Synthesis of polyols from vegetable oils and characterization of the produced polyurethanes

In this study, the production of flexible polyurethane from polyols obtained from different vegetable oils has been investigated. Canola, cotton, sunflower, corn, nuts, linseed, soybean and olive vegetable oils have been used in the production of polyol. Polyols based vegetable oil were obtained by applying processes of epoxidation, hydroxylation, neutralization and purification. In the polyols production from the vegetable oils, the effective parameters such as hydrogen peroxide and reaction time on the hydroxyl numbers have been optimized. It was observed that the hydroxyl numbers of polyols produced from different vegetable oils are different from one another. Rheological properties of both vegetable oils and the polyols obtained from those vegetables oils were determined at different values of temperatures. The correlations between the viscosities and the temperature have been developed for both the vegetable oils and the polyols obtained from those vegetable oils. Mechanical strength, density, thermal conductivity, pore structure, flammability, crosslink structure, thermal stability of the produced polyurethane has been characterized. In addition, the effects of marble, melamine factory wastes and some inorganic additives on the properties of polyurethane were investigated. The vegetable oil based polyols obtained from canola, sunflower, corn, cotton, hazelnut and soybean oil gave more positive results in polyurethane production. The cross-linking structure, mechanical strength, thermal conductivity and porosity were negatively affected in the polyurethanes produced from linseed and olive oil based polyols. It was observed that the parameters such as the temperature, humidity, raw material, additives, catalysts, mixing speed and pressure should be kept at constant at the optimum values in vegetable oils-based polyols and polyurethane synthesis since in order to obtain the maximum yield, each parameter is required to be at a suitable value. Formulation was prepared for the production of polyurethane by adding suitable catalysts, initiators and additives to vegetable oil based polyols. First, the additives are added into the vegetable oil-based polyols at room temperature and then the mixture was homogenously stirred. The size of the additives is important for the homogeneity of the mixture. The mixtures of water, silicon and amine catalysts were prepared by taking the optimized proportion of each one in a different vessel. Isocyanate and stannous octoate were added in the optimized proportions for polyurethane production. The additives, water, silicon, amine, stannous octoate and isocyanate components were added to the vegetable oil-based polyol, respectively. The effects of types of oils on the polyurethane material were investigated by using vegetable oil-based polyols having the same hydroxyl number while keeping all other effective parameters constant. The cell structure, crosslink structure and mechanical properties of polyurethane produced by using different vetegatable oil-based polyols at the same conditions were compared each other. With aim of investigating the effect of hydroxyl numbers on the polyurethane, polyols, produced from canola oils, with different hydroxyl numbers have been used in the production of polyurethane while keeping the other effective parameters constant. It was observed that the pores of the obtained polyurethane were homogeneous, open and strong cross-linked while the number of hydroxyls was at the optimum values in vegetable oils-based polyols. In the production with polyols having low hydroxyl number, pores are closed and soft, while in that with the polyols having high hydroxyl numbers increase fragility and decrease mechanical strength. The effect of the particle size of the additive on the thermal conductivity was also investigated. It was observed that as the particle diameter of the used additive increased, the thermal conductivity of the polyurethane also increased. Key Words: Vegetable oils, Vegetable oil based polyol, Polyurethane.