Development of castor oil-based paints with anti-radiation and antimicrobial properties

Abstract

Agricultural commodities are increasingly being utilized in the chemical industry as alternative raw materials to petrochemicals. In the polymer industry, vegetable oils are used to produce oleo-based polymers which find application in the paint and coatings industry as chief ingredients. Among the vegetable oils, castor oil has gained much interest because it is non-edible and constitute of ~90% ricinoleic acid which offers flexible modifications. In this research, castor oil was used to synthesize a drying oil, polyurethanes and epoxy resins, and to achieve this objective, castor oil had to undergo certain chemical modifications, which include: epoxidation, ring opening, dehydration and polymerization. The synthesized paints were then blended with Ag and TIO2NPs to impart anti-radiation and antimicrobial properties. The synthesized paints were characterized by FTIR and 1HNMR to confirm the occurrence of the reactions and also to evaluate the reaction conversion. Rheology studies were done to determine the usability of the synthesized materials as coatings. A study was performed on the drying time of the drying oil, polyurethanes and epoxy resins paint formulations under atmospheric conditions. Further tests were done to test for the anti-radiation and antimicrobial properties. A 100% conversion was obtained for epoxidation reaction for the following reaction conditions: 35 °C temperature, 4wt% catalyst amount , 1:2 ( castor oil: H2O2) ratio and 32 hrs reaction time. For the ring opening reaction a conversion of ~ 70% was obtained when the reaction was done with H2O as the nucleophile and HClO4 as catalyst. The temperature was100°Cwith a mass ratio of 1:18:0.2 ( ECO:H2O: HCLO4) for 48 hrs. A conversion of 43% for DCO and 53% for RCO was attained at the following reaction conditions: 240 °C, 0.1 g NaHSO4 and 120 min reaction time. The synthesized CO-based polyurethanes had a 6 hrs drying time when a 2k catalyst was added, while the drying time for epoxy resins was 6 days. The lowest drying time for the drying oil was 2 days. It was found that Streptococcus sp growth inhibition can be obtained at a low concentration of Ag/AgTiO2 NPs within the paints. For the anti-radiation properties, it was found that paint sample with NPs TiO2++ showed no changes at all after UV irradiation for 90 minutes. With the chemical modifications and incorporation of the right additives, paints were obtained that can be used practically