Chemistry Reference
In-Depth Information
Figure 8.7 FT-IR spectra of (a) castor oil, (b) COPER, and (c) COPERMA.
chains connecting to the hydroxyl groups.
8
The peak at around 4.1 ppm
corresponded to the methylene protons of the polyol backbones connecting
to the ester structure (-CH
2
-O-(C
¼
O)-CH
2
-). The peak at around 0.9 ppm
shows that the terminal methyl protons of fatty acids could also be taken as a
reference. The integral of this peak should show nine protons per castor oil
triglyceride. In the spectrum of COPERMA [Figure 8.8(b)], the typical peaks
at 6.3, 6.9, and 7.1 ppm correspond to the maleate, fumarate, and MA vinyl
protons, respectively. These peaks can be used to determine the reaction
extent of MA.
17
Using the intensity of the peak at 0.9 ppm as a reference, the
maleate, fumarate, and MA vinyl protons were calculated readily. The cor-
responding proton amounts per castor oil triglyceride were 14.81, 0.87, and
1.16, which corresponds to the maleate C
¼
C bonds of 7.41, 0.44, and 0.58,
respectively. Hence, the real maleate C
¼
C functionality of COPERMA was
(7.41
þ
0.44)/3
¼
2.62, which is very high compared to other reported oil-
based macromonomers.
8,11,12,15,17,22
For example, the maleate C
¼
C func-
tionalities were 1.7, 1.3, 1.59, 0.83, and 1.61 for maleate half-esters of
hydroxymethylated soybean oil and sunflower oil, soybean oil pentaery-
thritol glyceride maleates (feed ratio 1 : 2 : 8), COMA (feed ratio 1 : 3), and
tung oil pentaerythritol glyceride maleates (feed ratio 1 : 2 : 8), respectively.
As the maleinization reaction of COPER proceeded, the proton bands at
3.4-3.8 ppm were converted to the bands at 4.1-4.5 ppm, the methylene
protons of the polyol backbones connecting to the ester structure. In add-
ition, a new peak at around 5.05 ppm appeared showing the change of
connecting method of the characteristic methine on the castor oil fatty acid
chain. The peak at around 10.5 ppm is the acid proton provided by the ring
opening of the MA structure during the maleinization.
