Design of Sustainable Materials by the Transformation of Biorefinery Derived Waste Biomass into Biobased Polymeric Resins: Synthesis, Characterization, Applications

Abstract

Polymeric resins (PRs) are one of the most versatile materials, with a wide range of application fields. However, the synthesis of these polymeric resins predominantly relies on the precursor derived from the petroleum refinery that utilizes crude oil as feedstock, posing environmental, economic, and human health concerns at various points of its life cycle. Biorefinery offers the potential to replace fossil fuel-based products by converting renewable biomass into multiple products, hence maximizing biomass's value. Lignocellulosic biomass derived from plant re-sources and municipal solid waste has been proven as the most abundant one among the diverse biomass resources. The present research aimed to develop biobased polymeric resins by replac-ing or substituting conventional monomers/chemicals with biorefinery-derived biomass for ap-plications such as wood adhesives, 3D printing of structural materials, and functional coating for controlled release of fertilizers. In Chapter 2, lignin recovered from kraft biorefinery (L-KB) and two bio-oils, prepared from laboratory scale solvent liquefaction of lignin (BO-SL/L) and fast pyrolysis of pinewood (BO-FP/PW), respectively, have been used to substitute 50% (w/w) of phenol in novolac phenol-formaldehyde (NPF) resin system. The adhesive derived from lig-nin showed the highest tensile strength (3.46 ± 0.55 MPa). This indicates that the lignin derived from kraft biorefinery is a potential substitute for phenol in NPF resin systems for wood adhe-sive applications. In Chapter 3, biobased novolac phenol-formaldehyde (BNPF) resin was de-veloped by partially replacing petroleum-based phenol and formaldehyde with lignin derived from kraft biorefinery-and modified kraft biorefinery-derived lignin, respectively. The chemical modification of lignin was performed through a periodate oxidation process using sodium peri-odate (NaIO4) as an oxidizing agent. The bonding performance tests indicated that BNPF resin adhesives have high adhesion strengths (>0.7 MPa). The outcome of this research provides a new way to utilize bio feedstock such as lignin for synthesizing biobased wood adhesives. In Chapter 4, bio-oils produced from hydrothermal liquefaction (HTL) of municipal sewage sludge (MSS) at different processing conditions have been utilized as a natural filler for pMDI wood adhesive formulation. For each MSS bio-oils, three different loading levels (MSS Bio-oil/pMDI weight ratio: 0.18, 0.33, and 0.54) were selected as a treatment to understand better the chemi-cal interaction of the MSS-Bio-oil/pMDI adhesive formulation with the wood substrate. Overall, the bio-oil produced under a nitrogen atmosphere demonstrated significant potential to reduce the usage of petroleum-derived pMDI while maintaining good bonding performance. In Chapter 5, a biobased novolac phenol-formaldehyde (BNPF) resin was successfully developed by par-tially substituting phenol with a bio-oil obtained by fast pyrolysis of pinewood biomass. The curing kinetics of BNPF resin cured with hexamethylenetetramine (HMTA) was studied using the differential scanning calorimetry (DSC) method. The thermal curing kinetics were studied through model-fitting approaches. The Kamal model is employed and proved a best-fitting model in describing the curing behavior of the BNPF/HMTA resin. In the final chapter, bi-obased polyurethane (BPU) was synthesized out of lignin derived from kraft biorefinery. Then, BPU coatings were utilized to coat urea fertilizer to achieve a controlled release of nutrients. The nutrient-release behavior of developed coated fertilizers was systematically studied in wa-ter and soil environments. The experimental results indicated that the coating material derived from all lignin was beneficial for slowing down the nutrient release. This study highlights the potential of lignin in developing controlled-release fertilizers for sustainable agriculture.