Chemistry Reference
In-Depth Information
reaction temperature and time, dosage of catalyst, dosage and concentration of alkali
and type of solvents. The synthesis route is shown in
Figure 3.2
and the optimum
reaction conditions were as follows: 1 mol HTMA with 1.5 wt% phase transition
catalyst were added to 10 mol epoxychloropropane (as a solvent) and 1.9 mol solid
sodium hydroxide was added as a hydrogen chloride acceptor, at 70 ℃ for 4 h.
Under these conditions, the yield was 94.1%. The epoxy resin was a transparent,
light yellow liquid with an epoxy value (the mole amount of epoxy group per 1 g
resin) of 3.5-3.9 mmol/g. The viscosity of the epoxy resin was 1.7 Pa-s at 50 ℃. This
type of epoxy resin has better ultraviolet resistance than terpinene-maleic ester type
epoxy resin because the double bond in the molecular backbone was hydrogenated.
They can be used for outdoor insulation materials.
O
O
O
C
O
O
C
Catalyst
C
C
H
C
H
2
H
2
H
H
2
H
2
H
C
+
+
O
Cl
H
2
O
H
2
C
C
O
C
O
C
C
C
O
C
O
C
CH
2
O
n
O
O
OH
O
Figure 3.2
The synthesis route of terpene-maleic ester type epoxy resin
Afterwards, Wu [6, 7] prepared three polyols by reacting HTME with secondary
amines (diethylamine,
N
-methylethanolamine, and diethanolamine). The preparation
of these polyols is shown in
Figure 3.3
. These polyols were used in place of commercial
polyols to prepare two-component polyurethanes. The tertiary amine groups included
in the polyols could catalyse the crosslink reactions of the polyol with polyisocyanate.
The drying times of these polyols are relatively shorter than those of the commercial
polyols. The crosslinked products, which could be called epoxy-urethane polymers,
had excellent impact strength, adhesion, flexibility, water resistance and chemical
resistance as shown in
Table 3.1
. The pencil hardness and alcohol resistance of the
crosslinked products were in accordance with the hydroxyl functionality and hydroxyl
value of each polyol, and the larger hydroxyl functionality and hydroxyl value of the
polyol led to better properties in the crosslinked products. Because the larger hydroxyl
functionality and hydroxyl value resulted in a higher crosslinking density, the rigidity
and alcohol resistance of the crosslinked products were improved. The crosslinked
products of the polyols showed good thermal resistance, and the temperatures at 5%
weight loss (
T
5%
) were all above 230 ℃. The larger functionality and hydroxyl value
of the polyol also resulted in a better thermal stability in the crosslinked product of the
polyol. The product from the HTME-diethanolamine (DEA) polyol had the highest
T
5%
at 276 ℃ because it had the highest crosslink density, and the
T
5%
values of the
products from the HTME-
N
-methylethanolamine (MEA) and HTME-diethylamine
(DeA) polyols were 242 and 235 ℃, respectively.
