Prepolymerized isocyanate reaction

In this polyurethane-prepolymerized isocyanate reaction, the fastest catalyst are the acetylacetonate complexes. Looking at the molecular structures involved, an octoate is a 2-ethylhexoate, having the structure... 

Belin L, Hjortsberg Ulf, Wass U. 1981. Life threatening pulmonary reaction to car paint containing a prepolymerized isocyanate. Scand J Work Environ Health 7 310-311. 

One-Shot vs. Prepolymerization Reactions. If isocyanate and active hydrogen compounds can be mixed all at once, this one-shot process is simpler and more... 

The first source of processing variety comes into play when the question of when and how this polymerization reaction takes place. Raw materials may be liquid components or they may be solids in the form of powders, granules, or pellets. The raw materials may be presented for processing in a prepolymerized form (polyethylene or acrylonitrile/butadiene/styrene [ABS]), they may be in a partially reacted form (urethanes = polyols + isocyanates), or they may be in the state of their precursor raw materials (phenolics and alkyds). 

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