ASTM D5155-19 Determination of the Isocyanate Content of Aromatic Isocyanates

Introduction:

The ASTM D5155-19 standard offers a modeled methodology to ascertain the degree of isocyanate content in aromatic isocyanate materials. Isocyanate materials are considered among the essential raw materials used to produce polyurethanes. The methodology standard is significant in ensuring consistency and quality of isocyanate materials, which is critical as isocyanate content may influence the properties and performance of final polyurethane materials. In the statistical approach, the isocyanate sample is transformed when it reacts with an excess dibutyl amine, forming the corresponding urea. The reaction is monitored, measured, and quantified when an attempt is made to assess isocyanates found in the sample material. The formalized testing protocol pares time into an efficient process that engenders reliable, repeatable, and reproducible results, paramount for abiding by strict manufacturing requirement controls for required specifications.

ASTM 5155-19 SI Unit:

The isocyanate results by the ASTM 5155-19 method should follow SI units. SI units also provide the standard measurement of comparison when reporting measurement values from the ASTM 5155 -19 laboratory method as consistency across reporting and the same per application process fulfills quality control and the same effects throughout processed materials.  

Scope of ASTM D5155-19: 

In addition to representing significant value for research and quality control applications, the context of ASTM D5155-19 is diverse and enables the characterization of isocyanates in the formulation of polyurethane products. This is especially relevant to several industries, such as automotive, construction, and consumer goods manufacturing, that depend on polyurethane’s proper formulation and performance in operational applications. ASTM D5155-19 comprises three separate test methods that enable researchers to determine the content of crude or modified isocyanates. The isocyanate must be suitably reactive and soluble for its intended application. The quantitative determination of isocyanate content allows the characterization of raw isocyanate materials to define and document their suitability for high-performance polyurethane products. The ASTM D5155-19 test methods can determine isocyanate content reliably yet, more importantly, can facilitate quality assurance to allow for streamlined production processes, increasing the product’s performance and improving overall environmental compliance and safety in polyurethane-based materials.  

ASTM D5155-19 Test Procedure

In all three test methods provided in ASTM D5155-19, researchers react to the isocyanate sample with an excess dibutyl amine to form the corresponding urea. The amount of dibutyl amine consumed in the reaction determines the NCO content. The test methods differ in the reaction conditions, solvents, or both.

Specimen Size

The size of test samples suitable for applying the Laser-Flash Method usually lies between thin little disks whose diameters are about 6 to 12 millimeters and whose thicknesses are from 1 to 3 millimeters, varying with the tested material and process apparatus. Further, one of the requirements is that the thickness of the samples must be uniform, and the surfaces of the samples must be flat and parallel to have the maximum impact on the results and make the tests reliable. It is also possible that the samples are small or thin for materials with a high thermal diffusivity, while the samples for testing the above-discussed narrow range are more extensive and thicker. Therefore, researchers must maintain the humidity level in the laboratory as one of the critical conditions for the material samples.

Results

The ASTM D5155-19 test result is the average of duplicates, expressed as percent NCO, to the nearest 0.01%.

Conclusion:

ASTM D5155-19 is a crucial test standard for determining the isocyanate contents of aromatic isocyanates used in polyurethane production. The aromatic isocyanate reactivity is also vital. Moreover, the standard ensures quality, consistency, and performance by measuring the product in refined tests. As a result, ASTM D5155-19 plays a vital role in guaranteeing the product’s quality, consistency, and performance.

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