Monoclinic polyethylene revisited

Russell, K. E.; Hunter, Brian K.; Heyding, R. D.

doi:10.1016/s0032-3861(96)00643-x

Cited by 118 publications

(126 citation statements)

References 22 publications

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“…Other reported crystallographic forms of PE include monoclinic, triclinic, and hexagonal PE structures. [ 15,35 ] The d-spacings of these literature reported structures still do not match with the two new ones detected in the present case. We can therefore exclude the already known and reported crystal forms of PE.…”

Section: Resultscontrasting

confidence: 93%

“…[10][11][12][13][14] Moreover, depending on the thermal and mechanical history, PE can adopt various ordered chain packings, namely orthorhombic, monoclinic, and triclinic. [15][16][17][18][19][20][21] In these different stacking arrangements, the polymer chains still retain an all-trans confi guration. [ 12 ] The introduction of nanodiamond particles (NDs) in silane-crosslinked polyethylene is found to lead to a notable and systematic deformation of the polymer unit cell.…”

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confidence: 99%

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Modified Crystalline Structure of Silane-Crosslinked Polyethylene in the Proximity of Nanodiamonds

Roumeli

Brus

Policianova

et al. 2016

Macromol. Mater. Eng.

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The introduction of nanodiamond particles (NDs) in silane‐crosslinked polyethylene is found to lead to a notable and systematic deformation of the polymer unit cell. X‐ray diffraction evidence of the existence of a modified crystalline structure in the bulk of the polymer due to the presence of NDs is reported here for the first time. The covalent bonding between NDs and the surrounding macromolecular chains may support that the excessive local stress field ultimately distorts the polymer conformation, yielding a new distorted but still crystalline interface. Supporting data from solid‐state NMR experiments confirm the existence of a modified crystalline interface of about 1–2 nm in all the nanocomposite materials.

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Section: Resultscontrasting

confidence: 93%

mentioning

confidence: 99%

Modified Crystalline Structure of Silane-Crosslinked Polyethylene in the Proximity of Nanodiamonds

Roumeli

Brus

Policianova

et al. 2016

Macromol. Mater. Eng.

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“…6 shows the main peaks of the XRD pattern of the polymer obtained at 30 bar. The peaks (1 1 0) and (2 0 0) at 21.5 • and 23.8 • , respectively correspond to the orthorhombic reflections of polyethylene, while the peak (0 0 1) at 19.4 • corresponds to a monoclinic phase of polyethylene [37,38]. The last peak appears infrequently in linear polyethylenes [37].…”

Section: Solid Products Obtained At Higher Ethylene Pressuresmentioning

confidence: 99%

“…X-ray diffraction is also used to measure the extent of crystallinity present in the polymers [37]. It is important to know that, the crystallinity values obtained with XRD differ slightly from values measured with DSC because the last method determines certain conformational changes during the measurement induced by the sample heating [37,38].…”

Section: Solid Products Obtained At Higher Ethylene Pressuresmentioning

confidence: 99%

“…It is important to know that, the crystallinity values obtained with XRD differ slightly from values measured with DSC because the last method determines certain conformational changes during the measurement induced by the sample heating [37,38]. In Table 6, the crystallinity degree of the polymers analysed with DSC and XRD is compared.…”

Section: Solid Products Obtained At Higher Ethylene Pressuresmentioning

confidence: 99%

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Turning a Cr-based heterogeneous ethylene polymerisation catalyst into a selective ethylene trimerisation catalyst

Nenu

Bodart

Weckhuysen

2007

Journal of Molecular Catalysis A: Chemical

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A Phillips Cr/SiO 2 polymerisation catalyst was converted into an ethylene trimerisation catalyst after assembling new active sites on the silica surface in the presence of TAC (1,3,5-triphenylhexahydro 1,3,5-triazacyclohexane) as ligand and CH 2 Cl 2 as solvent. The reaction conditions play a role in tuning the catalytic activity of this system. It is a true trimerisation catalyst at low ethylene pressures, while, at high pressures, the polymerisation activity becomes dominant. Moreover, at high ethylene pressures, polyethylene characterised by a high crystallinity degree is obtained. Instead, a highly branched heavy oligomer of ethylene characterised by a very narrow molecular weight distribution is obtained at 1 bar. 1-Hexene, formed as the main product in the ethylene trimerisation reaction at low pressures, is partially incorporated into this growing oligomer making redundant the use of a second comonomer feedstock and an expensive catalyst.

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Biodegradable High‐Density Polyethylene‐like Material

et al. 2022

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We report a novel polyester material generated from readily available biobased 1,18‐octadecanedicarboxylic acid and ethylene glycol possesses a polyethylene‐like solid‐state structure and also tensile properties similar to high density polyethylene (HDPE). Despite its crystallinity, high melting point (Tm=96 °C) and hydrophobic nature, polyester‐2,18 is subject to rapid and complete hydrolytic degradation in in vitro assays with isolated naturally occurring enzymes. Under industrial composting conditions (ISO standard 14855‐1) the material is biodegraded with mineralization above 95 % within two months. Reference studies with polyester‐18,18 (Tm=99 °C) reveal a strong impact of the nature of the diol repeating unit on degradation rates, possibly related to the density of ester groups in the amorphous phase. Depolymerization by methanolysis indicates suitability for closed‐loop recycling.

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Monoclinic polyethylene revisited

Cited by 118 publications

References 22 publications

Modified Crystalline Structure of Silane-Crosslinked Polyethylene in the Proximity of Nanodiamonds

Modified Crystalline Structure of Silane-Crosslinked Polyethylene in the Proximity of Nanodiamonds

Turning a Cr-based heterogeneous ethylene polymerisation catalyst into a selective ethylene trimerisation catalyst

Biodegradable High‐Density Polyethylene‐like Material

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