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

Abstract

Epoxy resins are widely applicable in the aircraft, automobile, coating, and adhesive industries because of their good chemical resistance and excellent mechanical and thermal properties. However, upon external impact, the crack propagation of epoxy polymers weakens the overall impact resistance of these materials. Therefore, many impact modifiers have been developed to reduce the brittleness of epoxy polymers. Polyurethanes, as impact modifiers, can improve the toughness of polymers. Although it is well known that polyurethanes (PUs) are phase-separated in the polymer matrix after curing, connecting PUs to the polymer matrix for enhancing the mechanical properties of polymers has proven to be challenging. 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 PU. We confirmed the molecular weight of the prepared PU via gel permeation chromatography. Moreover, the prepared material was added to the epoxies and the resulting mechanical and thermal properties of the materials were evaluated. Furthermore, we conducted tensile, flexural strength, and impact resistance measurements. The addition of PU to the epoxy compositions enhanced their impact strength and maintained their mechanical strength up to 10 phr of PU. Furthermore, the morphologies observed with field emission scanning electron microscopy and transmission electron microscopy proved that the PU was phase separated in the epoxy matrix.

Development of a Novel Biobased Polyurethane Resin System for Structural Composites

“…Tests were performed in flexural mode. The T g of the PUR resin systems was taken at the temperature value of the maximum of tan δ, Tα [ 42 , 46 ].…”

Bio-Based Polymer Developments from Tall Oil Fatty Acids by Exploiting Michael Addition

“… where ν e is the cross-link density (mol·cm −3 ), E ′ is the tensile storage modulus (MPa), R is the gas constant (8.314 m 3 ·Pa·K −1 ·mol −1 ), and T is the temperature corresponding to the storage modulus value into the rubbery plateau (K) [ 52 , 53 , 54 , 55 ].…”

“…The following supporting information can be downloaded at: , Table S1: Characteristics (glass transition temperatures (T g ) by DMA, tensile (Young’s) modulus (E 1 ), tensile strength, and cross-link density (v e )) of the selected polymers for comparison. References [ 5 , 15 , 39 , 43 , 52 , 53 , 56 , 68 , 74 , 75 ] are cited in Supplementary Materials .…”

Effect of the biobased polyols chemical structure on high performance thermoset polyurethane properties

“…The sample dimensions were 2.2 × 5 × 50 mm 3 . The Tg of the PUR resin systems was taken at the temperature value of the maximum of tan δ, Tα [38,39].…”