120
5
Ri Si X
Organosilane
X Si CH Y General chemical formula of or
- -
[
]
(
)
3
3
2
g ganosilane
[
]
where
5 R is a resin compatible group
5 X is a hydrolyzable group which in turn interacts with glass
surface aqueous solution of organosilane
R Si X
H O R Si OH
HX
Trihydroxysilanol
- -
+
= - ( ) +
(
)
3
2
3
3
3
The common silane coupling agents are trimethoxy(vinyl)
silane, trimethoxy(chloropropyl)silane, trimethoxypropyl glysidoxy silane, trimethoxypropyl(methacrylate)silane, triethoxypropyl- amino-silane, etc. Glass fibre has entrapped oxygen in the
form of an –OH group. This –OH group makes a hydrogen bond
with an –OH group of hydrolysed silane. This hydrogen bond is in
dynamic equilibrium and shifts when experiencing shear force, as
shown in . Fig.  5.2. The labile nature of the hydrogen bond is
Glass
Organo silane
Hydrogen bond
O
O
H
O
Si
O
R
O
R
O
R
O
R
Si
Si
Si
O
O
O
H
O
H
O
H
O
H
H
O
H
O
H
. Fig. 5.2 Hydrogen bonding between glass fibre and organosilane
Chapter 5 · Processability of Thermosetting Composites