Synthesis and Characterization of a Polyurethane Phase Separated to Nano Size in Epoxy Polymer

Epoxy resins are widely applicable in industries such as aircraft, automobiles, coatings, and adhesives because of their good chemical resistance and excellent mechanical and thermal properties. However, on an external impact, the crack propagation of epoxy polymers weakens the overall impact resistance of the materials. Therefore, many impact modifiers have been developed to reduce the brittleness of epoxy polymers. Polyurethanes as an impact modifier can improve the toughness of polymers. Although it is known that polyurethanes are phase-separated in the polymer matrix after curing, connecting polyurethanes to the polymer matrix has been problematic for enhancing the mechanical properties of polymers. In this study, we introduced epoxy functional groups into polyol backbones, which is different from other studies that focused on modifying capping agents to achieve a network structure between the polymer matrix and polyurethane. We confirmed the molecular weight of the prepared polyurethane with gel permeation chromatography. Moreover, the prepared material was added to the epoxies to evaluate the changes in the mechanical and thermal properties of the materials. Furthermore, we conducted tensile, flexural strength, and impact resistance measurements. The experimental results are discussed in detail.