Polyvinyl chloride thermal stabilizer from high-acid crude rice bran oil: a non-food utilization of rice bran oil☆

Abstract

Rice bran is a source of healthy oil which contains antioxidants and essential vitamins. Without pretreatment, the rapid activity of lipase enzyme causes the oil to contain high amounts of free fatty acids, making it unsuitable for edible purposes. In such cases, utilizing it for chemicals becomes an option. This study presents the synthesis of reverse ester organotin (REOT) as a thermal stabilizer for polyvinyl chloride (PVC) from high-acid crude rice bran oil. The success of the synthesis was confirmed through FTIR spectroscopy. The stabilizing effect of the resulting REOT was examined through dehydrochlorination and two-roll mill tests. Both tests confirmed that the obtained REOT could significantly increase the thermal stability of PVC. At relatively low dosages of 0.5 to 1.5 phr (parts per hundred resin), it maintained the initial color of PVC for up to 45–60 min when rolled under heating at 190 °C. Additionally, its thermal stabilizing effects were comparable to REOT derived from tall oil fatty acid (TOFA), a conventional raw material. The impact on flowability of PVC melt was also statistically similar to that of REOT from TOFA. Overall, crude rice bran oil fatty acid has been proven to be an effective alternative raw material for REOT based PVC thermal stabilizer.

Keywords

• free fatty acid
• heat stabilizer
• polyvinyl chloride
• reverse ester organotin
• rice bran oil