Influence of amine‐terminated additives on thermal and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) cured epoxy

Abstract

The present work accounts for the influence of aromatic amide oligomers on the inherent brittleness of cured epoxy. Aromatic and aliphatic amine‐terminated amide oligomers have been prepared by condensation polymerization using isophthaloyl dichloride and two different amines. The oligomers have been characterized using Fourier transform infrared spectroscopy and wide angle X‐ray diffraction analysis. Diglycidyl ether of bisphenol A (DGEBA) is cured with a diamine (4,4′‐oxydianiline) by using different weight ratio of oligomers. The FTIR of cured epoxy shows ring opening by the disappearance of oxirane ring peak at 913 cm−1, whereas X‐ray diffraction shows its amorphous phase in the cured state. The thermogravimetric analysis of the resultant composites shows that the thermal stability slightly decreases (467–454 °C) with increasing the oligomer content from 5 to 25 wt %, whereas the mechanical parameters (Young's modulus, tensile strength, impact strength, and elongation at break) increase with increase in the oligomer content. DMA shows lower tanδ values for aliphatic amine‐terminated oligomers for cured epoxy. Two‐phase surface morphology is observed through scanning electron microscopy. Owing to their high mechanical and thermal properties, aromatic amides have observed to greatly influence the mechanical properties of cured epoxy, particularly its brittleness. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48404.

Mechanical characterization of different epoxy resins enhanced with carbon nanofibers

“…The introduction of new molecular chains of different lengths, with pendant groups, aliphatic or aromatic elements, vary many physicochemical and solid-state properties of the composites. For example, heterocyclic and aromatic curing reagents are responsible for higher temperature stabilities than their aliphatic amine alternatives [25]. An increment in the flexible amine content decreases the tensile and flexible strength related to a reduced crosslinking density [26].…”

Synthesis of a hyperbranched polyamide oligomer containing DOPO for simultaneously enhancing the flame retardance and glass transition temperature of epoxy resin

“…The flame retardant is expected to overcome flammability and increase T g of EP. PA, as a thermoplastic engineering resin, is usually used to improve the properties of EP or EP composite due to its excellent performance 22,23 . Therefore, in this paper, a hyperbranched PA oligomer containing DOPO (HPD) was synthesized using ethylene diamine tetraacetic acid (EDTA) and DOPO functionalized with diamines as starting materials.…”

Plasticizing effect of biodegradable dipropylene glycol bibenzoate and epoxidized linseed oil on diglycidyl ether of bisphenol A based epoxy resin

“…Due to this approach cross‐link density was adjusted by two‐phase separation phenomena and resulted in high elongation at break (>100%) and still acceptable tensile strengths. Recently in another study, Baig et al 28 modified epoxy curing agent with two different amine terminated additives and studied its effects on mechanical and thermal properties of epoxy polymer. They have found that aromatic amine terminated polymers imparted better overall mechanical properties than aliphatic amide polymers.…”