The Preparation Of Renewable Polyols And Its Application In Polyurethane Materials

In this paper, first fatty acids were prepared from the hydrolysis of acidic oil which was a kind of residue after the refining of soybean oil. Then, the obtained fatty acids were reacted with maleic anhydride to prepare maleic anhydride-based adducts. Finally, the renewable polyester polyols were prepared by the esterification between maleic anhydride-based adducts and diethylene glycol. The obtained renewable polyester polyols were used to prepare polyurethane rigid foams, and the relationship between structure and properties of foams was also studied.First, the effect of reaction time and catalyst dosage on the acidic oil hydrolysis process was studied, and the components of fatty acid were characterized by gas chromatography (GC) and nuclear magnetic resonance (1H NMR). The results showed that fatty acids contained 20.2wt% oleic acid and 59.0wt% linoleic acid. Maleic anhydride-based adducts were prepared by the reaction between fatty acids and maleic anhydride, and the effect of maleic anhydride dosage and the reaction temperature on the "ene" reaction was also studied. The results showed that with the increase of maleic anhydride dosage and the reaction temperature, the extent of "ene" reaction between double bonds in fatty acids and maleic anhydride increased, while the content of oligomers also increased. In the esterification, when the [OH]/[COOH] was 4:1 and the acid value of maleic anhydride-based adducts was 354mg KOH/g, the renewable polyester polyols with a hydroxyl value of 293mg KOH/g and a acid value of 2.6mg KOH/g were prepared successfully.Using n-pentane as blowing agent, polyurethane rigid foam were prepared by substituting parts of polyether polyol from obtained renewable polyester polyols, and the effect of renewable polyester polyols content on the cell structure and physical properties of PU foam was investigated. The results showed that due to the primary hydroxyl groups existed in the renewable polyester polyols, the foaming rate of PU foam increased as the increase of renewable polyester polyols content. Compared to the PU rigid foam prepared from pure polyether polyol, when the polyester polyols content was 20-30wt%, the prepared PU rigid foams showed a better compressive strength and thermal stability, meanwhile, the cell size and thermal conductivity of PU rigid foams decreased.