Synthesis and characterization of hindered-phenol-containing amine moieties as antioxidants for polypropylene copolymers



(4-Ethylphenyl)-3,5-ditertiarybutyl-4-hydroxybenzylamine, 1-phenyl-4-(3,5-ditertiarybutyl-4-hydroxybenzyl)piperazine, and 1-(3,5-ditertiarybutyl-4-hydroxybenzyl)piperidine were synthesized and characterized, and their performance in polypropylene copolymer (PPCP) was tested by multiple extrusions in a Brabender plasticorder. The thermooxidative stability of PPCP was assessed by the measurement of oxidative induction time at 200 ± 1°C, and the thermal stability was assessed by observation of the change in the melt flow rate. A comparative study of the synthesized antioxidants with the commercially available antioxidant 2,6-ditertiarybutyl-4-methylphenol was made. The presence of phenolic and amino groups influenced the performance of the antioxidants. The performance of the antioxidants influenced the thermal stability of the PPCP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1097–1103, 2004