Replacing petro/fossil carbon by biobased renewable carbon derived from agricultural feedstocks offers the value proposition of (1) reduced carbon footprint, (2) supporting rural agrarian economy and improved food security, and (3) creation of "wealth" in the rural agriculture through manufacturing value-added industrial products. Our work reports on the synthesis of novel, scalable, and economically viable biobased polyols derived from soybean. Polyols find commercial use in the manufacture of polyurethane (PU) products, particularly flexible and rigid PU foams. Drop-in replacements of the currently used polyols with biobased polyols suffer from inferior performance properties with increasing biobased polyol content, high production cost, and incompatibility with petroleum-based polyols. The thesis also reports on the synthesis of novel polyols from meso-lactide and the production of value-added products therefrom. Meso-lactide is a co-product in the manufacture of polylactide (PLA). Polylactide (PLA) is the world's foremost completely biobased and fully compostable polymer with a production capacity of 140 kt/year by NatureWorks in Blair, NE and a 75 kt/year by Total Corbion PLA in Rayong, Thailand.The first section focuses on facile reaction chemistries to produce biobased polyols from a protein-carbohydrate residue derived from soybean meal or soymeal. The components of the soymeal were characterized to optimize processing options. The soymeal component was converted to polyols using transamidation chemistry, followed by a ring-opening reaction with carbonates. The process is cost effective with zero waste generated during the synthesis.In the second section, new biobased building blocks were synthesized from meso-lactide by reacting it with primary amines and alcohols. The ring-opening reaction of meso-lactide with an amino-alcohol produced diols containing amide and ester linkages in the backbone. These new biobased building blocks can be used to manufacture biobased polyesters and polyurethanes. Reacting meso-lactide with long-chain alcohols produces a diol containing ester and ether linkages with lower viscosity and hydroxyl value. This diol was further reacted with biobased dimer acid using polycondensation chemistry. A series of polyester-ether polyols with low viscosity and hydroxyl value (40-90 mg of KOH/g) were obtained which are suitable for applications in flexible PUF and coatings. The renewable carbon content of these polyols was 50-70% which can be increased to 100%.The third section focuses on evaluating the performance properties of PUF synthesized from biobased polyols. The biobased rigid PUF containing 20-50% of soymeal and lactide polyols were characterized for application as insulation materials in building and construction. The flexible PUF containing 10-50% of biobased polyol content were evaluated for automotive applications such as engine cover, car seat, and headrest.In the last section, reactive extrusion processing of lactide-dimer acid polyols with PLA was studied. The reactive blending of polyols with PLA increased the crystallinity of PLA by 600303-75% and decreased the glass transition temperature by 180303 °C. The elongation at break increased to 120%, and the impact strength was increased by 300%. The melt crystallization kinetics showed a reduction in the total crystallization time with increasing polyol content in PLA.To conclude the entire work, a series of cost-effective, scalable, diverse applications-oriented, and most importantly biobased, polyols were synthesized using inexpensive bioresources that have a potential for commercialization.
Read
