Characteristics of polyurethane adhesives with various uretonimine contents in isocyanate and average alcohol functionalities

Polyurethane adhesives are found in a variety of applications. To ensure durability and functionality, a polyurethane adhesive is required to possess good adhesive properties and thermal stability. In this study, polyurethane adhesives were fabricated using isocyanate and polyols of various type and functionality (f_av). It was found that peel strength of an adhesive is strongly related to the f_av of a polyol and uretonimine content. At high uretonimine content, the probability of forming hydrogen bonded component increases and as a result the adhesive's peel strength increases. At high f_av and molecular weight of a polyol, an adhesive's wettability decreases so does its adhesion to a substrate. Therefore, designing for a functional adhesive, high uretonimine content and low f_av of polyol are desired. Thermal stability of a polyurethane adhesive also improves with uretonimine content.