A Review on Morphology, Chemical and Physical Structure of Polyurethane Foam Coatings

Abstract

Today, more than 75 percent of total polyurethane consumption in the world is in the form of foam, and a significant proportion of these foams are used in coatings in various industries. The production and consumption of these types of coatings have a growing trend due to reasonable price, making lightweight structures, excellent adhesion to substrates, quick and easy curing at ambient temperatures, high durability, ability to cut and form into various types and shapes, their ease of application, optimal mechanical properties such as high resilience, compressive strength and etc. Polyurethane foam coatings are used in building and transportation industries as thermal and acoustic insulation coatings, flooring, wall buffers in community halls, and so on. Two reactions of gelation and blowing carried out simultaneously in foam admixture. The final properties of foams depend entirely on the structure, stability and geometry of the foam cells which are function of the relative rate of these two reactions. So controlling of reaction rates in the direction of the optimal final product are essential. The controlling factors of these two reactions include of temperature, the presence of an amine or organic-metal catalyst and isocyanate index. The most important factor determining the properties of polyurethane foam is its cellular structure. In this review study, comprehensive information was collected about the role of materials, chemical reactions during foam formation, physical and chemical structure of cells and the factors affecting the final properties of cellular coatings