| Phase separation is important for polyurethanes (PU). In order to know factors affecting the phase separation in polyurethanes, a phase separation study for a series of samples was conducted using different polymer characterization techniques. Phase separation should be more complete for the polyurethanes with aromatic hard segments and aliphatic soft segments because of higher incompatibility between the aromatic hard segment and the aliphatic soft segment. However, phase separation becomes more complete for polyurethanes with aliphatic hard segments due to higher mobility of the hard segments and lower viscosity of the system during the reaction and post cure process.; Soybean oil products are renewable, environmentally friendly materials. Much research has been conducted in order to find new uses for soybean oil products in industry. The second part of the dissertation describes curing epoxidized soybean oil (ESO) with isocyanates and their derivatives. Poly(isocyanurate-oxazolidones) (PISOX) formed from ESO and isocyanate have been found to have poor mechanical properties. Incorporation of a polyether polyol into the reaction system not only provides crosslinked poly(isocyanurate-oxazolidone-urethanes) (PISOXU) polymers with good thermal stability and useable mechanical properties, but also accelerates the overall reactions. Fourier transform infrared spectroscopy analysis and differential scanning calorimetry analysis were used to evaluate the rates of reactions, identify the polymer compositions as well as propose the reaction schemes and mechanisms. These two kinds of techniques, together with mechanical analysis, thermogravimetric analysis, wide angle X-ray diffraction analysis and scanning electron micrography analysis were used to characterize the obtained polymers. |
