ABSTRACT
Polyols based on vegetable oils are increasingly becoming viable alternatives to the petrochemical polyols. However, their structure varies from molecule to molecule introducing an additional factor, which might affect the properties. In order to examine the effect of structure on properties and avoid this cause of heterogeneity we have used model oils having three (triolein) and six (trilinolein) double bonds as well as linseed oil (which contains more than six double bonds) and converted them to polyols by inserting an OH group per double bond. While this conversion was almost quantitative with triolein, the hydroxylation of trilinolein and linseed oil was not complete, giving lower functionality than predicted. The structure of the polyols was characterized by spectroscopic, physical and chemical methods. They were reacted with MDI to give polyurethanes with different crosslinking densities, which were determined from equilibrium swelling in toluene. While trifunctional oil (triolein)-based polyol gave a rubbery material at room temperature, trilinolein and linseed oil based polyurethanes had glass transition temperatures at 60 °C and 76 °C, respectively. Increasing crosslinking density caused an increase in modulus and tensile strength and decrease in elongation at break.
