Scope:

The ASTM D7252-17 test method is suitable for methylene di(the-nyl isocyanate) (MDI) and polymeric (methylene phenyl isocyanate-nate) (PMDI). This test method is used to characterize isocyanates used in polyurethane goods and for research or quality control.

Procedure

In ASTM D7252-17, firstly, to make a mixture of methyl urethanes, the material is treated (derivatized) with methanol. Secondly, normal-phase high-performance liquid chromatography is used to separate the urethanes combination (HPLC). Then, isomers are isolated and derivatized, and lastly, an internal standard is used to quantify the results.

Specimen size

Pump should be of Flow = 1.5 mL/min, Eluent A (hexane) = 90 %,Eluent B (1:1 by volume ethanol:methanol) = 10 %. Detector should have Wavelength = 235 nm, Output Range = 2.000, Injection volume = 2 μL and Column Temperature = 30°C

Data

The percent monomer is calculated in the sample by Monomer, % = Sum of all isomers, %. 

Result

The weight percentage of each isomer and Monomer is calculated and reported to the nearest 0.1 percent.