Structure and morphology of a commercial high‐impact polypropylene in‐reactor alloy synthesized using a spherical Ziegler–Natta catalyst

Abstract

A commercial high‐impact polypropylene (hiPP) was fractionated by temperature‐gradient elution fractionation into nine fractions. All fractions were studied using Fourier transform infrared spectroscopy and differential scanning calorimetry. The amount of ethylene in the fractions was also determined. The results demonstrate that the ethylene–propylene statistical copolymer (or ethylene–propylene rubber, EPR) content in this hiPP is rather low and the amounts of ethylene–propylene segmented copolymer and ethylene–propylene block copolymer (that act as adhesive and compatibilizer between elastomeric phase and matrix, respectively) are negligible. Furthermore, the morphology of the resin was studied using scanning electron microscopy observations of microtome‐cut original and etched samples, which reveals that EPR particles are too large and their distribution inside the matrix is not uniform. Copyright © 2010 Society of Chemical Industry

Structure and properties of aβ-nucleated polypropylene impact copolymer

“…The impact resistance of these polymers is primarily due to the presence of discrete rubber particles, well distributed within the crystalline iPP matrix of products produced from these polymers. The size and distribution of these particles contribute to the final impact resistance, and these in turn are related to the amount and chemical composition distribution of the crystalline copolymers present in the final reactor alloy …”

Investigating Effects of Using Mixtures of Two External Electron Donors on Microstructure and Properties of Polypropylene/Poly(ethylene‐co‐propylene) in‐Reactor Blends Based on Ziegler–Natta Catalyst

“…To compare qualitatively the amount of ethylene content and crystalline sequences, the FTIR spectra of the fractions separated by xylene at 80, 90, and 100 8C and also the hexane hot soluble fraction were taken into account ( Figure 6). In the case of hexane hot soluble fraction the absorption at 840 and 998 due to methyl rocking modes which is associated with the three fold helical structure of iPP [33] and observable in Fr80, Fr90, and Fr100 is not visible. This means that the fraction is random copolymer.…”

“…The peaks at 1 020 and 1 100 do not appear usually in isotactic PP, but they have been seen in some author's works reporting the FTIR spectra of separated fractions from the PP/EPR blends. [32,33] According to Khafagy et al [34] these bands in the spectrum of PP homopolymer are related to the existence of an intermediate phase between crystalline and noncrystalline phases associated with the lamella structure. The bands are defined as regularity or helix bands.…”

Preparative TREF ‐ HT‐HPLC ‐ HPer DSC: Linking Molecular Characteristics and Thermal Properties of an Impact Poly(propylene) Copolymer

“…These two factors, the CCD (the chain structure, polymer type, and chain branching) and MMD, primarily influence the thermal properties (melting and crystallization behaviour) of such semi‐crystalline polymers. A variety of techniques has been reported to correlate the molecular characteristics of IPCs with their thermal and mechanical properties . Fractionation of the bulk sample by preparative TREF and further analysis of the separated fraction by conventional analytical techniques such as HT SEC, FTIR, 13 C NMR, and DSC has been found to be an effective method for the detailed analysis of such copolymer system .…”

“…A variety of techniques has been reported to correlate the molecular characteristics of IPCs with their thermal and mechanical properties . Fractionation of the bulk sample by preparative TREF and further analysis of the separated fraction by conventional analytical techniques such as HT SEC, FTIR, 13 C NMR, and DSC has been found to be an effective method for the detailed analysis of such copolymer system . Recently we reported on the difficulty associated with preparative TREF to accomplish a complete separation of the many different components due to co‐crystallization and co‐elution at similar temperature ranges.…”