| Summary: | Deriving chemicals from renewable feedstock has become a necessity to reduce dependency on petroleum, which release carbon dioxide when burned and aggravate the global warming and ocean acidification. This work offers a potential alternative - bark extractives based epoxy resin - to petro-based conventional epoxy. Our results showed successful epoxidation of bark extractives after reaction with epichlorohydrin. The newly synthesized epoxy (E-epoxy) can replace 50% of petroleum-based epoxy (P-epoxy) and the blend system displayed thermal stability and tensile strength comparable to neat P-epoxy, which demonstrates a great promise in using bark extractives as a substitute for bisphenol A (BPA). An examination of reaction parameters showed that the E-epoxy monomer can be synthesized with high yield and reactivity using spray-dried extractives as substrates, a dioxane/water combination as solvent, and tetrabutylammonium hydroxide as the ring-opening catalyst. An examination of numerical parameters showed the maximum yield with minimum epoxy equivalent weight was achieved after 4.5 hours reaction time with sodium hydroxide to hydroxyl value molar ratio of 3.4 at a reaction temperature of 80 °C. The thermal properties of E-epoxy were studied using TGA, FTIR, and Py-GC/MS, and a new thermal degradation mechanism was proposed. Additionally, nanocellulose fibres (NCFs) were incorporated to enhance E-epoxy’s mechanical performance. Based on an adjusted curing schedule, an E-epoxy/P-epoxy/NCFs composite with high strength, ductility, thermal stability, and sustainability was developed. With 10% E-epoxy, the toughness of neat epoxy resins improved 84 %; after incorporating NCFs, the tensile strength and modulus of composites increased approximately two- and four-fold, respectively. The maximum degradation peak of the composites was 24 °C higher than for neat epoxy resins. Overall, bark extractives exhibit great promise to replace petro-based BPA; incorporating NCFs into E-epoxy/P-epoxy blending system is an effective method to develop a strong and sustainable bio-nanocomposite. Ph.D.
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