On the Composites Based on Epoxy Resin - Progress in Organic and Physical Chemistry: Structures and Mechanisms - page 180

FIGURE 8 Dependence of the water-absorption of composites based on epoxy resin on the
concentration of diatomite in binary fillers with andesite (1) - unmodified and modified by 5%
tetraethoxysilane (2) fillers. Total concentration of binary fillers in composites 50 mass %.
The obtained experimental results may be explained in terms of composite struc-
ture peculiarities. Silane molecules displaced on the surface of diatomite and andesite
particles lead to activation of them and participate in chemical reactions between ac-
tive groups of TEOS (hydroxyl) and homopolymer (epoxy group). Silane molecules
create the “buffer” zones between ¿ ller and the homopolymer. This phenomenon may
be one of the reasons of increasing of strengthening of composites in comparison with
composites containing unmodi¿ ed ¿ llers. The composites with modi¿ ed diatomite
display more high compatibility of the components than in case of same composites
with unmodi¿ ed ¿ ller. The modi¿ ed ¿ ller has more strong contact with polymer ma-
trix (thanks to silane modi¿ er) than the unmodi¿ ed diatomite. Therefore, mechanical
stresses formed in composites by stretching or compressing forces absorb effectively
by relatively soft silane phases that is the development of micro defects in carbon
chain polymer matrix of composite districts and ¿ nishes in silane part of material the
rigidity of which decreases.
The structural peculiarities of composites display also in thermomechanical prop-
erties of the materials. It is clear that softening of composites with modi¿ ed by TEOS
composites begins at relatively high temperatures. This phenomenon is in good cor-
relation with corresponding composite mechanical strength. Of course, the modi¿ ed