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Keywords:

polypropylene, beta-scission, melt functionalization, maleic anhydride, poly(maleic anhydride), ethylene-propylene copolymers, high-density polyethylene, bulk functionalization, reaction-kinetics, degradation, rubber, melt, peroxides, extrusion, Science & Technology, Physical Sciences, Polymer Science, POLYPROPYLENE, BETA-SCISSION, MELT FUNCTIONALIZATION, MALEIC ANHYDRIDE, POLY(MALEIC ANHYDRIDE), ETHYLENE-PROPYLENE COPOLYMERS, HIGH-DENSITY POLYETHYLENE, BULK FUNCTIONALIZATION, REACTION-KINETICS, DEGRADATION, RUBBER, MELT, PEROXIDES, EXTRUSION, 0303 Macromolecular and Materials Chemistry, 0306 Physical Chemistry (incl. Structural), 0912 Materials Engineering, Polymers, 3403 Macromolecular and materials chemistry, 3406 Physical chemistry

Abstract:

This work deals with the molecular characterization of maleic anhydride melt-functionalized polypropylene (PP-g-MA). The functionalization mechanism, the nature, the concentration, and the location of grafted anhydride species onto the polypropylene chain are discussed. The polypropylene functionalization was performed using a pre-heated Brabender Plastograph (190 degrees C, 4 min of mixing time). Several concentrations of maleic anhydride and organic peroxide were used for this study. In those experimental conditions, the organic peroxide undergoes an homolytic rupture and carries out a polypropylene tertiary hydrogen abstraction. The resulting macroradical undergoes a beta-scission leading to a radical chain end which reacts with maleic anhydride. When a termination reaction occurs at this first step a succinic type anhydride chain end is obtained. However, oligomerization of maleic anhydride is found to occur more frequently leading to poly( maleic anhydride) chain end. Concentration of both anhydride types and minimal length of the grafted poly(maleic anhydride) were determined. A fraction of maleic anhydride does not react with polypropylene or homopolymerize leading to nongrafted poly(maleic anhydride). (C) 1995 John Wiley and Sons, Inc.