1070-4272/01/7403-0516$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 3, 2001, pp. 516 !518. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 3,
2001, pp. 505!507.
Original Russian Text Copyright + 2001 by Osovskaya, Poltoratskii.
Effect of Aqueous Solutions of Biuret, Dimethyl Sulfoxide,
and Acetamide on the Paper-Forming Properties of Cellulose
I. I. Osovskaya and G. M. Poltoratskii
St. Petersburg State Technological University of Plant Polymers, St. Petersburg, Russia
Received June 20, 2000
Abstract-Chemical activation of cellulose material was studied as a means to improve the mechanical char-
acteristics of experimental paper.
This report is a continuation of our previous article
 in which we suggested a principally new approach
to choosing a cellulose activator, based on thermody-
namic studies and a few available publications .
We showed in  that the degree of cellulose activa-
tion with an aqueous solution of a chemical reagent
depends on the structure of the solvent (liquid water),
which is, in turn, determined by the nature and con-
centration of the solute. Based on thermodynamic
studies (calorimetry, densimetry), we proved that
water in the presence of structure-breaking and struc-
ture-making electrolytes transforms the hydrophilic
and sorption properties of cellulose by affecting its
structure . It was shown that the most promising
activating agent is biuret which, when added in small
concentrations (335 wt %), facilitates maximal devel-
opment of the capillary-porous structure of cellulose
and makes it more accessible for the liquid medium.
The goal of this study was improvement of the
paper-forming properties of the cellulose material by
optimization of cellulose activation with aqueous
solutions of organic substances. We studied the physi-
comechanical properties of experimental paper that
was obtained from cellulose activated with aqueous
solutions of biuret, dimethyl sulfoxide (DMSO), and
acetamide. Experiments were performed with bleached
sulfate cellulose (Arkhangelsk Pulp-and-Paper Plant,
Joint-Stock Company) which had the following char-
acteristics: a-cellulose content 91.8%, degree of poly-
merization 1700, degree of crystallinity 65%, and ash
residue 6%. Activated cellulose was prepared by stir-
ring a 6% cellulose suspension for 2 min in the pres-
ence of an activator, washed with distilled water, and
squeezed to a cellulose concentration of 50 wt %.
Experimental castings of 100+1gm
prepared on a sheet-casting machine and subjected to
standard physicomechanical tests. The concentration
of the organic component was varied within 035wt%.
The results of physicomechanical tests are given in
Figs. 1 and 2 and in the table.
Figures 1a and 1b show that the effect of cellulose
activation with aqueous solution of an organic sub-
stance depends on its nature and concentration. The
breaking length BL and relative elongation e
substantially increase as the concentrations of biuret
and DMSO are increased to 1.5 and 5 wt %, respec-
Fig. 1. Effect of concentration C of (1) biuret, (2) DMSO,
and (3) acetamide in aqueous solution on the (a) breaking
length BL and (b) relative elongation e
of paper formed by
the traditional procedure.