal of our study was to examine fundamental
aspects of the evolution of the structure and structure-
sensitive properties of colloid CMS solutions, initiated
by shear mechanical impacts.
As object of study served CMS manufactured by
Polycell Private company: KMK-T type N brand,
with a 0.15 degree of substitution. Gelatinized CMS
dispersions were produced by heating 2 wt % aqueous
suspensions of CMS to 90°C and keeping at this
temperature for 30 min. The samples were mechanically
treated in a conical rotor apparatus (CRA) of original
design. The rotor rotation speed was varied within the
range 2000–5500 rpm, which corresponded to shear
deformation rates of (3.1–7.9) × 10
. The duration
and temperature of the mechanical treatment were 30 s
and 298 K.
The rheological characteristics of the samples were
measured with a Reotest-2 rotation viscometer with
a system of coaxial cylinders. The shear rate was varied
from 1.5 to 1312 s
. The temperature of viscosity
measurements was varied within the range 30–70°C.
The resulting temperature dependences of viscosity
were used to calculate by the Frenkel–Eyring equation
the activation parameters of viscous ﬂ ow of the starch
pastes under study.
The relative viscosity of 0.05% CMS solutions was
determined as the ratio between the time of their outﬂ ow
from a capillary and the outﬂ ow time of a pure solvent,
1 N KOH solution. The measurements were made
with an Ostwald capillary viscometer of VPZh-2 type
with a capillary diameter of 0.56 mm at 293 K. CMS
solutions were prepared from ﬁ lms produced by casting