Ageing of polyol premixes used in the production of rigid polyurethane-polyisocyanurate
Polimery 1996, No 4, 222
The ageing behaviour of polyol premixes was investigated with Rokopol TG-500 replaced by N
'-di(2,5-dioxa-7-hydroxy-8-chlorooctylo)urea (DOM). The viscosity and density data and the activation energy of the viscous flow of these premixes measured immediately after preparation were compared with those observed after the premixes were stored for 3000 hours in tightly closed containers. At 20—40°C premixes are Newtonian fluids. After having been stored for 3000 hours at 20°C, with or without DOM, the premixes had an unaffected viscosity and energy of activation of viscous flow. Control samples of rigid PUR-PIR foams prepared from fresh and 3000 hold premixes revealed similar useful properties. DOM resulted in improved properties of rigid PUR-PIR foams: the premixes were stable and, after having been stored for 3000 hours at room temperature, could be used for foam preparation purposes.
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