Water-Blown Polyisocyanurate Foams From Vegetable Oil Polyols

摘要

Polyols with the hydroxyl value OHV from 290 to 318 mg KOH/g are synthesized from rapeseed,sunflower seed,flaxseed,or coconut oils by the way of their:(1)transesterification with triethanolamine or(2)amidization with diethanolamine.The influence of water as the blowing agent on the storage stability of the polyol premix system is assessed from values of the polyol premix system pH,acid value,and variations in such parameters as cream and gel time.Water-blown polyisocyanurate(PIR)foams(150>II<300;II-isocyanate index)characterized by good mechanical characteristics,dimensional stability at 70°C and at relative humidity RH=95% as well as by a very low water absorbance,are obtained.The optimal physical and mechanical properties of water-blown PIR foams are achieved at the isocyanate index values 150-200.The values of the solubility parameter delta and normalized cohesion energy.E_(coh.norm).for the groups and blocks,incorporated in the polymer matrix,are calculated.A detailed experimental analysis has proved that the water-blown PIR foams from vegetable oil polyols possess competitive physical and mechanical properties to those exhibited by the traditional petrochemical origin foams.The optimal physical and mechanical properties suitable for practical applications,are achieved at the isocyanate index values 150