Comparison of analytical and preparative TREF analysis: A mathematical approach to correcting analytical TREF data

Pigeon, Michael; Rudin, Alfred

doi:10.1002/app.1993.070470412

Cited by 8 publications

(1 citation statement)

References 8 publications

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“…However, as all three techniques require crystallization, they can only be applied to samples that exhibit a sufficient degree of crystallinity. TREF and CRYSTAF have been used to study the composition of blends containing various polyolefins,8, 9 the microstructure of polypropylene (PP),10–13 and the composition distribution of copolymers of either ethylene14–18 or propylene19 with 1‐olefins. The chemical heterogeneity, that is, the relationship between the MMD and CCD can be evaluated by coupling TREF with SEC (TREF × SEC).…”

Section: Introductionmentioning

confidence: 99%

Multidimensional high‐temperature liquid chromatography: A new technique to characterize the chemical heterogeneity of Ziegler‐Natta‐based bimodal HDPE

Ginzburg

Macko

Dolle

et al. 2012

J of Applied Polymer Sci

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High temperature two-dimensional liquid chromatography (HT 2D-LC) was recently introduced as a new technique to analyze the heterogeneities with regard to composition and molar mass present in model blends of polyolefins and various olefin copolymers. The method uses graphite as stationary phase and solvent gradients of 1-decanol 1,2,4-trichlorobenzene as mobile phase for the compositional separation. With the aim to maximize the chromatographic resolution, the influence of the separation's temperature in the first dimension was evaluated: approaching the -temperature of polyethylene (PE) in 1-decanol selectively enhances the retention of higher molar mass PE standards while that of the lower molar mass ones is hardly affected. A bimodal ethylene/1-butene copolymer and its temperature rising elution fraction (TREF) fractions were separated by HT 2D-LC. For the first time, both axes of the contour plot were calibrated with regard to chemical composition and molar mass, respectively. Prefractionation of the bulk sample by TREF enhances the detectability of separated components of the 2D separation. The influence of the separation temperature, that is, working around the theta-temperature of PE in 1-decanol, can be used to enhance the chromatographic resolution of the 2D chromatography

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Section: Introductionmentioning

confidence: 99%

Multidimensional high‐temperature liquid chromatography: A new technique to characterize the chemical heterogeneity of Ziegler‐Natta‐based bimodal HDPE

Ginzburg

Macko

Dolle

et al. 2012

J of Applied Polymer Sci

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Branching measurement by analytical TREF: A fully quantitative technique

Pigeon

Rudin

1994

J of Applied Polymer Sci

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SYNOPSISConversion of analytical TREF data to accurate branching distributions of polyethylene requires a calibration of branching frequency as a function of elution temperature. It has been found that the elution temperature of a semicrystalline polymer such as polyethylene depends on molecular weight, branch content, branch length, and branch clustering. It stands to reason that every polymer will have its own unique relation of branch frequency and elution temperature. Ideally, the polymer would be fractionated by a preparative TREF technique and the fractions analyzed by NMR or IR to determine branch frequency with respect to elution temperature. This method is tedious and time-consuming. An alternative method is described here to determine the relation between branch frequency and TREF elution temperature and to generate a calibration from analytical TREF data only. A twodetector system is used to simultaneously measure both concentration and branching frequency as a function of elution temperature. Each polymer is analyzed using analytical TREF data alone, eliminating the need for preparative TREF fractionation and NMR analysis of the fractions.

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Elongational flow properties of low‐density polyethylene and linear low‐density polyethylene from nonisothermal melt spinning experiments

Bailey

Cook

Pronovost

et al. 1994

Polymer Engineering & Sci

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Low‐density polyethylene (LDPE) and also linear low‐density polyethylene (LLDPE) resins can be characterized by the degree of strain hardening and down‐gaging during elongation. A new method for the determination of the apparent elongational flow characteristics is presented. In a small scale apparatus, a molten monofilament is stretched under nonisothermal conditions similar to those found in tubular film extrusion. Measurement of resistance to elongational flow and apparent elongational strain rates permit the comparison of the process‐ability of different resins under specified conditions. The effect of melt temperature and extension ratio are examined. The importance of the molecular structure of both LDPE and LLDPE resins on these properties is also outlined.

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Comparison of analytical and preparative TREF analysis: A mathematical approach to correcting analytical TREF data

Cited by 8 publications

References 8 publications

Multidimensional high‐temperature liquid chromatography: A new technique to characterize the chemical heterogeneity of Ziegler‐Natta‐based bimodal HDPE

Multidimensional high‐temperature liquid chromatography: A new technique to characterize the chemical heterogeneity of Ziegler‐Natta‐based bimodal HDPE

Branching measurement by analytical TREF: A fully quantitative technique

Elongational flow properties of low‐density polyethylene and linear low‐density polyethylene from nonisothermal melt spinning experiments

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