Discovery in nylon-8 chain-folded lamellar crystals of new structure??-structure?with progressive intersheet shear along the chain axis

Jones, Nathan; Sikorski, Pawel; Atkins, E. D. T.; Hill, M. J.

doi:10.1002/1099-0488(20001215)38:24<3302::aid-polb120>3.0.co;2-p

Cited by 29 publications

(64 citation statements)

References 11 publications

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“…Sometimes, the Brill transition of nylons is defined on the basis of such an X-ray diffraction observation that the 100 and 010 (and 110) reflections are merged into one above the Brill transition temperature [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], corresponding to the perfect change of the chain packing mode from triclinic to pseudo-hexagonal type. If these two reflections do not merge into one even above the melting temperature, people say that the nylon sample does not have a Brill transition point.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it might be more suitable to define the Brill transition phenomenon, not in terms of the behavior of the X-ray equatorial reflections, rather in terms of the conformational disordering with the intermolecular hydrogen bonds kept unbroken even above the transition temperature region. So far, many people including us have investigated the structural changes in the Brill transition mainly on the basis of the X-ray diffraction [2][3][4][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] and infrared spectral data [1][2][3][4]29,30] and also by the molecular dynamics (MD) calculation [5,31]. In most of the papers, however, the X-ray reflections used in the discussion are almost limited to the main 100 and 010/110 equatorial reflections only.…”

Section: Introductionmentioning

confidence: 99%

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Conformational disorder in the Brill transition of uniaxially-oriented nylon 10/10 sample investigated through the temperature-dependent measurement of X-ray fiber diagram

Tashiro

Yoshioka

2004

Polymer

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conformational disorder in the Brill transition of uniaxially-oriented nylon 10/10 sample investigated through the temperature-dependent measurement of X-ray fiber diagram

Tashiro

Yoshioka

2004

Polymer

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“…Many papers had been published to clarify the structural changes in this transition, but the details have not yet been revealed. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] As one of the most useful methods to solve these problems we may utilize the various kinds of lowmolecular-weight model compounds having similar chemical structures with nylons. In a lucky case we might be able to prepare the single crystals, which would give us precise information about the chain conformation as well as the chain packing mode.…”

Section: Introductionmentioning

confidence: 99%

Structural Changes in Phase Transitions of Nylon Model Compounds. 1. Transition Behavior of Model Compounds of R-NHCO-R‘ Type

Yoshioka

Tashiro

2003

J. Phys. Chem. B

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To clarify the essential features of Brill transition of aliphatic nylons, structural changes have been investigated by X-ray diffraction and infrared spectroscopic methods for the compounds CH 3 (CH 2 ) 10 NHCO(CH 2 ) 9 CH 3 (designated as N11) and CH 3 (CH 2 ) 9 NHCO(CH 2 ) 8 CH 3 (N10) which were assumed to be the simplest models of nylons 11/11 and 10/10, respectively. Depending on the preparation conditions, N11 crystallized to the R and γ forms and N10 to the R form at room temperature. Infrared and X-ray diffraction data clarified that the R form took essentially the same chain packing structure as that of the R form of parent nylons, in which the all-trans methylene segments were packed in a triclinic subcell and the amide groups were connected by intermolecular hydrogen bonds to form a sheet structure and these sheets were stacked by a weak van der Waals force. In the DSC thermograms, the R form of N10 and N11 showed two main endothermic peaks in the Brill transition (ca. 50°C) and melting regions. The temperature region was divided into three (I, II, and III). In region I below 50°C, the crystal was of the R type. In region III (above 58°C for N10 and above 65°C for N11), the crystal transferred to the high-temperature γ form (γ h ), in which the molecular chains had disordered conformation, as speculated from the change in methylene progression bands and the broad amide bands, and these chains were packed in a pseudohexagonal mode. During the transition from region I to III, another phase was observed to appear discontinuously in region II. This intermediate phase showed the infrared spectra composed of the characteristic patterns of the R and γ h forms but the X-ray diffraction pattern was quite unique and different from those of the latter two forms, indicating that the molecules with a hybrid conformation between the R and γ h forms were packed in a unique crystal lattice. In case of the γ form of N11 compound, the molecular chains took the conformation built by skewed amide groups and partially disordered trans methylene segments even at room temperature. The crystal transferred apparently continuously to the γ h form above 70°C.

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“…Nylon 66 is a semicrystalline polyamide that crystallizes in two known triclinic crystal structures named α and β . At room temperature both structures can be found in chain‐folded lamellae, usually composed of hydrogen‐bonded sheets stacked together via Van der Waals interactions 2. The α structure is the most probable one when the polymer crystallizes from the melt.…”

Section: Introductionmentioning

confidence: 99%

Transcrystallinity in Surface Modified Aramid Fiber Reinforced Nylon 66 Composites

Feldman¹,

González²,

Marom³

2003

Macro Materials & Eng

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Aramid (kevlar‐49) fibers were surface treated by two different methods to induce roughness and then used to produce unidirectional nylon 66 based composites. The transcrystallinity generated around the treated fibers was characterized by SEM and polarized light microscopy and compared with the regular transcrystalline layers produced by pristine aramid under the same processing conditions. The treated fibers generated a double transcrystalline layer, the inner layer being thinner and more compact than the regular nylon 66 transcrystallinity. In addition, mechanical testing of the composites showed the longitudinal Young's modulus of the treated fiber composites to be significantly higher than the control in a wide range of fiber volume fractions.Polarized light microscopy picture of double transcrystallinity in Br/NH3 treated aramid fiber reinforced nylon 66.magnified imagePolarized light microscopy picture of double transcrystallinity in Br/NH3 treated aramid fiber reinforced nylon 66.

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Discovery in nylon-8 chain-folded lamellar crystals of new structure??-structure?with progressive intersheet shear along the chain axis

Cited by 29 publications

References 11 publications

Conformational disorder in the Brill transition of uniaxially-oriented nylon 10/10 sample investigated through the temperature-dependent measurement of X-ray fiber diagram

Conformational disorder in the Brill transition of uniaxially-oriented nylon 10/10 sample investigated through the temperature-dependent measurement of X-ray fiber diagram

Structural Changes in Phase Transitions of Nylon Model Compounds. 1. Transition Behavior of Model Compounds of R-NHCO-R‘ Type

Transcrystallinity in Surface Modified Aramid Fiber Reinforced Nylon 66 Composites

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