Characterization of the microstructure of impact polypropylene alloys by preparative temperature rising elution fractionation

Xue, Yanhu; Fan, Yandi; Bo, Shuhui; Ji, Xiangling

doi:10.1016/j.eurpolymj.2011.05.016

Cited by 32 publications

(19 citation statements)

References 25 publications

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“…Alternatively, chain scission at or near the EP junctions in these copolymers could, as was shown earlier, “release” more highly crystallizable “polyethylene‐like” materials which could crystallize at higher temperatures (and as such be present in those TREF fractions). Segmented ethylene–propylene copolymers with long ethylene sequences act as compatibilizers that will enhance interfacial adhesion between random copolymer regions and propylene homopolymer regions and enhancing impact strengths . Breaking down of these copolymers will therefore affect the low temperature impact properties of the HEPCs.…”

Section: Resultsmentioning

confidence: 99%

“…This doublet is not seen for samples MS002 and MS005 (this corresponds to the NMR analysis which show a decrease in the long EEE sequences). From literature assignments can be made for most if not all the absorption peaks. The absorption peaks at 998 cm −1 and 841 cm −1 are caused by methyl‐rocking vibrations associated with isotactic (crystalline) polypropylene, whereas the peak at 973 cm −1 can be associated with the methyl rocking vibrations of atactic (amorphous) polypropylene.…”

Section: Resultsmentioning

confidence: 99%

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The effect of controlled degradation on the molecular characteristics of heterophasic ethylene–propylene copolymers

Swart

Reenen

2014

J of Applied Polymer Sci

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A commercial heterophasic ethylene–propylene copolymer (HEPC) produced by Sasol Polymers using a Ziegler‐Natta catalysed gas‐phase process was vis‐broken (controlled degradation) to various degrees by making use of an organic peroxide. The effects of the amount of vis‐breaking on the molecular characteristics and physical properties were subsequently studied by making use of preparative Temperature Rising Elution Fractionation (p‐TREF), Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), High Temperature Size Exclusion Chromatography (HT‐SEC), and deposition of the SEC fractions via the LC Transform Interface (SEC‐FTIR). It was found that by increasing the amount of organic peroxide, the molecular characteristics of the heterophasic copolymer are severely affected and hence influence the physical characteristics of the polymer dramatically. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41783.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The effect of controlled degradation on the molecular characteristics of heterophasic ethylene–propylene copolymers

Swart

Reenen

2014

J of Applied Polymer Sci

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“…Solution crystallization‐based techniques like temperature rising elution fractionation (TREF) have been largely utilized for the analysis of CCD of many polyolefin systems . Preparative TREF (being tedious and time consuming) separates and concentrates minor constituents within the bulk sample.…”

Section: Introductionmentioning

confidence: 99%

“…These materials were not observed in the analyses of the bulk samples. Fractions collected from preparative TREF can be further analyzed by other analytical techniques …”

Section: Introductionmentioning

confidence: 99%

On the Homogeneity of Metallocene Ethylene–Propylene Copolymers as Investigated by Multiple Fractionation Techniques

Phiri

Dimeska²,

Pasch

2015

Macro Chemistry & Physics

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The chemical heterogeneity of ethylene–propylene copolymers by multiple fractionation techniques is addressed. Three metallocene copolymer samples with different ethylene contents, ranging from 30 to 50 mol% are analyzed using bulk methods to confirm their molecular heterogeneity. In a second step, the samples are fractionated by temperature rising elution fractionation (TREF) to obtain fractions at 30, 60, 90, and 130 °C. These fractions are subsequently analyzed regarding their thermal and molecular properties. Differential scanning calorimetry, crystallization analysis fractionation, and high‐temperature high performance liquid chromatography (HT‐HPLC) results reveal that the TREF fractions collected at 130 °C are mainly due to polypropylene homopolymer, which is rather unexpected considering the high ethylene contents of the bulk samples. Most importantly, HT‐HPLC reveals a remarkably high chemical heterogeneity of the fractions and thus the bulk samples. Solution 13C NMR provides the comonomer contents and sequence distributions of the fractions. These indicate that the same TREF fractions from different samples have distinctively different chemical compositions.

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“…In addition to the CCD profile, CEF can also provide information on chain branching by using IR detection . Even though CEF is superior to CRYSTAF and TREF in terms of analysis time and resolution, it cannot address the non‐crystallizable part of the sample, which constitutes the amorphous or lower temperature‐soluble fractions . The crystallizable and the amorphous fractions can be analyzed, however, when an interaction (adsorption) based separation technique is used.…”

Section: Introductionmentioning

confidence: 99%

Chemical Composition Separation of EP Copolymers by CEF and HT‐SGIC: Crystallization versus Adsorption

Cheruthazhekatt

Mayo

Monrabal

et al. 2013

Macro Chemistry & Physics

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Preparative temperature rising elution fractionation (prep TREF) suffers from co‐crystallization effects and, therefore, cannot provide reliable chemical composition distribution (CCD) information. This limitation can be overcome when prep TREF is combined with further fractionation methods such as crystallization elution fractionation (CEF) or high‐temperature solvent‐gradient‐interaction chromatography (HT‐SGIC) as a new approach. By CEF, significant amounts of (co‐crystallizing) amorphous ethylene‐propylene (EP) copolymer are identified in semicrystalline TREF fractions of a heterophasic ethylene/propylene copolymer (HEPC). Complete compositional fractionation with no influence of crystallization effects is accomplished by HT‐SGIC. Prep TREF–HT‐SGIC is found to be the most selective and suitable method for the fast and complete CCD analysis of such complex EP copolymers with CEF providing complementary information.

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Characterization of the microstructure of impact polypropylene alloys by preparative temperature rising elution fractionation

Cited by 32 publications

References 25 publications

The effect of controlled degradation on the molecular characteristics of heterophasic ethylene–propylene copolymers

The effect of controlled degradation on the molecular characteristics of heterophasic ethylene–propylene copolymers

On the Homogeneity of Metallocene Ethylene–Propylene Copolymers as Investigated by Multiple Fractionation Techniques

Chemical Composition Separation of EP Copolymers by CEF and HT‐SGIC: Crystallization versus Adsorption

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