1070-4272/01/7407-1211$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 7, 2001, pp. 1211!1214. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 7,
2001, pp. 1178!1181.
Original Russian Text Copyright + 2001 by Mikhailov, Lebedeva, Nud’ga, Petrova, Baklagina.
AND POLYMERIC MATERIALS
Composite Fibers Based on Chitin
G. M. Mikhailov, M. F. Lebedeva, L. A. Nud’ga, V. A. Petrova, and Yu. G. Baklagina
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received January 30, 2001
Abstract-Composite fibers containing chitin and cellulose ethers (methyl, hydroxyethyl, and hydroxypropyl
cellulose) and also chitin and polyvinylpyrrolidone were prepared. The effect of the ratio of system com-
ponents and also the molecular weight of polyvinylpyrrolidone on the deformation-strength characteristics
of the composite fibers and their supramolecular organization was studied.
Chitin is nitrogen-containing derivative of cellulose
in which one hydroxy group of the pyranose ring is
substituted by the acetamide group. Similar to cellu-
lose, chitin is capable of forming fibers. However,
high friability of chitin fibers restricts their use; there-
fore, chitin fibers are not produced commercially
throughout the world. Chitin is well crystallized, and
brittle failure of chitin fibers is caused by precisely
this feature . Partial heterogeneous deacetylation
of chitin results in an increase in its structural non-
uniformity and complicates crystallization of macro-
molecules in production of fibers, which increases
their elasticity . At the degree of deacetylation of
chitin equal to or lower than 0.30 the fiber is tied and
retains up to 40% of the initial strength. However,
the use of additional heterogeneous base deacetylation
in the production of chitin fiber, decreasing its fiber-
forming ability, is not appropriate.
It is well known that the structural nonuniformity
of the systems used for production of polysaccharide
fibers hampers crystallization of macromolecules.
This results in an increase in the elasticity of the
fibers. The structural nonuniformity of oriented chitin
can be reached by both its chemical modification and
incorporation of modifying additives into the fiber.
The method of improvement of physicomechanical
characteristics of fibers by their production from a
polymer blend has attracted considerable attention
[3, 4]. For example, on addition of only 0.131.0% of
copolymer of acrylonitrile with methyl acrylate
(95 : 5) to polyamidobenzimidazole the strength of the
fiber increases by 5313% .
Polymers can be blended by mixing their melts or
solutions. Since the temperature of degradation of
polysaccharides (1803200oC) is lower than their melt-
ing point (4503500oC), blends of polysaccharides
with various polymers can be obtained only by mixing
their solutions. In choosing polymer additives to
chitin solutions it is important that these additives
should be compatible with chitin in the solution.
These additives can be cellulose ethers: methyl, hy-
droxyethyl, and hydroxypropyl cellulose, having the
similar structure and different side substituents, and
also polyvinylpyrrolidone (PVP).
Polyvinylpyrrolidone is a unique polymer widely
used in industry and medicine. The main features of
this polymer are ability to complex formation and
solubility in water and organic solvents. It is well
known that grafting of PVP to cellulose fibers im-
proves their elasticity, increases hygroscopicity and
dyeing ability, decreases shrinkage, and increases
laundering resistance of clothes. Addition of PVP as
a modifier to fibers produced from polymers able
to form hydrogen bonds also improves their deforma-
tion-strength characteristics. For example, in modi-
fication of poly-p-phenylene terephthalamide fibers by
addition of PVP to the spinning solution the fiber
elongation at break, strength, aging resistance, fire
resistance, etc. significantly increase . In addition,
prolonged boiling of the fibers modified with PVP
does not result in its removal; the characteristics of
fibers remain the same.
Methyl cellulose, converted to gel at 80oC, and hy-
droxypropyl cellulose, coagulating at 60oC, must re-
main in fibers and hamper crystallization of chitin
in fiber formation.
Therefore, it seemed appropriate to modify chitin
fibers by both above cellulose ethers and PVP and
also to establish the effect of modifying additives
on the structure and characteristics of the composite