Date of Award
Spring 5-12-2017
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
First Advisor
(rgupta@pittstate.edu) Dr. Ram Gupta
Second Advisor
(pkahol@pittstate.edu) Dr.Pawan Kahol
Third Advisor
(ksiam@pittstate.edu) Dr. Khamis Siam
Fourth Advisor
(cneef@pittstate.edu) Dr. Charles Neef
Keywords
Bio-waste, Bio-based starting chemicals, Polyurethane, Supercapacitor, Flame retardant, High Electrochemical performance
Abstract
Bio-based polyol for rigid polyurethane (PU) foams and porous structured carbon as an electrode material for supercapacitors were synthesized from readily available biowaste precursor (orange peel) as an alternative to currently used petroleum-based starting materials. Synthesized bio-based polyols were characterized using FTIR, GPC, hydroxyl number, and viscosity measurements. These analyses indicated that intended bio-based polyol was obtained via thiol-ene chemistry with a high yield. Rigid PU foams prepared from bio-based polyol exhibited density around 35 kg/m3, maintained a regular cell structure with uniform cell distribution, closed cell content over 90%, and excellent compressive strength of ~230 kPa, suggesting its suitability for thermal insulation applications. To improve the fire safety of rigid PU foams, dimethyl methyl phosphonate was added and fire resistance properties was regulated according to the horizontal burning test. Foams containing only 2 pbw of DMMP showed reduction in burning time by ~83% compared to the neat foam (without DMMP). TGA analysis indicated that the improved flame retardancy could be attributed to the release of DMMP at the temperature range of 100 °C to 250 °C.
Porous carbon prepared through KOH activation and pyrolysis demonstrated its potential as a high performing electrode material for energy storage. It was found that surface area and pore size of carbon can be controlled by varying the precursor to the KOH ratio. The specific surface area significantly increased with the increasing amount of KOH, reaching specific surface area of 2,521 m2/g for 1:3 mass ratio of precursor/KOH. However, the 1:1 mass ratio of precursor/KOH displayed the optimum charge storage capacitance of 407 F/g, owing to the ideal combination of micro-mesopores and higher degree of graphitization. The capacitive performance of the orange peel derived electrode was found to be varied with the electrolyte employed. The orange peel derived electrode in KOH electrolyte displayed the maximum capacitance and optimum rate capability. The orange peel derived electrode maintained above 100% capacitance retention during the 5,000-cyclic test and identical charge storage over different bending status. The fabricated supercapacitor device delivered high energy density (100.4 mWh/cm2) and power density (6.87 W/cm2), along with improved performance at elevated temperatures. This thesis demonstrates biowaste can be facilely converted into valuable starting materials for synthesis of polymers and energy storage devices.
Recommended Citation
Akurana Gamaralalage, Charith K. R., "BIOWASTE DERIVED RIGID POLYURETHANE FOAMS AND SUPERCAPACITORS: A RENEWABLE AND SUSTAINABLE ALTERNATIVE FOR PETROCHEMICALS" (2017). Electronic Theses & Dissertations. 374.
https://digitalcommons.pittstate.edu/etd/374
