Abstract
In this study, three sorts of polyols were successfully synthesized from castor oil using a Dean-Stark quick, eco-friendly and high-efficiency method. For this purpose, castor oil was epoxidized in the presence of two types of catalysts including γ-alumina and formic acid, named as ECOAl and ECOF, respectively. Epoxidized castor oils were then characterized by use of hydrogen nuclear magnetic resonance (H-NMR) and oxirane oxygen content analysis. The relative percentages of conversion double bond to oxirane were obtained 96% and 74% for ECOAl and ECOF, respectively. Ring opening reaction of ECOAl was performed by two types of saponified castor oil as well as castor oil in a system equipped with Dean–Stark apparatus. The synthesized polyols were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), viscometer and OH number evaluation. The material obtained in this research is a candidate to be intended in synthesis of polyurethane for coating applications.
Highlights
After replacing water with petroleum solvents and producing water-based polymers, the researchers attempted to replace other petroleum components of polymer products with renewable materials
The peak at 5.28-5.5 ppm which belongs to the presence of C=C bond in castor oil disappeared after epoxidation and the peak of epoxy group observed at 2.9-3.2 ppm
Epoxidation of castor oil was performed by two different catalysts, either γ-alumina or formic acid
Summary
After replacing water with petroleum solvents and producing water-based polymers, the researchers attempted to replace other petroleum components of polymer products with renewable materials. Castor oil is one of the most important triglycerides, which is a viscous, pale yellow, non-volatile and non-drying oil [15] that Because of its medicinal value has been known since ancient days [16] This vegetable oil has peculiar characteristics, such as its fatty acid composition (90% of ricinoleic acid). In order to produce vegetable oil-based polyol, the hydroxyl groups should be introduced through appropriate chemical modifications on either the carbon-carbon double bonds or the ester functionally present in triglycerides [20]. Epoxidation of vegetable oils, followed by oxirane ring-opening is one of the most common methods to introduce the hydroxyl groups on the carbon-carbon double bonds. The present work reports for the first time the synthesis three types of castor oil-based polyols using a short, eco-friendly and high-efficiency method. Properties of obtained polyols were investigated by ATR-FTIR, GPC, DSC, viscometer and OH number evaluation
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