A multifunctional partially bio-based epoxy resin by renewable chitosan as reaction raw material: Shape memory effect, bonding property, excellent degradability, and toughening performance

To expand the variety of partially bio-based epoxy resins with superior performance and improve the efficiency of utilizing renewable raw materials, a chitosan-based bisphenol A epoxy resin (CBE) was successfully synthesized. With PA651 as the curing agent, the strain energy CBE/PA651 reached 15.11 MJ m −3 , which was higher than those of many typical ductile epoxy resins in comparative literature. The shape fixity and shape recovery rate of CBE/PA651 were 94.72 % and 98.74 %, respectively, demonstrating excellent shape memory effects. When CBE was used as wood adhesives, it exhibited a relatively high bonding strength and excellent water resistance, and the dry and boiling bond strength can exceed 4.08 MPa and 1.91 MPa, respectively. Simultaneously, CBE/PA651 can be completely degraded within 8 h at 90 °C, exhibiting excellent degradability. In addition, CBE was employed as a toughening agent for DGEBA/DDM. It was found that when the CBE content was 20 wt%, the elongation at break, the impact strength, and K IC of CBE/DGEBA/DDM reached their peak values of 8.55 %, 17.62 kJ m −2 and 1.75 MPa m 1/2 respectively, representing a significant increase of 101.65 %, 43.6 %, and 78.57 % compared to DGEBA/DDM. The toughening mechanism was revealed by SEM and crosslinking simulation networks.