S.A. Direction Centrale des Recherches, Laboratoire Central, 31 0 rue de Ransbeek, B-1 120 Bruxelles, Belgium SYNOPSIS 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°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 0-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). 0 1995 John Wiley & Sons, Inc.

SYNOPSISA set of anhydride-grafted polypropylenes was collected from various companies. They were studied in light of our recent results on polypropylene melt grafted with maleic anhydride.' This work confirmed that an important decrease of the anhydride content is recorded on heating or washing, due to the elimination of free, ungrafted products, respectively, by sublimation of maleic anhydride and by polymaleic anhydride solubilization. The deconvolution of the infrared spectra of washed anhydride-grafted polypropylenes (PP-g-MA) revealed two types of grafted anhydride: succinic anhydride form and polymaleic anhydride form. All in all, four forms of anhydride functions were detected two grafted and two free, each being either on monomeric or polymeric forms. Nevertheless, one PPg-MA (Hercoprime) can be distinguished by its very high grafting level. This polymer is therefore discussed in more detail. Finally, all the present results are discussed with regard to the principal applications of the PP-g-MA as a blend compatiblizer or as an adhesion promoter.

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This work deals with the study of PAmXD,6/PP‐g‐MA blends [poly(meta‐xylylene adipamide)] and (maleic‐anhydride‐functionalized‐polypropylene) blends. Compatibilization occurs during the blending of the components in a Brabender plastograph at 265 ± 5°C and at a mixing rate of 45 rpm. Kinetic data from the literature indicate that the rate of amine/anhydride reaction is much faster than the rate of amide/anhydride reaction. This interpretation is confirmed by the use of model systems constituted of PAmXD,6 and pyromellitic dianhydride or of PP‐g‐MA and meta‐xylylene diamine. Infrared analyzes of extracted nodules of PAmXD,6/PP‐g‐MA blends also confirm the extent of the imidization and show that the length of the PAmXD,6 blocks is lower than the free PAmXD,6 one. Segregation mechanisms during the compatibilization are discussed to explain this observation. The structure of the copolymers was deduced from those results and from the previous characterizations of PP‐g‐MA and PAmXD,6. It consists in a block of PP linked with some blocks of PAmXD,6. The average number of PAmXD,6 blocks depends on the average length of the poly(maleic anhydride) functionality carried on by PP‐g‐MA. © l997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 901–915, 1997

This work deals with the study of the phase inversion phenomenon in blends of poly(m‐xylylene adipamide) and maleic anhydride functionalized polypropylene (PAmXD,6/PP‐g‐MA blends) processed in a Brabender plastograph at 265 ± 5°C and 45 rpm. The viscosity of the components has been modelized by the Brabender torque and the phase inversion composition was determined by means of a solvent dispersion technique (SDT). The compatibilization, i.e., the amount of copolymer in the blend, does not modify the phase inversion location. The phase inversion composition is determined early during the process and is weakly or even not at all affected by further modification of viscosity ratio of the components versus mixing time. This work demonstrates that the only key parameter of the phase inversion composition is the viscosity ratio of the components at the first stage of the mixing process. An empirical equation linking volume fraction ratio for the phase inversion composition and the square root of the viscosity ratio of the components is proposed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 917–925, 1997