Summary Heterophasic poly(propylene) copolymers obtained by sequential polymerization are multi‐component products formed by a crystalline matrix of poly(propylene) and an ethylene‐propylene rubber phase. Some crystalline polyethylene and poly(ethylene‐co‐propylene) are formed in the rubber synthesis step by copolymerization of ethylene and propylene. These multi‐component systems present a complicated microstructure and heterophasic morphology. In this study, two heterophasic copolymers with the same total amount of rubber but different composition and molecular weight, were thoroughly analyzed. The morphology was evaluated by SEM and AFM techniques. The complexity of the system required some attention in the fractionation methodology to perform an accurate interpretation of results and different methodologies of fractionation, especially for obtaining PE fractions as free of PP as possible, were performed in order to better characterize the crystalline polyethylene fractions in the copolymers. Preparative TREF was used to obtain fractions for further analysis by 13C‐NMR, DSC and GPC. Also samples were submitted to Cross Fractionation Chromatography (CFC). Results obtained by the different methodologies were compared.
Summary The grafting of HDPE and LLDPE with itaconic acid (AIt) was made by reactive extrusion using the peroxide 2,5‐dimethyl‐2,5‐di(tert‐butyli) peroxy hexane (trigonox 101) as initiator. The graft efficiency was evaluated using FTIR to identify bands of carbonyl groups in the polymer. It is influence on the addition of itaconic acid in the structure of the polymer chain was evaluated using CRYSTAF and microcalorimetry, where it was show that the incorporated acid causes a narrow crystallization profile and the decrease of the percentage of the soluble fraction at 30 °C. The polymers were fractionated by molecular weight and chemical composition to check the distribution of the AIt incorporation, the percentage of AIt was quantified in each fraction by FTIR, and it was show that the incorporation of AIt occurred homogeneously in all the chains.
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