Synthesis and properties of imidazole-blocked diisocyanates

✍ Scribed by Nasar, A Sultan; Subramani, S; Radhakrishnan, Ganga

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 115 KB
• Volume: 48
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199907)48:7<614::aid-pi192>3.0.co;2-v

✦ Synopsis

Imidazole-, 2-methylimidazole-and benzimidazole-blocked hexamethylene diisocyanate and isophorone diisocyanate have been prepared and characterized by elemental analyses, IR and NMR spectroscopy. The structure±property relationship of these adducts has been established by reacting with hydroxyl-terminated polybutadiene (HTPB). The cure rate of the adduct increases from the imidazole to 2-methylimidazole and to the benzimidazole-blocked adduct. Also, the cure rate of the adducts based on hexamethylene diisocyanate is higher than those based on isophorone diisocyanate. Simultaneous TGA/DTA results also con®rm this trend. The gas chromatogram of the imidazoleblocked isocyanate con®rms that the thermolysis products are blocking agent and isocyanate. The solubilities of the adducts have been measured in polyether and hydrocarbon polyols: the 2methylimidazole and benzimidazole-blocked hexamethylene diisocyanate adducts show higher solubility than the rest.