Epoxidized and Maleinized Hemp Oil to Develop Fully Bio-Based Epoxy Resin Based on Anhydride Hardeners

The present work aims to develop thermosetting resins using epoxidized hemp oil (EHO) as a bio-based epoxy matrix and a mixture of methyl nadic anhydride (MNA) and maleinized hemp oil (MHO) in different ratios as hardeners. The results show that the mixture with only MNA as a hardener is characterized by high stiffness and brittleness. In addition, this material is characterized by a high curing time of around 170 min. On the other hand, as the MHO content in the resin increases, the mechanical strength properties decrease and the ductile properties increase. Therefore, it can be stated that the presence of MHO confers flexible properties to the mixtures. In this case, it was determined that the thermosetting resin with balanced properties and high bio-based content contains 25% MHO and 75% MNA. Specifically, this mixture obtained a 180% higher impact energy absorption and a 195% lower Young's modulus than the sample with 100% MNA. Also, it has been observed that this mixture has significantly shorter times than the mixture containing 100% MNA (around 78 min), which is of great concern at an industrial level. Therefore, thermosetting resins with different mechanical and thermal properties can be obtained by varying the MHO and MNA content.