1070-4272/04/7704-0694 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 4, 2004, pp. 694!696. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 4, 2004,
Original Russian Text Copyright + 2004 by Nikulin, Akatova.
Effect of Polycaprolactam Fiber on Coagulation
of Rubbers and on Properties of Rubbers,
Rubber Stocks, and Vulcanizates
S. S. Nikulin and I. N. Akatova
Voronezh State Academy of Forestry Engineering, Voronezh, Russia
Received March 7, 2003
Abstract-The effect of polycaprolactam fiber on the coagulation of butaidene3styrene rubber from the latex
Large amounts of wastes of fibers and fibrous
materials are formed at textile and clothing factories.
Utilization of these wastes is a topical problem .
In industry, fibrous fillers are introduced into poly-
mers on rollers in the course of preparation of rubber
stocks [5, 6]. The fillers impart the required rigidity
and enhance the strength of rubber items. However,
introduction of a fibrous filler on rollers does not en-
sure its uniform distribution in the bulk of the rubber
stock, which negatively affects the physicomechanical
parameters of the vulcanizates.
Hence, it is necessary to ensure, with minimum ex-
penditure, a uniform distribution of a fibrous filler in
the bulk of a polymeric compound. One of the ways
to achieve this goal is introduction of a fibrous filler
into a polymer in the latex step in production of
In this study, we analyzed how the polycaprolac-
tam fiber affects the coagulation of a latex of SKS-30
ARK butadiene3styrene rubber (BSR) and the proper-
ties of rubbers, rubber stocks, and vulcanizates.
First we considered several modes of pretreatment
of a fibrous filler, polycaprolactam, before its mixing
with BSR latex. The size and dosage of the filler were
kept constant: 2 mm and 0.5 wt % relative to the
rubber. The fibrous filler was introduced without
pretreatment (dry) and after wetting with various
agents: water, tallow soap solution, 24 wt % NaCl
solution (coagulant), and 2% H
Introduction of the fibrous filler without pretreat-
ment (in the dry form) or after wetting with water
does not ensure the desired effect. Better results are
obtained after pretreatment of the fiber with a tallow
soap solution. However, this involves additional mate-
rial and economic expenditures. Introduction of the
fibrous filler in combination with the coagulating
agent does not noticeably affect the coagulation.
Treatment of the fiber with sulfuric acid slightly
increases the coagulum yield. This may be due to
the fact that the amide groups of polycaprolactam
macromolecules react with sulfuric acid molecules.
Appearance of quaternary ammonium groups in the
macromolecules should stabilize the coagulation pro-
cess. The possibility of using quaternary ammonium
salts for coagulation of rubbers from latexes has been
shown previously [7, 8].
Therefore, apparently, the best choice will be intro-
duction of the fibrous filler with an acidifying agent
in the final step of coagulation.
Further experiments on the influence exerted on
the coagulation by the dosage and length of a poly-
caprolactam fiber were performed with simultaneous
addition of the fiber and the acidifying agent. The
fiber length was 2, 5, and 10 mm, and the dosage,
0.1, 0.3, 0.5, 0.7, and 1.0 wt % relative to the rubber.
The influence of the fiber length (at a dosage of
0.3 wt % relative to the rubber) and NaCl dosage on
the coagulum weight is illustrated by the figure. Sim-
ilar dependences of the coagulum weight on the NaCl