Crystal structure of isotactic poly(4‐methyl‐1‐pentene)

Kusanagi, Hiroshi; Takase, Minoru; Chatani, Yôzô; Tadokoro, Hiroyuki

doi:10.1002/pol.1978.180160112

Cited by 105 publications

(130 citation statements)

References 22 publications

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“…This result suggests the width of the cavity in PMP crystal lies between 4.1 Å that is the diameter of CO 2 and CH 4 and 5.2 Å that is that of C 3 H 8 . This estimation is fundamentally consistent with the results obtained from X-Ray analysis by Kusanagi et al and gas transport measurements by Paul et al 8,10,11 Xe Sorption and 129 Xe NMR Measurements Figure 3 shows Xe sorption isotherms of PMP membranes at 25 • C. It appears that sorption amount of Xe increases in proportion to applied pressure. These isotherms can be described by the Henry's mode sorp- …”

Section: Xe Nmr Measurementssupporting

confidence: 81%

“…It is one of the significant properties of PMP that the density of crystal region is lower than that of amorphous region. [5][6][7] Kusanagi et al have investigated the crystal structure of PMP 8 termed as "Form I", 9 which is characterized by molecular chains in 7/2 helical conformation packed in a tetragonal unit cell, and concluded that the lower density of crystal region is attributed to a coarse packing of the chains, as a result, the cylindrical cavity with a diameter of about 4 Å is formed in the crystal. This fact means that transport phenomena of gas and vapor molecules occur in not only amorphous but also crystal regions.…”

mentioning

confidence: 99%

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Characterization of the Cavity in Poly(4-methyl-1-pentene) Crystal by Gas Permeation and 129Xe NMR Measurements

Suzuki

Tanaka

Nakajima

et al. 2002

Polym J

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ABSTRACT:Characteristic cavity in a crystal part of poly(4-methyl-1-pentene) (PMP) has been investigated by gas permeation and 129 Xe NMR measurements for PMP membranes with various crystallinities. For the cavity, permeability coefficients of He, N 2 , O 2 , CH 4 , and CO 2 have shown finite values, whereas those of C 3 H 8 and tert-C 4 H 10 have shown zero. From the analysis of 129 Xe NMR chemical shifts of 129 Xe sorbed in PMP membranes, it has been able to evaluate the size of the cavity in PMP crystal as about 4.5 Å. These findings have indicated that gas molecules less than about 4.5 Å can permeate the cavity in PMP crystal.

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Section: Xe Nmr Measurementssupporting

confidence: 81%

mentioning

confidence: 99%

Characterization of the Cavity in Poly(4-methyl-1-pentene) Crystal by Gas Permeation and 129Xe NMR Measurements

Suzuki

Tanaka

Nakajima

et al. 2002

Polym J

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“…32 Its crystal structure consists of four 7/2 helices packed in a tetragonal unit cell of dimensions a = 18.70 Å and c = 13.68 Å. This structure was investigated at atomic level by refining the X-ray data with a constrained least-squares (CLS) method.…”

Section: Nvt Simulations Of Crystalline Poly(4-methyl-1-pentene)mentioning

confidence: 99%

“…The starting geometry for the MCDP simulations was taken from Ref. 32. Accordingly, four helices were packed in a tetragonal box at the positions indicated in Figure 5.…”

Section: Nvt Simulations Of Crystalline Poly(4-methyl-1-pentene)mentioning

confidence: 99%

MCDP: an advanced tool to simulate comb-like polymers

et al. 2000

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A strategy to study polymeric systems with ordered structures, and in particular comb-like polymers, is presented. These are dense systems for which atomistic simulations with conventional methods are difficult or even impracticable. The strategy, which has been incorporated into a computer program named MCDP, is based on a Configuration Bias Monte Carlo algorithm and a method to investigate the structure of crystalline polymers using force-field calculations. To obtain a maximum efficiency, the MCDP computer program has been optimized and parallelized. The ability of MCDP to investigate ordered polymers have been tested by simulating two complex systems: (1) the crystal structure of poly(4-methyl-1-pentene), and (2) the biphasic structure of poly(α-octyl-β-L-aspartate), a comb-like polyamide derived from β-amino acids. The results obtained from MCDP simulations demonstrates the efficiency and reliability of this method to study both the NVT and NPT behavior of ordered dense polymers.

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“…Daubeny, 0021-8898/87/030246-10501.50 © 1987 International Union of Crystallography Bunn & Brown, 1954;Holmes, Bunn & Smith, 1955) and was still being used a few years ago (e.g. Kusanagi, Takase, Chatani & Tadokoro, 1978). However, singlescan microdensitometers are now widely used, with arc-correction factors being applied for the azimuthal spread of reflections and its change with diffraction angle (e.g.…”

Section: Introductionmentioning

confidence: 99%

A computer-based method of measuring the integrated intensities of the reflections on the X-ray diffraction photograph of an oriented crystalline polymer

Hall¹,

Neisser²,

Elder³

1987

J Appl Cryst

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The method is designed to be used with a batchprocessing computer system and will determine the integrated intensities of the spots on an X-ray diffraction photograph of an oriented fibre of a partially crystalline synthetic polymer. It is necessary to assume that the spot boundary is elliptical, that the intensity distribution along any line through the centre of this ellipse is Gaussian, and that the background intensity variation is linear over the region of a spot; these are justified experimentally, although, in the radial direction, the choice of a Gaussian intensity distribution is probably theoretically unsound. The computational procedures correct for minor differences between users in the choice of input parameters and reject bad choices. The method was applied to determine the intensities of the 30 visible spots in the diffraction photograph of oriented poly(trimethylene terephthalate) which were used in a subsequent structure refinement. Successful integrations were obtained for 22 spots, the failures being (1) pairs of similar intensity just resolved by eye, (2) better resolved pairs of which one member is much stronger than the other, or (3) very weak. Statistical tests indicated very much better internal consistency of data than is usually obtained with these materials, and enabled a rational weighting scheme to be used in the structure refinement. The R factor of 7-9% obtained is unusually low, indicating much improved accuracy over earlier methods.

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Crystal structure of isotactic poly(4‐methyl‐1‐pentene)

Cited by 105 publications

References 22 publications

Characterization of the Cavity in Poly(4-methyl-1-pentene) Crystal by Gas Permeation and 129Xe NMR Measurements

Characterization of the Cavity in Poly(4-methyl-1-pentene) Crystal by Gas Permeation and 129Xe NMR Measurements

MCDP: an advanced tool to simulate comb-like polymers

A computer-based method of measuring the integrated intensities of the reflections on the X-ray diffraction photograph of an oriented crystalline polymer

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