Techno-economic Analysis and Life Cycle Assessment of Biomass-Derived Polyhydroxyurethane and Non-Isocyanate Polythiourethane Production and Reprocessing

Non-isocyanate polyurethanes (NIPUs) show promise as more sustainable alternatives to conventional, isocyanate-based polyurethanes (PUs). In this study, polyhydroxyurethane (PHU) and non-isocyanate polythiourethane (NIPTU) production and reprocessing models inform the results of a techno-economic analysis and a life cycle assessment. The profitability of selling PHU and NIPTU is rationalized by identifying significant production costs, indicating that raw materials drive the costs of PHU and NIPTU production and reprocessing. After stepping along a path of process improvements, PHU and NIPTU can achieve minimum selling prices (MSPs) of 3.15 USD kg-1 and 4.39 USD kg-1, respectively. Depolymerization yields need to be optimized and polycondensation reactions need to be investigated for the reprocessing of NIPUs into secondary (2°) NIPUs. Of the NIPUs examined here, PHU has a low depolymerization yield and NIPTU has a high depolymerization yield. Fossil energy use, greenhouse gas (GHG) emissions, and water consumption are reported for the bio-based production of PHU, NIPTU, 2° PHU, and 2° NIPTU and compared with baseline values for fossil-based PU production. There are options for reducing environmental impacts which could make these pathways more sustainable. If barriers to implementation are overcome, 2° NIPUs can be manufactured at lower cost and environmental impacts than virgin NIPUs.