220
6.4 Oxidation
Triglycerides-based oils are mainly restricted to their oxidation stability by the
degree of unsaturated double bonds. In several reactions like oxidation, unsaturated
carbon-carbon bonds serve as active sites [59]. Most triglyceride-based oils contain
unsaturated fatty acids and are vulnerable to oxidation. The higher the unsaturation
level, the more double bonds the oil will become sensitive to oxidation. The oxidation mechanism of castor oil has been well investigated and a famous representation
of the oil is shown in Fig. 6 [60, 61]. The development of free radicals initiates castor oil oxidation. The elimination of hydrogen atom in the methylene group from
next to a double bond can easily lead to free radical formation. Free reacts rapidly
with oxygen to form a peroxy radical. Radical peroxy can attack another lipid molecule to remove a hydrogen atom to form a hydroperoxide and another free radical,
propagating the oxidation process [62]. Castor oil oxidation is taken at a temperature of about 80–130 °C in the presence of blowing air or oxygen with or without a
catalyst, and mixing is required for the formation of clear and viscous oxidized or
blown castor oil with varying viscosity. This process is a mixture of oxidation and
polymerization; therefore, it is called oxidative polymerization. Oxidized castor oils
are excellent non-migrating, non-volatile cellulosic resin plasticizers, poly (vinyl
butyral), polyamides, shellac, and natural and synthetic rubber. Since blown castor
oil high acid value, imparting oil and solvent resistance to produce the high viscosity materials with increased viscosity, and compatibility and decreased solubility.
This oil is used as excellent pigment grinding media and as an ink foundation, lubricating oils, plasticize in adhesives, hot melts, and hydraulic oils [6, 9, 63, 64].
OH
O
O
O
OH
OH
O
O
O
O
Expoxidized castor oil
O
OH
O
O
O
O
O
O
O
OH
OH
Castor oil
H 2 O 2 /H+
H 3 PO 4
CH 3 COOH
Fig. 6 Epoxidation of castor oil
S. Dhanuskar et al.
6.4 Oxidation
Triglycerides-based oils are mainly restricted to their oxidation stability by the
degree of unsaturated double bonds. In several reactions like oxidation, unsaturated
carbon-carbon bonds serve as active sites [59]. Most triglyceride-based oils contain
unsaturated fatty acids and are vulnerable to oxidation. The higher the unsaturation
level, the more double bonds the oil will become sensitive to oxidation. The oxidation mechanism of castor oil has been well investigated and a famous representation
of the oil is shown in Fig. 6 [60, 61]. The development of free radicals initiates castor oil oxidation. The elimination of hydrogen atom in the methylene group from
next to a double bond can easily lead to free radical formation. Free reacts rapidly
with oxygen to form a peroxy radical. Radical peroxy can attack another lipid molecule to remove a hydrogen atom to form a hydroperoxide and another free radical,
propagating the oxidation process [62]. Castor oil oxidation is taken at a temperature of about 80–130 °C in the presence of blowing air or oxygen with or without a
catalyst, and mixing is required for the formation of clear and viscous oxidized or
blown castor oil with varying viscosity. This process is a mixture of oxidation and
polymerization; therefore, it is called oxidative polymerization. Oxidized castor oils
are excellent non-migrating, non-volatile cellulosic resin plasticizers, poly (vinyl
butyral), polyamides, shellac, and natural and synthetic rubber. Since blown castor
oil high acid value, imparting oil and solvent resistance to produce the high viscosity materials with increased viscosity, and compatibility and decreased solubility.
This oil is used as excellent pigment grinding media and as an ink foundation, lubricating oils, plasticize in adhesives, hot melts, and hydraulic oils [6, 9, 63, 64].
OH
O
O
O
OH
OH
O
O
O
O
Expoxidized castor oil
O
OH
O
O
O
O
O
O
O
OH
OH
Castor oil
H 2 O 2 /H+
H 3 PO 4
CH 3 COOH
Fig. 6 Epoxidation of castor oil
S. Dhanuskar et al.