Microstructure characterization of one high-speed extrusion coating polyethylene resin fractionated by solvent gradient fractionation

Li, Pei; Xue, Yanhu; Wu, Xiaoxue; Sun, Guangping; Ji, Xiangling; Bo, Shuhui

doi:10.1007/s10965-018-1480-z

Cited by 6 publications

(6 citation statements)

References 44 publications

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“…Polyethylene is the world’s most-produced synthetic polymer with 116 Mt per year (2015, corresponds to ∼29% of total synthetic polymer production) . It has excellent properties for a large variety of applications, such as coating, insulation, or wrapping. , Polyethylene consists of saturated hydrocarbons, and its structure can vary enormously . It is a mixture of many similar but differently long and dissimilarly branched chains.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Grimmer

Friederici

Streibel

et al. 2020

J. Am. Soc. Mass Spectrom.

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The rising demand for more and more specialized polyethylene represents a challenge for synthesis and analysis. The desired properties are dependent on the structure, but its elucidation is still intricate. For this purpose, we applied thermal analysis hyphenated to single photon ionization mass spectrometry (STA-SPI-MS). The melting and pyrolysis behavior of different types of polyethylene were tracked by DSC and mass loss. Crystallinity and melting point give hints about the branching but are also influenced by the molecular weight distribution. The evolving gas analysis patterns obtained by SPI-MS however, contain specific molecular information about the samples. Shifts in the summed spectra, which can be clearly observed with our technique, result from differently favored degradation reactions due to the respective structure. Pyrolysis gas chromatography mass spectrometry (Py-GC-EI-MS) was used to support the assignment of pyrolysis products. Principal component analysis was successfully applied to reduce the complexity of data and find suitable markers. The obtained grouping is based on the molecular fingerprint of the samples and is strongly influenced by short-chain branching. Short and medium alkenes and dienes have the strongest impact on the first four principal components. Thus, two marker ratios could be defined, which also give a comprehensible and robust grouping. Butene and pentene were the most abundant signals in our set of samples. With STA-PI-MS, a broad range of pyrolysis products can be measured at the same time, possibly extending the range for quantifiable short-chain branches to more than six carbon atoms for PE. Unfortunately, no clear trend between long-chain branching and any grouping was observed. The quite universal and soft single photon ionization enables access to many different compound classes and hence other polymers can be studied.

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Section: Introductionmentioning

confidence: 99%

“…1 It has excellent properties for a large variety of applications, such as coating, insulation, or wrapping. 2,3 Polyethylene consists of saturated hydrocarbons, and its structure can vary enormously. 4 It is a mixture of many similar but differently long and dissimilarly branched chains.…”

Section: ■ Introductionmentioning

confidence: 99%

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Grimmer

Friederici

Streibel

et al. 2020

J. Am. Soc. Mass Spectrom.

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“…13 C NMR spectroscopy, when performed correctly, provides an intrinsically quantitative method for LCB quantification, and it has been widely used to measure LCB level in SLEP. − 13 C NMR spectroscopy has also been used extensively to measure LCB content in LDPE by quantifying the resonance from the CH 2 group located at the third carbon from the chain end (CE 3 ) resonating at approximately δ 32.1–32.3 ppm (see Scheme ; the drawing is based on previous NMR reports , ). Prior papers report values for LCB content in LDPE where any contribution from C 6 branches to longer branches is included in the LCB value because it was not possible to resolve the C 6 resonance from the resonances corresponding to longer chains. ,,,− In addition, it has been reported previously that C 6 branches are not present in LDPE . Recently, we reported a new 13 C NMR method in which halogenated naphthalenes are used as NMR solvents in experiments to detect and quantify LCB content in SLEP.…”

Section: Introductionmentioning

confidence: 99%

“…37−42 This approach can also be used to obtain information about CH and CH 3 in the material of interest. It is likely to work for other nuclei such as 15 N and 29 Si. The key advantages are (1) it is applicable to samples that have carbons without attached protons (although these carbons' signals cannot be enhanced), such as LDPE, poly(ethylene-co-acrylic acid), and EPDM; (2) it should also work for functional groups which have drastically different C−H J coupling constants, such as vinyl groups; and (3) the tolerance of error of T (CNST 11 in Bruker pulse sequence) in RINEPT and the error of pulse width in DEPT are much higher, as shown in Figure 7.…”

Section: ■ Introductionmentioning

confidence: 99%

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Long Chain Branching Detection and Quantification in LDPE with Special Solvents, Polarization Transfer Techniques, and Inverse Gated ¹³C NMR Spectroscopy

et al. 2018

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Recent global demand of polyethylene was 187 billion pounds with 23% being low density polyethylene (LDPE). LDPE is used in a variety of applications including liners, consumer bags, heavy duty sacks, caps, closures, toys, lamination, and agricultural films. A key feature of LDPE is the presence of long chain branching (LCB) which has a significant impact on physical and rheological properties, including melt strength. Previously it was reported that there are no C6 branches in LDPE, and therefore the common practice has been to use the resonance around 32.2 ppm as a measure of LCB content. Herein, the existence of C6 branches in LDPE is reported for the first time, enabled by the use of 1-chloronaphthalene as the NMR solvent. It is shown that the C6 branches have a contribution to the resonance around 32.2 ppm. This finding suggests that C6 branches should be measured in LDPE samples and be excluded from LCB quantification because they do not affect LDPE rheological properties as LCB does. The data obtained strongly suggest that C7 branches are present in much lower concentrations in the LDPE samples studied. The quantification of these resonances traditionally requires long acquisition time, even with the use of a cryoprobe. In this work, different polarization transfer techniques, refocused insensitive nuclei enhanced by polarization transfer (RINEPT), and distortionless enhancement by polarization transfer (DEPT) were compared in terms of their ability to enhance CH2 sensitivity, thus leading to a greater ability to observe the CH2 resonances belonging to the C6 branches. It was found that RINEPT with hard 180° 13C pulses is most suitable for this purpose. A much faster method is proposed for measuring LCB in LDPE that employs a combination of a conventional quantitative 13C NMR technique and a polarization transfer technique.

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Chain structure comparison of two low density polyethylene resins fractionated by temperature rising elution fractionation and thermal fractionation

Xue

Liu

et al. 2019

J Polym Res

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Microstructure characterization of one high-speed extrusion coating polyethylene resin fractionated by solvent gradient fractionation

Cited by 6 publications

References 44 publications

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Long Chain Branching Detection and Quantification in LDPE with Special Solvents, Polarization Transfer Techniques, and Inverse Gated ¹³C NMR Spectroscopy

Chain structure comparison of two low density polyethylene resins fractionated by temperature rising elution fractionation and thermal fractionation

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Microstructure characterization of one high-speed extrusion coating polyethylene resin fractionated by solvent gradient fractionation

Cited by 6 publications

References 44 publications

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

Long Chain Branching Detection and Quantification in LDPE with Special Solvents, Polarization Transfer Techniques, and Inverse Gated 13C NMR Spectroscopy

Chain structure comparison of two low density polyethylene resins fractionated by temperature rising elution fractionation and thermal fractionation

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Long Chain Branching Detection and Quantification in LDPE with Special Solvents, Polarization Transfer Techniques, and Inverse Gated ¹³C NMR Spectroscopy