Date of Award
Master of Science (MS)
Dr. Ram Gupta
Dr. Khamis Siam
Dr. Timothy Dawsey
Dr. John Franklin
The current shift from solely depending on petroleum sources to seeking renewable alternatives is due to their fast depletion, spike in prices, and the need to reduce our carbon footprint. For instance, the polyurethane industry currently calls for renewable and less toxic polyols and isocyanates for their synthesis over the traditionally used ones. To tackle an aspect of this matter, this work investigates the generation of polyol from sunflower oil, and further probes their use in rigid foams, one of the widely utilized polyurethanes. Epoxidation and ring-opening reactions were used to convert the sunflower oil into a more reactive form, and tests like iodine value, hydroxyl number, Fourier-transform infrared (FT-IR) spectroscopy, and gel-permeation chromatography (GPC) were performed to validate the synthesis of the intermediates and polyol.
Following this, an easy one-step technique was used to efficiently mix all the foam components in a short time. On the other end of this work, the high flammability of rigid foams is a concern, and strategic efforts to combat it were investigated. Here, non-halogenated flame retardants (FRs) -- aluminum hypophosphite (AHP), dimethyl methylphosphonate (DMMP), and expandable graphite (EG) -- were added into the rigid foam formulation, and their individual flame-retardant and other mechanical effects on the sunflower-based foams were investigated. For an acceptable mechanical, insulating, and reduced flammability of the foams, their density, closed cell content, compression, horizontal burning, and other characteristics were investigated.
On average, all the foams fell in a 30-55 kg/m3 density range with compressive strengths greater than 160 kN/m2 and the highest recorded around 290 kN/m2. With the exception of some high concentrations of the respective flame retardants (FRs) tested, all the foams had closed cells greater than 90%. It was found that the burning time of the foams reduced significantly from 79 seconds in the pure foams, to 5 seconds in AHP-5 (13.61 wt.% of AHP), 2 seconds in DMMP-5 (13.61 wt.5% of DMMP), and 6.5 seconds in EG-5 (13.61 wt.% of EG). The maintained and improved properties of the rigid foams in this work suggested the usefulness of sunflower polyol in the foam synthesis, the effective flame-reducing characteristics of the FRs, and the possibility to explore other renewable sources for polyurethane synthesis.
Asare, Magdalene, "SUNFLOWER OIL-BASED POLYOL IN FLAME-RETARDANT RIGID POLYURETHANE FOAMS" (2022). Electronic Theses & Dissertations. 398.