Shelf Life Stability of Prepolymers

Due to its selective action, p-nitrobenzoylchloride and similar acylchlorides can be usefully employed as stabilizers for polyurethane prepolymer systems. Any basicity in the polyol can be neutralized and sufficient excess added to prevent crosslinking occurring during storage of the prepolymer. This overcomes undue increase in viscosity and facilitates processing. Typical proportions used are 0 01-01 mol per litre of prepolymer. 

Compound Metal (%) Gelation times (min at 7(fC) Prepolymer Reaction  

Courtesy of P. Wright A. P. C. Cumming, (1969). Solid Polyurethane Elastomers. Maclaren and Sons, London. 

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