Fundamental Properties of Asphalts and Modified Asphalts, III

20
these resonances were incorrectly assigned, and now have been tentatively identified as due to
the protons in phosphoric acid. Phosphoric acid is used in preparation of the phosphate esters
and so these resonances would not be unexpected. When D2O was added, these resonances
disappeared due to rapid exchange of the OH proton with the deuterium in heavy water (D2O),
i.e.,
P-O-H + D2O P-O-D + DOH
New resonances appeared at 8.1 and 5.2 ppm. The resonance at 8.1 ppm was not identified; the
one at 5.2 ppm has been tentatively identified as water (HOD).
Innovalt W in H2O
Innovalt W in D2O
15
10
Figure 2-5.5. 1 HNMR spectra of Innovalt W and Kao Gripper in D2O and in H2O.
31 P NMR of Phosphate Ester Antistrips
5
0
-5
-10
20
In a previous quarterly report (Oct.-Dec., 2007) 31 P NMR measurements were made on binder
from four cells taken from the MN Road validation site. Three of the four cells used PPA
(115%) and a phosphate ester antistrip agent, Innovalt W. The 31 P NMR spectra did not show
the presence of the phosphate ester antistrip in the binder.
However, questions have been raised about whether PPA might react with the phosphate ester
antistrip when added to asphalt. Consequently, a NMR investigation has begun to look into this
matter. Initially, 31 P NMR spectra of the neat antistrips, and antistrips with PPA, but in the
absence of asphalt were acquired (figure 2-5.6). The spectra of the neat antistrips show a main
peak at ~0.7 ppm and a minor one at ~0.2 ppm. The minor resonance is better resolved in the
63
KAO Gripper in H2O
KAO Gripper in D2O
Innovalt W neat KAO Gripper neat
Proton Chemical Shift, ppm
15
10
Proton Chemical Shift, ppm
5
0
-5
-10