Fundamental Properties of Asphalts and Modified Asphalts, III

100
1% Innovalt W in AAM-1
1% PPA(115%) and
1% Innovalt W in AAM-1
1% PPA(115%) in AAM-1
75
50
25
Figure 2-5.7. 31 P NMR spectra of Innovalt W and KAO Gripper antistrip agents in
PPA modified asphalt AAM-1.
31P NMR Moisture determination
0
Some exploratory work was performed to determine if 31 P NMR could be used to determine the
residual moisture content of asphalt. In part, this work was initiated because previous work had
shown that PPA reacts with residual water in asphalt to form orthophosphoric acid. However,
the extent of hydrolysis cannot be predicted apriori because the amount of residual water in
asphalts is generally not known. A simple method for determining moisture may be useful in
providing more quantitative data about the reaction.
The 31 P NMR method is based on the use of phosphorous compounds that react with water to
form anhydrides. For the moisture determinations, diphenylphosphinic chloride (Ph2POCl), here
referred to as DPPC, was used as the derivatizing agent [Dadey et al. 1988; Wroblewski et al.
1991a,b]. DPPC reacts with water in the presence of base (pyridine) to form the anhydride,
Ph2P(O)OP(O)Ph2 ( 1,1,3,3-tetraphenyldiphosphoxane 1,3-dioxide) according to Scheme I,
2Ph2POCl + H2O + Ph2P(O)OP(O)Ph2 + 2
N
-25
-50
Scheme I
-75
-100
65
100
KAO Gripper in AAM-1
1% PPA(115%) and
1% KAO Gripper in AAM-1
1% PPA(115%) in AAM-1
Phosphorous Chemical Shift, ppm Phosphorous Chemical Shift, ppm
75
50
25
N +
H Cl -
0
-25
-50
-75
-100