STUDIES ON ANTIOXIDANTS .3. -DI-TERT-BUTYL-4-HYDROXYPHENYL)METHYLENE]HYDRAZINE CARBOTHIOAMIDE AS A MELT STABILIZER FOR UNSTABILIZED POLYPROPYLENE

Polypropylene's high processing temperatures initiate thermal oxidativ e degradation and loss of physical properties. Antioxidants protect po lymers through the severe conditions of processing and fabrication and also through end use. Small amounts of antioxidants like 2,6-di-tert- butyl-4-methylphenol and di-tert-butyl-4-hydroxyphenyl)methylene]-hydr azine carbothioamide are shown to be effective in protecting isotactic polypropylene (IPP) against thermooxidative degradation. -Di-tert-but yl-4-hydroxyphenyl)methylene]hydrazine carbothioamide was melt compoun ded with IPP using a twin screw extruder. The melt flow index of the e xtruded sample was measured. The extruded granules were injection mold ed to get specimens suitable for testing mechanical properties, such a s heat deflection temperature, Izod impact strength, tensile strength, tensile modulus, flexural strength, and flexural modulus. -Di-tert-bu tyl-4-hydroxyphenyl)methylene]hydrazine carbothioamide was found to be an effective melt stabilizer for unstabilized polypropylene. (C) 1995 John Wiley & Sons, Inc.