In order to improve elongational viscosity of polypropylene, allowing its use in a wide range of applications, different samples of branched polypropylene have been produced by reactive extrusion and evaluated by different techniques. It is known that the long chain branching (LCB) can act as a nucleating agent in the crystallization process. This is confirmed by differential scanning calorimetry (DSC), optical microscopy, and crystallization analysis fractionation (CRYSTAF), where an increase in the crystallization temperature can be observed when comparing linear and branched samples. In the chemical composition distribution profile of the analyzed samples, it is possible to see differences in the amount of crystallized material among the branched PP samples and it is possible to correlate it with the long chain branching content and distribution, measured by Triple Detector Gel Permeation Chromatography (3D-GPC), using the Mark-Houwink plot (MH Plot), conformation plot, and gpcBR methodology. A decrease in dissolution temperature, and an increase in soluble fraction is observed by temperature rising elution fractionation (TREF) at increasing LCB content in the polymer samples. These results indicate that the presence, amount, or distribution of long chain branching affects the crystallization kinetics and the crystal morphology. CRYSTAF and TREF show a good correlation with LCB content measured by GPC.
In this work, three polypropylene impact copolymers (ICPs) with different chemical compositions are characterized using gel permeation chromatography (GPC) with triple detection: infrared (IR), viscometer (VIS) and multi angle light scattering (MALS), crystallization analysis fractionation (CRYSTAF), thermal gradient interaction chromatography (TGIC), nuclear magnetic resonance (13C‐NMR) and atomic force microscopy (AFM). The average rubber composition is determined and correlated with the ICP morphology and final mechanical properties. GPC‐IR is used to analyze the ethylene content and distribution along the molecular weight distribution (MWD). The amorphous phase composition distribution is analyzed as a function of temperature by TGIC. The microstructure and morphology of ICP amorphous phase are studied in detail by 13C‐NMR, GPC 3D, TGIC, SEM and AFM allowing to differentiate the samples.
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