Antioxidant efficiency versus structure

Abstract

Abstract Antioxidant efficiency versus structure was investigated using rate of carbonyl formation at 110 and 170°C of a 20 mil plaque of polyethylene containing 0.01 weight % additive. This study indicates that the following are important in phenolic and amine antioxidants: The number of H. atoms available: Antioxidant efficiency is increased by adding a second hydroxyl group as well as by introducing a methylene bridge. The number and location of substituents: Alkyl substitution of the phenolic ring is an important factor in stabilization. Groups which decrease the strength of the NH bond increase the effectiveness of amine antioxidants. Solubility: The less compatible the antioxidant, the poorer its stabilizing action. Volatility: Many stabilizers are ineffective at high temperature because of volatilization. Bridge between rings: A sulfide bridge can be equivalently substituted for a methylene bridge. The need for stabilization of the radical formed after removal of H: This stabilization could occur via; Hydrogen bonded chelates, resonance and steric hindrance.