Date of Award
Spring 5-13-2023
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
First Advisor
Dr. Ram K. Gupta, rgupta@pittstate.edu
Second Advisor
Dr. Khamis Siam, ksiam@pittstate.edu
Third Advisor
Dr. Charles-Jody Neef, cneef@pittstate.edu
Fourth Advisor
Dr. Anuradha Ghosh, aghosh@pittstate.edu
Keywords
Polyurethane, Rigid Polyurethane Foam, Flame Retardants, Bio-based Materials, Thermal Insulation, Castor Oil
Abstract
Fossil fuel derivatives in the polyurethane industry are gradually being replaced with environmentally friendly alternative bio-based resources. Vegetable-oil-based polyols are emerging bio-based resources that can decrease cost competitiveness in polyurethane markets, reduce environmental impacts, and meet the urgent need for green and sustainable development strategies. Among this, interest is the use of castor oil to make polyurethane because of its inedibility and the fact that it contains many functionalizable chemical groups. However, the poor thermal stability and low load-bearing capacity of castor-oil-based rigid polyurethane foam limits its application. Two methods were used to address these limitations: (i) more hydroxyl groups were introduced through simple chemical methods to increase the crosslinking density and (ii) four eco-friendly flame retardants were introduced to increase the thermal stability of polyurethane foams. Meanwhile, the influence of the flame retardant type and amount of flame retardant that would yield the best results was studied. Thus, phosphorus, nitrogen, and carbon-based flame retardants were introduced (10.2 wt.%) to the castor oil based-based polyurethane matrix.
The test results revealed that the prepared castor oil-based polyurethane without flame retardants have 38.16 kg/m3 of apparent density, 94% closed cell content, and compression strength of 257 kPa. Therefore, this research findings provide a bio-based, low-cost, and effective alternative for rigid polyurethane foam production. Regardless of the addition of flame retardants, the shape of the free-rise foams maintained their structure, suggesting that there is acceptable compatibility between the flame retardants and castor oil-based polyurethane matrix. The physicochemical and mechanical properties, cell morphology, and thermal stability results further confirmed this observation. Flame retardancy and thermal stability increased with an increase in the flame-retardant percentage. Castor oil-based rigid polyurethane foams with phosphorus-based flame retardants exhibited good thermal properties but comparatively poor mechanical properties, whereas castor oil-based rigid polyurethane foams with nitrogen-based flame retardants exhibited excellent mechanical properties and relatively poor thermal properties. Interestingly, castor-oil-based rigid polyurethane foams with carbon-based flame retardants outperformed these two types of flame retardants. Thus, this study suggests that carbon-based flame retardants can significantly reduce the flammability of castor-oil-based polyurethanes without considerably affecting their mechanical properties.
Recommended Citation
Abeysinghe Arachchilage, Prasadi, "EVALUATION OF PROMISING ECO-FRIENDLY FLAME RETARDANTS FOR BIO-BASED RIGID POLYURETHANE FOAMS BASED ON MODIFIED CASTOR OIL" (2023). Electronic Theses & Dissertations. 640.
https://digitalcommons.pittstate.edu/etd/640
