Fully bio-based furan/maleic anhydride epoxy resin with enhanced adhesive properties

Abstract

Epoxy resins are widely used in a variety of application fields, thanks to their good mechanical strength, chemical resistance and adhesion to several substrates. Nowadays, the quite majority of epoxy resins are based on derivatives of bisphenol A (BPA), which poses serious health concerns. This issue is pushing the research towards suitable bio-based alternatives to this product, being furan-based epoxies very promising in this respect. In a previous work, 2,5-bis[(oxiran-2-ylmethoxy)methyl]furan (BOMF) was cured with methyl nadic anhydride (MNA), and successfully used as tinplate coating. Herein, in a view of increasing the sustainability of these epoxy resins, we have replaced MNA with maleic anhydride (MA), which can be derived from vegetable feedstocks, thus obtaining a fully bio-based epoxy resin. This latter has then been used as adhesive for carbon fiber-reinforced thermosetting plastics (CFRP). The curing process of the resin was monitored by differential scanning calorimetry (DSC) and chemo-rheological analysis. The results highlighted the significantly higher reactivity of BOMF towards MA compared to the diglycidyl ether of BPA (DGEBA). The crosslinked samples were characterized in their thermal, mechanical and adhesive properties. In comparison to DGEBA/MA and BOMF/MNA, BOMF/MA showed higher ultimate strain and slightly lower glass transition temperature, tensile modulus and ultimate strength. Interestingly, BOMF/MA displayed outstanding adhesive strength on CFRP joints, outperforming the DGEBA-based counterpart by three times. Indeed, by properly selecting the anhydride curing agent, a highly ductile fully bio-based material was developed for high performance adhesive applications. The overall results demonstrate that the properties of BOMF-based epoxy resins can be tailored to meet technical and safety requirements of downstream applications, representing a sustainable alternative to traditional systems containing DGEBA.

Use of Bio-Epoxies and Their Effect on the Performance of Polymer Composites: A Critical Review

“…Moreover, bio-content can be integrated into epoxy systems using natural polysaccharides, such as D-glucose [ 48 ]. Further, as food waste-based feedstocks it should be mentioned the furan , which presents a compelling potential as substitute for phenyl building blocks derived from petroleum in epoxy thermosets (see Section 2.2.2 ) [ 49 , 50 , 51 , 52 , 53 ]. This organic aromatic compound, composed of four carbon atoms and one oxygen, can be derived from bagasse, the residual material from sugar cane processing, as well as from corn cobs or other biomass sources.…”

“…It was made up of furan , which can be synthesized from sugars (e.g., glucose and xylose) via catalytic conversion. The use of maleic anhydride (MA) as a bio-based curing agent, derived from furan and furfural, led to a completely bio-based epoxy resin [ 50 ]. The value of such bio systems, measured by DSC analysis, resulted in being 29% lower than DGEBA-MA epoxy due to their inherent reduced chain rigidity.…”

High-Impact Epoxy Resins with Superior Hydrophobicity Toughened by Epoxy Functionalized Poly(olefin-alt-maleimide) Derivatives

“…Taking 1-hexene as a model α-olefin, the poly(1-hexene-alt-MAH) (PHMA) copolymer was efficiently synthesized, which can serve as a polymeric curing agent for EPs. However, as a common kind of curing agent for EPs, anhydride derivatives can dramatically increase the crosslinking density, 37 consequently leading to the decline of toughness. Chen et al 38 reported a solvent-free pathway to convert anhydride-functionalized copolymers to imide-functionalized copolymers through a simple heat treatment.…”

Synergistic Dual-Cure Reactions for the Fabrication of Thermosets by Chemical Heating

“…The candidate thermoset system we chose for this study is epoxy/anhydride, which has gained recent popularity due to its sustainability evaluation compared to more conventional epoxy systems. − As an example, Wang et al recently published on a bioderivable epoxy/anhydride resin, named P oly- E ster C ovalent A daptable N etwork (PECAN), which was designed in analogy to a conventional epoxy/amine formulation used for wind blades which demonstrated up to 40% lower GHG emissions and recyclability while maintaining all requisite performance metrics . Despite the benefits of this system, sluggish initiation at temperatures below 80 °C coupled with long cure times (>5 h) may be prohibitive to its widespread adoption by industry.…”