Chemistry Reference
In-Depth Information
methylol groups. The disappearance of carboxyl peaks (at 13 ppm) and appearance
of two peaks at 2.82 ppm (CH
2
epoxy), 2.94ppm (-OCH
2
-epoxy) and3.43ppm (-CH-
epoxy) indicated the formation of glycidyl ether and ester group [37].
2.4.3 Characterisation of Glycidyl Ether of Diabiety Ketone
The synthesis of a multifunctional epoxy resin from the tetrahydroxyethyl ether of
DAK was discussed [36]. The epoxy resin produced from reaction of DAKA with
EC designated as DAKAE. The physicochemical properties of the prepared resins
(molecular weight, viscosity, EEW, acid value and hydroxyl number) are listed in
Table 2.5
. Careful inspection of the data listed in
Table 2.6
reveals that the glycidyl
ether of MA/DAKAE have higher EEW, viscosity values than that determined for
AA/DAKAE derivative. It was also of glycidyl ether based on MA-/DAKAE and AA-/
DAKAE have epoxy functionalities equal 3.8 and 3.9, respectively. This indicates
that the terminated hydroxyethyl groups were reacted with EC for both AA/DAKAE
and MA/DAKAE.This was also proved from the higher hydroxyl value of glycidyl
ether based on MA/DAKA than that based on AA/DAKA. This can be attributed
to hydrolysis of epoxy groups which added new hydroxyl groups to unreacted
hydroxyl groups. The hydrolysis of the epoxy group affects the viscosity values and
decreases the viscosity of the glycidyl ether based on MA/DAKA. The structures of
the produced glycidyl ethers of MA/DAKAE and AA/DAKAE were confirmed by
IR and ¹H-NMR spectroscopy. The presence of epoxide groups in the IR spectra of
the glycidyl ethers of both MA/DAKAE (and AA/DAKAE was investigated from the
presence of strong bands at 790 cm-
1
and 850 cm
-1
(γ
C-O
epoxy). This was also proved
from their ¹H-NMR spectra, indicated from the appearance of bands at 3 ppm (C-H
epoxide) and 2.3 ppm (CH
2
-epoxide). The integrations of peaks between hydroxyl
groups (at δ = 2.5 ppm) and the CH- proton of epoxy (at δ = 3 ppm) can be used to
determine the epoxy functionality of the resin. It was noted that the hydroxyl protons
of the glycidyl ether of AA-DAKAE have the same ratio of integration as do the C-H
epoxy protons. The disappearance of the peak at 2.5 ppm (hydroxyl proton) in the
¹H-NMR, spectrum of the glycidyl ether of MA-DAKA indicates that the reaction of
EC with tetrafunctional hydroxyethyl groups of MA-DAKA is complete.
