ASTM D4660 Determination of the Isomer Content of Toluene diisocyanate

Scope:

The ASTM D4660 test method is essential to get accurate readings at different sample concentrations. It helps determine the isomer content of toluene diisocyanates. It defines a standard to control the quality and application of these diisocyanates. It characterizes the isocyanates found in polyurethane products and is applicable for research purposes. It determines the isomer content by considering the infrared spectrum of the sample. It provides information about the reactivity of toluene diisocyanates which helps specify their reliability and their application.  

Procedure:

The apparatus for ASTM D4660 testing consists of a spectrophotometer, NaCl liquid absorption cell, and a 25 mL glassware. The apparatus is set up to determine the isomer content of toluene diisocyanates. A dry pipette is used to add 0.98 g of the sample into a volumetric flask, which is then diluted with anhydrous cyclohexane. The 0.2 mm cell is filled with cyclohexane, and the solvent spectrum is observed. The same is done by filling the cell with the sample solution. This test method provides quantitative measurement of absorption bands formed by the deformation of C-H bonds in the aromatic ring. The infrared spectrum of the solutions is recorded and the absorbance ratio is determined.

Specimen size:

For ASTM D4660, the sample is taken as per the requirements. The 0.98 g sample consisting of either 5 to 95% of toluene-2,6-diisocyanate or 0 to 5% toluene-2,6-diisocyanate is taken.

Data:

The percentage of each isomer can be calculated for ASTM D4660 testing by using the isomer weight ratio, (R), as follows:

Percent 2,6-TDI ꞊ 100/(R+1)
Percent 2,4-TDI ꞊ 100 – percent 2,6-TDI

Conclusion:

The ASTM D4660 test method is essential to get accurate readings at different sample concentrations. It helps determine the isomer content of toluene diisocyanates.