Sustainable 5-HMF to benzimidazole/furan-contained epoxy resins: Structural design and performance upgrade

A highly conjugated biobased liquid HPE monomer was fabricated from HMF. • The benzimidazole motif HPE contributes to a relatively mild curing behavior. • The HPE endows the resin with favorable mechanical properties and dimensional stability. • The HPE networks showed good solvent resistance and shape memory. • This strategy provided a tractable biocomposite fabrication. A novel bio-based epoxy monomer (HPE) bearing a rigid benzimidazole-furan skeleton was synthesized from 5-hydroxymethylfurfural (5-HMF). The activation energy for HPE-derived networks was relatively lower than that of the DGEBA counterparts, indicating favorable curing conditions. The cured HPE-thermosets exhibited exceptional mechanical properties. For instance, HPE/APB achieved good tensile strength (105.67 ± 13.43 MPa), flexural strength (125.43 ± 16.65 MPa), and impact strength (17.99 ± 1.10 kJ m −2 ). Moreover, the thermomechanical investigation also suggested its advantageous storage modulus of 3.55 GPa at 30 °C, which surpassed the petroleum-based DGEBA counterparts. Notably, HPE-networks displayed unique dimensional stability with a thermal expansion coefficient ranging from 87 to 115.4 ppm °C −1 below 200 °C. In contrast to DDM-cured thermoset, APB-cured networks also favored decreasing dielectric constant and loss. On the whole, the APB hardener outperformed the DDM in most cases. Furthermore, glass fiber-reinforced HPE composites demonstrated 90.8% peeling off in DMF under microwave-assisted conditions, making sustainable fiber recycling possible. This work provides a promising strategy for HMF-related renewable epoxy resins. Download: Download high-res image (147KB) Download: Download full-size image