Multifunctional macromolecular ultrastructures: Introductory Comments Speciality Polymers '86

Ulrich, Donald R.

doi:10.1016/0032-3861(87)90466-6

Cited by 54 publications

(17 citation statements)

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“…The developthat surpasses Kevlar through the stream of the ment of production technology on fiber spinning research of ladder polymers. 1 Poly-p-phenyleneran into serious obstacles. In 1991, Dow decided to benzobisthiazole (PBZT) fiber was developed first.…”

Section: Introductionmentioning

confidence: 99%

Morphological study on poly-p-phenylenebenzobisoxazole (PBO) fiber

Kitagawa

Murase

Yabuki

1998

J. Polym. Sci. B Polym. Phys.

200

140

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Section: Introductionmentioning

confidence: 99%

Morphological study on poly-p-phenylenebenzobisoxazole (PBO) fiber

Kitagawa

Murase

Yabuki

1998

J. Polym. Sci. B Polym. Phys.

200

140

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“…1). [1][2][3][4] These materials exhibit extremely cation of these calculations to polymeric systems high mechanical strength in the direction of the polywill be addressed in a subsequent article.) mer backbone due to the overall rod-like fiber orientation.…”

Section: Introductionmentioning

confidence: 99%

Comparison of computational methods applied to oxazole, thiazole, and other heterocyclic compounds

Shaffer

Wierschke

1993

J Comput Chem

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(A variety of computational methods, including the semiempirical techniques AMI, PM3, and MNDO, and the thermochemical basis sets of Benson and Stine, was used to calculate and compare heats of formation M (A-/i) data for optimized geometries of a variety of aromatic and nonaromatic heterocycles. Detailed analyses, including 6-31G' and MP2/6-31G* ab initio calculations, were performed for the oxazole and thiazole heterocycles. The results indicate a scatter among the methods sensitive to the nature of the heterocycle. This was in particular evident in the oxazole molecule, where AMI gave a singularly high value of WI; consistent with longer calculated bond lengths, particularly about the oxygen atom. Aromatic stabilization energy appears to be addressed differently among the employed methods. Implications of this contrast applied to calculation of macromolecular systems containing heterocyclic units are discussed. INTRODUCTIONthe paraphenylene unit to be a major contributor to the observed differences. Organic heterocycles are becoming increasingly imThis persistently large contrast in heat of formaportant in materials chemistry. Several promising tion results led us to suspect a significant difference • conducting polymers, nonlinear optical polymers, in these computational methods applied to the oxbiomaterials, and high-strength polymers contain azole heterocycle. We thus concentrated our further heterocyclic moieties. In the field of high-strength efforts on the oxazole and the related thiazole het-* polymers, oxazole and thiazole heterocycles are inerocycles to determine which method is most apcorporated into two advanced high-strength polymer propriate for studying these polymers. (The applifibers (Fig. 1).1-4 These materials exhibit extremely cation of these calculations to polymeric systems high mechanical strength in the direction of the polywill be addressed in a subsequent article.) mer backbone due to the overall rod-like fiber orientation.RESULTS AND DISCUSSION There is a great deal of interest in determining the relationship between computationally derived paHeat of Formation Calculations rameters (such as the heat of formation) with ultiHeats of formation data were computed for the oxSmate strength and elastic modulus properties of azole heterocycle using MOPAC 6.0 and an eigenthese polymeric materials. In this context, we pervector following routine for geometry optimization." formed comparative quantum chemical calculationsThe thiazole heterocycle, (the next homologue in the on the cis-PBO structure using the three most commonly employed semiempirical methods (MNDO, chalcogen family) was also examined due to the im-AMI, 6 and PM3) . 7 ' The RHFe optimized geometries portance of thiazole based high-ordered polymers.' o eon rieasiThe results are summarized below in descending or-

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“…The Young's modulus is around 270 GPa, greater than that of steel fibers. PBO had been developed by US Air Force researchers as a super heat resistant polymer that surpasses Kevlar through the stream of the research of ladder polymers [48]. However, the polymer is brittle, undergoing catastrophic fracture at a low elongation of 2-3%.…”

Section: The Polybenzoxazoles (Pbo) Systemmentioning

confidence: 99%

Dispersion and Reinforcement of Nanotubes in High Temperature Polymers for Ultrahigh Strength and Thermally Conductive Nanocomposites

Yang¹

2007

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Multifunctional macromolecular ultrastructures: Introductory Comments Speciality Polymers '86

Cited by 54 publications

References 0 publications

Morphological study on poly-p-phenylenebenzobisoxazole (PBO) fiber

Morphological study on poly-p-phenylenebenzobisoxazole (PBO) fiber

Comparison of computational methods applied to oxazole, thiazole, and other heterocyclic compounds

Dispersion and Reinforcement of Nanotubes in High Temperature Polymers for Ultrahigh Strength and Thermally Conductive Nanocomposites

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