(558g) Influence of Substitution and Position of Furan Ring within Epoxy Resins

Epoxy resins are used in a wide range of applications including fiber-reinforced composites and electrical components. The range of applications results from epoxy resins having favorable properties like high strength and good dimensional stability without producing side products during cure. However, epoxy resins are highly flammable because of the molecular structure limiting their use in certain applications. Most epoxy resins are bisphenol A (BPA) based, which is a known human endocrine disruptor and sourced from petroleum. BPA is also known to have low thermal stability. Therefore, there is a need to find a suitable and renewable alternative to BPA that can increase thermal stability. Suitable phenolic derivatives have been researched and furan was identified as a promising candidate. Furan is a five-membered, heterocyclic compound from polysaccharides found in biomass wastes like corn cobs and rice husks. Furan-based compounds have been used as high temperature resins like poly(furfuryl alcohol) in the foundry industry. Incorporating furan moieties into epoxy resins has the potential to impart increased thermal stability while being sourced from renewable materials.

In this work, three furan-based amines were epoxidized to create furan-based glycidyl amine epoxy resins. The substitution on the furan ring and position of the furan ring within the polymer network were investigated. The first epoxy resin contained a monosubstituted, pendant furan ring in the network. The second epoxy resin still contained a pendant furan ring within the network, but the furan ring was disubstituted. The third resin also contained a disubstituted furan ring, but the furan ring was linked within the network. The epoxy monomers were characterized using carbon and hydrogen Nuclear Magnetic Resonance (¹³C- and ¹H-NMR) and Gel Permeation Chromatography (GPC). Monomers were homopolyermized without the need for an additional catalyst because of the tertiary amine present in glycidyl amines. The homopolymerization was confirmed using a heated stage Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). Additionally, the participation of furan in the network formation was investigated using FTIR and DSC. The thermal stability and thermomechanical properties of the resulting polymers were tested using Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA). A structure-property relationship of the substitution and position of the furan ring within the network was developed. The epoxy with the disubstituted and linked furan ring showed the highest char yield at 1000 °C (44 %) and glass transition temperature (T_g=130 °C). The improved properties were a result of the furan ring being linked in the network and disubstituted.