Isocyanate-terminated polyethers toughened epoxy resin: Chemical modification, thermal properties, and mechanical strength

Abstract

The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers (ITPE) was investigated. The progress of the reaction and the structural changes during modifi cation process were studied using FTIR spectroscopy. The studies support the proposition that TDI (tolylene diisocyanate) acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It is indicated the glass transition temperature (T g ) of systems was lower than the T g of pure epoxy resin and overfull ITPE separated from the modifi ed epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the fl exural strength of the cured modifi edepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m 2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy (SEM) studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identifi ed.

Effect of Chitosan Loading on the Morphological, Thermal, and Mechanical Properties of Diglycidyl Ether of Bisphenol A/Hexamethylenediamine Epoxy System

“…Zhang [10] explained the advantages and disadvantages of using reactive liquid rubbers, functionally terminated engineering thermoplastics, reactive ductile diluents, and inorganic and hybrid particles as modifiers to improve fracture toughness. Cai et al [11] conducted experiments on DGEBA epoxy resin with isocyanate terminated polyethers (ITPE) modifier showing that the thermal stability decreases with the introduction of ITPE while the impact and flexural strength of the cured modified epoxy increase with ITPE loading. Brooker et al [12] incorporated thermoplastic toughener poly(ether sulfone) copolymer into epoxy system reporting that the ultimate tensile strength and fracture toughness increased with increasing thermoplastic content.…”

“…Over the past decade, various attempts to enhance the toughness of epoxy system have been carried out by incorporating fillers into epoxidesto produce a variant form of epoxy resin coupled with different chemical compositions. Review of the literature shows that majority of the previous work employed thermoplastic, rubber, and elastomer compounds as toughening agents in epoxy systems [2][3][4][5][6][7][8][9][10][11][12][13].…”