1070-4272/05/7810-1674 C 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 10, 2005, pp. 1674!1677. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 10, 2005,
Original Russian Text Copyright + 2005 by Starokadomskii, Fedorenko.
AND POLYMERIC MATERIALS
Physicomechanical Properties of Photocured Composites
as Influenced by the Degree of Filling with Silica
of Various Particle Sizes
D. L. Starokadomskii and O. M. Fedorenko
Institute of Surface Chemistry, Ukrainian National Academy of Sciences, Kiev, Ukraine
Received July 5, 2004; in final form, August 2005
Abstract-The strength of photocured composites as influenced by the concentration and specific surface
area of a silica filler was studied.
Photocured composites used in various branches
of industry are promising materials owing to their
high quality and relatively simple curing procedures.
Filling is the main procedure for integrated control
over the polymer properties. Filled photocured com-
posites are of particular interest in view of their
expanding use in stomatology and microelectronics
 and prospects for their use in other branches
of industry (e.g., in automobile and aircraft build-
ing). Applicability of filled photocured composites
is primarily determined by their strength. The com-
pression strength, microhardness, and abrasion re-
sistance are the main parameters characterizing photo-
cured composites for stomatology . The strength
parameters also furnish certain information on
the composite structure [9, 10].
In this study, we examined the strength of filled
photocured composites as influenced by the con-
centration and specific surface area of the silica
The following chemicals were used: a,w-bis(meth-
ene (OKM-2), triethylene glycol a,w-dimethacrylate
(TGM-3), and ethoxybisphenol a-dimethacrylate (EPO)
[Dzerzhinsk, Russia] oligomers; Aerosils A-100,
A-175, A-300, and A-455 [Kalush, Ukraine] (addi-
tionally calcined at 400oC for 1 h), silica gels were
modified using K-2 and A-174 silane acrylates [Red’-
kino, Russia]; benzyl dimethyl ketal (BDK) [Ciba
(Switzerland)] photoinitiating agent; and tris(dimeth-
ylaminomethyl)phenol (TMP), N,N,N,N-tetrameth-
ylehexamethylenediamine (THA), and N,N,N,N-tetra-
methylenethylenediamine (TMEDA) activators.
Oligomer OKM-2 containing 0.6 wt % DBK and
0.130.2 wt % TMP, THA, or TMEDA was used as
a polymeric matrix for filled photocurable composites.
This composition was filled with various amounts of
A-175, A-300, A-380, and A-455 Aerosils. As a rule,
we used in our experiments the composition consist-
ing of OKM-2 + 0.6 wt % BDK + 0.1wt % TMP
(hereinafter named as matrix).
The compositions were photocured using a DRUFZ-
125 lamp (17.3 W m
, l 3003400 nm) placed at
distance of 10320 cm from the sample. The physico-
mechanical propertiesof the resulting photopolymers
were measured in conformity with the following
GOSTs (State Standards): compression resistance s
(MPa), GOST 232026378, 4651382; abrasion wear
), GOST 110127369; microhardness
(MPa), GOST 4670371; flexural strength s
(MPa), GOST 25604382; and impact resilience F
(MPa, GOST 9454378).
In filling of oligomers, the limiting concentrations
of silica can be attained, namely, the limiting filler
and concentration of the fluidity loss,
. At silica concentration higher than c
posite loses stability (self-dispersion) and its strength
properties decrease to zero, and at c > c
flow of the composite is terminated. Apparently, c
should show an inverse correlation with the
specific surface area S of silica. Indeed, as can be seen