Liquid chromatography at critical conditions of polyethylene

Mekap, Dibyaranjan; Macko, Tibor; Brüll, Robert; Cong, Rongjuan; deGroot, A. Willem; Parrott, Al; Cools, P.J.C.H.; Yau, Wallace W.

doi:10.1016/j.polymer.2013.08.040

Cited by 31 publications

(24 citation statements)

References 33 publications

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“…Meanwhile, the interest in the liquid chromatography of macromolecules at elevated temperatures is due to the fact that some polymers, e.g. polyolefines, are dissolved at elevated temperatures only, therefore the chromatographic analysis of such polymers can be performed only with the help of a high-temperature chromatography [3,9,10]. Thus, it is now recognized that temperature is an important tool to optimize chromatographic parameters, such as retention, selectivity and efficiency, particularly for macromolecules [2,6,[10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on adsorption and chromatography of polystyrene macromolecules

El’tekov¹

2018

sorpchrom

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Study of the effect of temperature on the parameters of adsorption and liquid chromatography of molecules and macromolecules constantly attracts the attention of specialists. The potential benefits of elevated temperature column, particularly enhanced kinetic and transport properties, which are based on the reduction of mobile phase viscosity and increase the diffusion of analyte at high temperature, began to be actively used for the rapid analysis of molecules and macromolecules by chromatographic methods in recent years. It is now recognized that temperature is an important tool to optimize chromatographic parameters, such as retention, selectivity and efficiency, particularly for macromoleculesThe effect of temperature on adsorption and liquid chromatography of polystyrene macromolecules on silicas has been investigated by static and .chromatographic methods. The sign and value of the temperature adsorption coefficient depend on many factors, namely, the chemical nature of the solvent, the chemical structure of macromolecules and adsorbent surface chemistry. Thus temperature elevation in the chromatographic system alters the macromolecular coil dimensions and total energy of elution of solvent molecules from the adsorption space of the porous adsorbents. Keeping these factors in view we can find the sign of the temperature adsorption coefficient. Diffusion coefficients increase in proportion to temperature, thus efficiency is usually enhanced, too, as peaks become more narrow. Prospects for optimization of the chromatographic process and, above all, the efficiency of separation of components of mixtures, include the effect of temperature on the adsorption of the components and their retention in the chromatographic column.

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Section: Introductionmentioning

confidence: 99%

Effect of temperature on adsorption and chromatography of polystyrene macromolecules

El’tekov¹

2018

sorpchrom

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“…Gradients of either solvent or temperature can be used as variant to control the adsorption. These separations were hyphenated with the separation with regard to molar mass, and experimental protocols for 2D-LC (HPLC × SEC) [75][76][77] have been applied for HT 2D-LC of a range of olefin copolymers [64][65][66][67][68][69][70][71][78][79][80][81][82]. Ginzburg et al [81] were the first to investigate BiHDPE using HT 2D-LC and examined the effect of temperature on the separation.…”

Section: Introductionmentioning

confidence: 99%

Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography

Prabhu

Brüll

Macko

et al. 2015

Journal of Chromatography A

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“…One of those, high‐temperature high performance liquid chromatography (HT‐HPLC) had shown superior capabilities for being able to analyze both amorphous and crystalline materials . The separation in HT‐HPLC depends mainly on the chemical composition of the polyolefin and in EP copolymers separation is according to the ethylene content of the sample . Several studies had been done on HT‐HPLC of metallocene EP copolymers but their focus was on the bulk samples .…”

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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Liquid chromatography at critical conditions of polyethylene

Cited by 31 publications

References 33 publications

Effect of temperature on adsorption and chromatography of polystyrene macromolecules

Effect of temperature on adsorption and chromatography of polystyrene macromolecules

Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography

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

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