Other Isocyanate Analytical Terms

As the chemical reaction occurs on a 1 1 equivalent weight basis, 1162 g of this polyol would react with 125g of MDI, or 110-5 g of the polymeric  

MDI discussed earlier. This 1 1 equivalent weight ratio is called the isocyanate index. 

Note Normally excess isocyanate is used to compensate for allophanate and biuret readings. 

The isocyanate equivalent is defined as the weight of sample which will combine with 1 g equivalent weight of phenyl isocyanate. The sample is generally a polyol, amine or other compound that possesses groups capable of reacting with an isocyanate. 

Amine equivalent is defined as the weight of sample which will combine with 1 g equivalent weight of dibutylamine. 

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