An electron diffraction study of the crystalline structure of polyethylene terephthate by means of the Fourier synthesis

Tomashpol'skii, Yu. Ya.; Markova, G.S.

doi:10.1016/0032-3950(64)90311-9

Cited by 40 publications

(11 citation statements)

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“…The ratio of maximum positions of the first and second waves of intensity modulation on experimental dependences was approximately equal to 1.5 that corresponds to the ratio between the positions of maxima of the scattering intensity for the uniform cylinder [19]. Assuming that the position of the first minimum of intensity modulation observed at S 0 ≈ 0.024 nm -1 corresponds to the first zero of the Bessel function, based on the ratio 2 π r 0 S 0 ≈ 3.83 [20,21], we obtain the estimate of cylindrical pore radius r 0 ≈ 25.4 nm.…”

Section: Small-and Large-angle X-ray Scatteringmentioning

confidence: 98%

“…This means that the initial PET film and the membrane produced from this film contain identical crystalline phases and these phases were characterized by predominant orientation (texture). Judging by the reflex positions, the crystalline phase in the studied PET films and TMs had triclinic structure with the following parameters of unit cell: a ≈ 0.45 nm, b ≈ 0.60 nm, c ≈ 1.08 nm , α ≈ 100°, β ≈ 118°, and γ ≈ 111° [19].…”

Section: Small-and Large-angle X-ray Scatteringmentioning

confidence: 99%

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Peculiarities of the formation of track-etched membranes by the data of atomic force microscopy and X-ray scattering

et al. 2005

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FORMULATION OF A PROBLEMTrack-etched membranes (TMs) are polymer films with a system of ultrafiltration or microfiltration pores formed by the irradiation of initial (nonporous) films with the flux of high-energy particles and subsequent chemical treatment [1][2][3][4][5]. The TMs are usually produced on the base of the films of polyesters (polycarbonate and poly(ethylene terephthalate)) with the thickness of 5-25 µ m. The pores are formed due to the etching of tracks (the regions of the damaged initial structure of a polymer formed after the charged highenergy particles passed through polymer film) by the alkaline solutions. Accelerated heavy multi-charged ions or nuclear fission fragments are used more often as such particles.The sizes of TM pores usually ranged from 50 nm to 5 µ m; the number of pores per surface unit (pore surface density) varies from 10 6 to 10 9 cm -2 that corresponds to the values of bulk (or surface) porosity 1 from 5 to 10% (for commercial TMs, this value is usually larger, 10-20%) [5]. The TMs differ from ultra-and microfiltration membranes produced from polymer solutions or by the molding of finely dispersed powders mainly by a relatively small scatter of pore sizes (the deviation from the mean value does not usually exceed ± 5% ) [6]. As a rule, the pore shape in polymer TMs is close to cylindrical.The main requirement for TMs is a low scatter of shape and surface density of the pores at the stability of these parameters under the operating conditions, their prolonged storage, possible subsequent treatment (e.g., 1 The porosity was determined as the product of pore surface density by the cross-sectional area of a single pore.Abstract -Atomic force microscopy (AFM) is employed to obtain information on the main stages of the preparation of ultrafiltration track-etched membranes based on poly(ethylene terephthalate) (PET). The surface structure of initial commercial samples of PET films and the same films irradiated with various fluxes of accelerated heavy ions and subsequently treated with alkaline that results in the formation of pores owing to track etching is studied. It is shown that the order of the aforementioned stages of the formation of track-etched membranes with various porosities (from 0.02 to 6%) at a typical pore size of about 50 nm leads only to slight changes in surface structural parameters and does not fundamentally affect the polymer structure formed by spherulites with sizes that are comparable with the pore sizes. In this case, nearly the same content of the crystalline phase in the initial film and track-etched membrane are identified by large-angle X-ray scattering. The picture of X-ray scattering by track-etched membranes at small angles fully corresponds to the scattering on cylindrical pores with a diameter of about 50 nm. The analysis of the set of roughness profiles of the surfaces of initial films and track-etched membranes obtained by the AFM technique makes it possible to determine and introduce-in addition to standard parameters of the surface, the mean v...

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Section: Small-and Large-angle X-ray Scatteringmentioning

confidence: 98%

Section: Small-and Large-angle X-ray Scatteringmentioning

confidence: 99%

Peculiarities of the formation of track-etched membranes by the data of atomic force microscopy and X-ray scattering

et al. 2005

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“…They established that there are structural correlations between the conformation of the polyester and its model compounds. One of these, the polyethylene terephthalate, 2GT, studied by Astbury and Brown ( 6 ) , Daubeny, Bunn, and Brown (7), Tomashpol'skii and Markova (8), and Arnott and Wonacott (9) has a fiber repeat shorter by 0. 15 A than expected for the alltrans zigzag conformation.…”

Section: Introductionmentioning

confidence: 99%

“…-745(4) 103 l (2) 522 (4) s (1) 11711 (16) 1338 (6) 27371 (11) (7) 3652 (5) 779 (2) 2646(4) 229 C (8) 748 (6) -284 (2) 610 (4) 272 Mo radiation ( X = 0.71069 A) was small, no absorption correction was applied to either set of data.' The structures were solved using the multisolution program MULTAN.…”

Section: Introductionmentioning

confidence: 99%

The methylenic sequence conformation in a series of isoelectronic molecules

Deguire¹,

Brisse²

1988

Can. J. Chem.

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“…The departure from planarity was mostly locallzed in the glycol group. Tomashpol'skii and Markova (2) and Arnott and Wonacott (3) reinvestigated the structure of 2GT. Their structures are in general agreement with that proposed earlier by Daubeny et al…”

Section: Introductionmentioning

confidence: 99%

The effect of substitution on the conformation in para-substituted ethylene glycol dibenzoate molecules

Deguire¹,

Brisse²

1988

Can. J. Chem.

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The series of ethylene glycol di-para-X-benzoates, where X = Me, OMe, CN, and NO2, has been studied by infrared spectroscopy and solid state CP/MAS 13C nuclear magnetic resonance. The crystal structures were established for X = Me and OMe. Bond distances, bond angles, and torsion angles were compared to those of related molecules (X = H, Ph, Cl). It was found that the conformation of the CO—O—CH2—CH2—O—CO sequence is either trans-trans-trans or trans-gauche-trans. (trans = t, gauche = g). The CH2—CH2 bond distance ranging from 1.471(2) to 1.499(3) Å is always very short. The O—CH2—CH2 bond angle is around 105° for the ttt conformation and 107° for the tgt conformation. It was confirmed that the infrared frequencies for the CH2 bending, CH2 wagging, C–C stretching, and CH2 rocking modes are observed at 1470–1485, 1335–1340, 975–980, 845–855 cm−1 and at 1460, 1370–1375, 1040, 895–900 cm−1 for the ttt and tgt conformations respectively. The substitution effect on the nmr chemical shifts, both in solution and the solid state, can be rationalized in terms of induction and resonance contributions. On the basis of the ir and nmr spectra, it is proposed that for both the p-NO2 and p-CN substituted molecules, for which no crystal structure has been established, the conformation of the methylenic sequence is trans-trans-trans.

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An electron diffraction study of the crystalline structure of polyethylene terephthate by means of the Fourier synthesis

Cited by 40 publications

References 1 publication

Peculiarities of the formation of track-etched membranes by the data of atomic force microscopy and X-ray scattering

Peculiarities of the formation of track-etched membranes by the data of atomic force microscopy and X-ray scattering

The methylenic sequence conformation in a series of isoelectronic molecules

The effect of substitution on the conformation in para-substituted ethylene glycol dibenzoate molecules

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