Novel in situ NMR Measurement System for Evaluating Molecular Mobility during Drawing from Highly Entangled Polyethylene Melts

Kakiage, Masaki; Uehara, Hiroki; Yamanobe, Takeshi

doi:10.1002/marc.200800316

Cited by 35 publications

(21 citation statements)

References 38 publications

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“…There are two types of entanglements: “shallow” entanglement, which is easily disentangled during drawing, and “deep” entanglement, which persists even after melt‐drawing 2. These types are distinguishable based on the relaxation time of molecular chains 11. Rastogi et al12, 13 claim that different entanglements located heterogeneously or homogeneously are formed during rapid or gradual heating of UHMW‐PE materials in the melt.…”

Section: Introductionmentioning

confidence: 99%

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

Uehara

Tamura

Kakiage

et al. 2012

Adv Funct Materials

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Crystalline homopolymers, including polyethylene (PE), which has the simplest architecture, form a nanometer‐sized combination of crystalline and amorphous components, but their arrangement control, similar to self‐assembled phase‐separation of block‐copolymers, is usually difficult. However, molecular entanglements trapped between crystalline and amorphous components of homopolymers coincide with the segmental linking points on the interfaces of the microphase separation for block copolymers. Nanowrinkled PE membranes are prepared with a network of 30 nm‐thick homogeneous lamellae using a novel entanglement control technique composed of biaxial melt‐drawing and melt‐shrinking procedures, which are limited for highly entangled ultrahigh molecular weight materials. Such a network arrangement of nanowrinkling lamellae spreading on membrane surface and also across the membrane thickness improves the mechanical properties of both tensile strength and tearing strength. Subsequent cold‐drawing causes delamination of the lamellar interfaces, leading to the resultant nanoporous morphology composed of passing‐through channels that are several tens of nanometers in diameter, without any solvent processing.

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Section: Introductionmentioning

confidence: 99%

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

Uehara

Tamura

Kakiage

et al. 2012

Adv Funct Materials

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“…In contrast, for drawing at 130 °C in the semimolten state, the applied stress is transmitted via UHMW-PE chains having long relaxation times even though HDPE chains are disentangled, since UHMW-PE can be drawn even in the molten state. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The UHMW-PE chains are highly oriented and form oriented crystals; then, highly stacked lamellar crystals with higher chain orientation are formed. The increase in UHMW-PE content induces effective stress transfer with high chain orientation, resulting in the development of the oriented crystalline structure and high tensile strength.…”

Section: Resultsmentioning

confidence: 99%

“…UHMW-PE can be drawn even in the molten state since chain entanglements effectively transmit the drawing stress. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Recently, we have successfully prepared highperformance UHMW-PE fibers by melt-processing, i.e., a combination of melt-spinning and melt-drawing. [17] the PE powder was mixed in an acetone solution of two antioxidants, 0.5 wt% (based on polymer) of both octadecyl 3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate (ADK STAB AO-50, ADEKA Corporation, Japan) and 2,2′-methylenebis(4,6-ditert-butylphenyl) 2-ethylhexyl phosphite (ADK STAB HP-10, ADEKA Corporation, Japan), and dried at room temperature (RT).…”

Section: Introductionmentioning

confidence: 99%

High‐Strength and High‐Toughness Melt‐Spun Polyethylene Fibers Derived from Composite Structure Formation

Kakiage

Takei

2020

Macro Materials & Eng

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Low-molecular-weight PE such a highdensity PE (HDPE) is often blended with UHMW-PE to improve its melt processability. [18-28] For instance, high-strength UHMW-PE/HDPE blended fibers were prepared by melt-spinning. [23,28] Interestingly, the blending of UHMW-PE induces the development of mechanical properties originating from the composite structure formation for melt-proces sing. [19,21,24,25,27,29] This is because the difference in stress transmissibility between HDPE chains and UHMW-PE chains in the molten state based on the difference in relaxation time. [13] UHMW-PE chains transfer the applied stress via entanglements owing to its long relaxation time [30] and form highly oriented crystals (extended-chain crystals) even in melt-proces sing, [3-6,11,12,16,17] whereas HDPE chains are disentangled and provide lamellar crystals (folded-chain crystals). In this study, we attempted to prepare high-performance PE fibers by melt-spinning and subsequent drawing in the semimolten state of HDPE combined with UHMW-PE by introducing a structural composite effect based on the difference in relaxation time. The as-spun fiber prepared by melt-spinning was drawn just below the melting temperature (semimolten state) to induce highly oriented chains derived from UHMW-PE. The formation of highly oriented crystals derived from UHMW-PE contributes to high tensile strength, but energy absorption ability is poor. On the other hand, the formation of the lamellar structure derived from HDPE induces energy absorption, i.e., high toughness, derived from the deformation of lamellar crystals. Hence, the composite crystalline structure having different structural functions can be formed by the drawing of a HDPE/ UHMW-PE blended fiber in the semimolten state, resulting in a PE fiber with both high tensile strength and high toughness. 2. Experimental Section 2.1. Materials HDPE reactor powder having a weight-average MW of 1.0 × 10 5 (J-REX, Japan Polyolefins Co., Ltd., Japan) and UHMW-PE reactor powder having a viscosity-average MW of 1.15 × 10 6 (HI-ZEX MILLION 145M, Mitsui Chemicals, Inc., Japan) were used. UHMW-PE powder was blended with HDPE powder at the blend ratio of 0-30 wt% (Table 1). Before melt-spinning, High-strength and high-toughness polyethylene (PE) fibers are prepared by the melt-spinning and subsequent drawing in the semimolten state of highdensity PE (HDPE) combined with ultrahigh-molecular-weight PE (UHMW-PE). As-spun fibers are prepared by the melt-spinning of HDPE/UHMW-PE blended powder with 0-30 wt% UHMW-PE. The as-spun fiber is drawn at 100 (solid state) and 130 °C (semimolten state). Well-arranged stacked lamellae with highly oriented crystals are formed based on the difference in relaxation time for the drawn fiber with 30 wt% UHMW-PE prepared at 130 °C in the semimolten state. This composite structure results in a PE fiber with high tensile strength (1.11 GPa) and high toughness (297 MJ m −3).

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“…In-situ detection of the curing state requires the enhancement of sensitivity such as the isotopical labeling. 1 H pulse NMR spectroscopy of solid polymers gives spectra with high sensitivity and measuring time as short as orders of second if the sample is sufficient enough [6,7]. From 1 H pulse NMR, relaxation times such as spin-lattice relaxation time (T 1 ), spin-spin 0022-2860/$ -see front matter Ó 2010 Elsevier B.V. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Structure and curing mechanism of high-ortho and random novolac resins as studied by NMR

Nomoto

Fujikawa

Kōmoto

et al. 2010

Journal of Molecular Structure

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Novel in situ NMR Measurement System for Evaluating Molecular Mobility during Drawing from Highly Entangled Polyethylene Melts

Cited by 35 publications

References 38 publications

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

High‐Strength and High‐Toughness Melt‐Spun Polyethylene Fibers Derived from Composite Structure Formation

Structure and curing mechanism of high-ortho and random novolac resins as studied by NMR

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