Crystallographic studies of nylon 4. I. Determination of the crystal structure of the α polymorph of nylon 4

Fredericks, Robert J.; Doyne, Thomas H.; Sprague, Robert S.

doi:10.1002/pol.1966.160040606

Cited by 33 publications

(18 citation statements)

References 8 publications

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“…For PA‐3 the cross‐section has been obtained from an X‐ray structure measured by Masamoto et al 12. For PA‐4 the cross‐section was calculated from a structure measured by Fredericks et al 13. For PA‐6 the experiment by Malta et al 14 has been used.…”

Section: Resultsmentioning

confidence: 99%

Ab initio calculation of the Young's modulus of α‐polyamides

Peeters¹,

Alsenoy²,

Bartha³

et al. 2002

Int J of Quantum Chemistry

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ABSTRACT:In earlier works the supermolecule model has been applied to the calculation of the Young's modulus of crystalline polyethylene and polyamide-6. In the supermolecule model a crystalline polymer is represented as a single finite chain divided into a head, body, and tail part. The body contains a number of monomer units and is representative for a polymer chain. In this article, this model has been used to study the geometric properties and the elastic moduli of the ␣ form of other polyamides: polyamide-2 (or polyglycine), polyamide-3, polyamide-4, polyamide-11, and polyamide-6,6. All calculations have been performed with a linearly constrained body. The results have been compared to other theoretical and experimental results if available.

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Section: Resultsmentioning

confidence: 99%

Ab initio calculation of the Young's modulus of α‐polyamides

Peeters¹,

Alsenoy²,

Bartha³

et al. 2002

Int J of Quantum Chemistry

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show abstract

“…form by treatment with aqueous phenol or by stretching at high temperature. [12][13][14][15][16][17][18] The crystal structure of the ( I ! form of nylon 6 was determined by Holmes, Bunn, and Smith,6 and their structure is now commonly accepted.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of nylon 12

Inoue

Hoshino

1973

J. Polym. Sci. Polym. Phys. Ed.

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The crystal structure of nylon 12 prepared by polymerization of dodecalactam has been determined by x‐ray diffraction. Nylon 12 fiber exhibits only the γ form as its stable crystal structure. The unit cell of nylon 12 was determined with the aid of the x‐ray diffraction pattern of a doubly oriented specimen. The unit cell is monoclinic with a = 9.38 Å, b = 32.2 Å (fiber axis), c = 4.87 Å and β = 121.5° and contains four repeating monomer units. The chain is planar zigzag for the most part but is twisted at the position of amide groups, forming hydrogen bonds between neighboring parallel chains. The chain conformation is similar to that of the γ form of nylon 6 proposed by Arimoto. It was deduced from the calculations that there are two chain conformations statistically coexistent according to the direction of twisting. In each conformation, hydrogen bonds are formed between parallel chains to make pleated sheetlike structures. The sheets are nearly parallel to (200) and in the sheet the directions of the neighboring chains are antiparallel, as is the case with nylon 6.

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“…[3,4,11,23] Frequently, fiber samples are annealed to lessen the disorder produced by drawing. [4,9,15,17,21] This is likely a result of reorganization due to thermal mobility. Disorder on drawing a fiber is attributed to statistical or paracrystalline distribution of "up"-"down" chains in some Poly(propylene sulfide)…”

Section: Discussionmentioning

confidence: 98%

A Rule Governing Crystallization of Configurationally Directional Polymers: The Crystal Structure of the α and β Forms of Polypivalolactone

Clark

2007

Journal of Macromolecular Science, Part B

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A "Rule" is proposed for incorporation of polymer chains having directional configuration, e.g. A-B-C-A-B-C, into a crystal. Crystallization into a lamella morphology, as in slow crystallization from the melt, will incorporate antiparallel sequences ("#"#"#). Formation of a fiber by drawing the lamellar morphology must produce a different crystal structure containing parallel directional sequences. The drawn fiber must be polymorphic with a disordered aggregation of antiparallel and parallel crystal polymorphs. An example of this rule is found in the crystal structure of polypivalolactone. The melt crystallized a form is monoclinic, P2 1 /c with a ¼ 9.05Å , b (fiber axis) ¼ 5.97Å , c ¼ 11.69Å , b ¼ 121.48 and consists of planar antiparallel sequences. The molecular conformation is a folded zig-zag arrangement. On drawing a fiber, a disordered second phase of parallel plus antiparallel sequences is created. The chain conformation is a slightly distorted extended zigzag. The crystal structure of the directionally disordered b form is metrically monoclinic, with a ¼ 5.95Å , b ¼ 10.32Å , c (fiber axis) ¼ 4.94Å , b ¼ 101.38. Examples of several classes of crystalline polymers demonstrating this Rule are presented.

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Crystallographic studies of nylon 4. I. Determination of the crystal structure of the α polymorph of nylon 4

Cited by 33 publications

References 8 publications

Ab initio calculation of the Young's modulus of α‐polyamides

Ab initio calculation of the Young's modulus of α‐polyamides

Crystal structure of nylon 12

A Rule Governing Crystallization of Configurationally Directional Polymers: The Crystal Structure of the α and β Forms of Polypivalolactone

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