The use of hydrocarbons or R134A as alternate blowing agents to R141B will require changes in the raw materials commonly used to make rigid foams.Specifically,there must be changes in the structure of polyols to improve the solubility of hydrocarbons or R134A.The use of today's aromatic polyester polyols is gaining momentum in Europe.Pentane is not soluble in these polyols.The most common approach taken to use these materials has been to emulsify the hydrocarbon in the polyol mixture,and depend on the emulsion stability to make quality foams.This requies the use of additives the dilute the aromatic content of these products,and reduce the processing window for the systems.
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