Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

James R. Davidson,Ankur Bajpai,Colin Robert

doi:10.3390/applmech2020023

James R. Davidson, Ankur Bajpai + Show 1 more

Open Access

https://doi.org/10.3390/applmech2020023

Copy DOI

Journal: Applied Mechanics	Publication Date: Jun 21, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: University of Edinburgh

Abstract

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

Highlights

The main objective of this work was to compare blends of bisphenol-Abased epoxy and various multifunctional epoxies cured with anhydride hardener, with regards to mechanical properties, fracture mechanics and thermal properties of the obregards to mechanical properties, fracture mechanics and thermal properties of the obtained tained modified systems
For all modified epoxy systems, the maximum tensile strength and modulus were obtained at 10 wt.%—see Figure 6 for the representative stress–strain response of the 10 wt.%
The greater degree of crosslinking and increased length, contribute to the increased tensile strength over the reference epoxy resin. This performance improvement may be partly attributed to a degree of increased polymer chain entanglement. Another possible reason for higher strength and modulus comes from the introduction of additional rigid, polar groups with higher functionality in comparison to the diglycidyl ether of bisphenol-A (DGEBA) system, which increases the crosslink density within the system

Summary

Introduction

Epoxy resins are widely used as matrices in composite materials for structural applications in the automotive and aerospace industries. This is due to their high strength and stiffness, as well as their excellent thermal and chemical resistance properties. The addition of soft fillers like rubber or thermoplastics to thermosets plasticize the structure, enhancing fracture toughness whilst lowering stiffness, strength, and glass transition temperature [1,2,3]. Improvements in strength and modulus have been reported where ceramic-based nanoparticles have been dispersed prior to curing [4,5,6,7,8,9].

Objectives

Results

Conclusion