Structural Basis of High‐Strength High‐Modulus Polymers

Marikhin, V. A.; Myasnikova, L. P.

doi:10.1002/9783527615056.ch2

Cited by 17 publications

(16 citation statements)

References 112 publications

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“…In the necking zone, a transformation from a spherulitic structure into a fibrillar structure takes place. 14 The spherulites are deformed irreversibly. Chains can unfold by intralamellar shear or melt locally.…”

Section: Ftir Characterization Of the Basic Componentsmentioning

confidence: 99%

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Huy

Luepke

Radusch

2001

J. Appl. Polym. Sci.

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To clarify the deformation mechanisms and to improve the mechanical properties of dynamic vulcanizates, we studied their deformation behavior by Fourier‐transform infrared (FTIR) spectroscopy. It was found that the orientation in the dispersed phase (EPDM phase) is higher than in the matrix (PP phase) upon loading. The orientation of the rubber phase increases continuously. In the thermoplastic phase, a change of the deformation mechanism takes place. With respect to the total strain of the material, the orientation in the thermoplastic phase of the dynamic vulcanizates is lower, and in the elastic phase, it is higher than the corresponding orientation of the pure components. During stress relaxation, there is an increase of the orientation in the crystalline PP phase. Simultaneously, a decrease of the orientation in the EPDM phase is observed. Upon unloading, the orientation recovery in the EPDM phase is always complete, while the orientation recovery in the PP phase is reversible only at low strains. The critical point, where the elastic deformation gets lost, corresponds to the minimum in the orientation function curve. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 148–158, 2001

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Section: Ftir Characterization Of the Basic Componentsmentioning

confidence: 99%

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Huy

Luepke

Radusch

2001

J. Appl. Polym. Sci.

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“…High-performance oriented polymer materials are promising materials in various fields of application. One of the effective methods of their production is the drawing of isotropic low-strength polymers [ 1 ]. The initial lamellar crystallites in isotropic polymers are transformed in the course of orientation into rigid oriented fibrils due to the unfolding of the polymer chain folds in the initial lamellae.…”

Section: Introductionmentioning

confidence: 99%

“…The initial lamellar crystallites in isotropic polymers are transformed in the course of orientation into rigid oriented fibrils due to the unfolding of the polymer chain folds in the initial lamellae. Such a discrete “structural re-arrangement” leads to a significant (by an order of magnitude or more) increase in the material important mechanical characteristics —Young’s (or elastic) modulus ( E ) up to 200 GPa and strength ( σ ) up to 6 GPa [ 1 , 2 , 3 ]. The advantage of such materials with respect to high-performance inorganic materials lies in their extremely high specific characteristics (related to the material density ρ ).…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of the Mechanical Behavior of High-Performance Polymers: Weibull’s or Gaussian Distributions?

2022

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This work addresses the following problem: which of the statistical approaches, Weibull’s or Gaussian, is more appropriate to correctly describe the statistical distributions of the mechanical properties of the high-performance polymer materials of different sample types (single or multifilament oriented fibers) and chain architectures (ultra-high-molecular-weight polyethylene, polyamide 6, or polypropylene)? Along with the routine mechanical properties such as strength, strain at break, and Young’s modulus, an apparent viscoelastic modulus and an apparent strain at break found when differentiating the stress–strain curves have been considered for the first time. For this purpose, a large sample number (50 in each series) has been tested. It has been shown that the values of the Weibull’s modulus (m) characterizing the data scatter were dependent both on the chain architecture and the sample type for the five elastic, viscoelastic and fracture characteristics analyzed. The Weibull’s model has been found to be more correct as compared to the Gaussian one. The different statistical approaches used for the analysis of the large arrays of the data are important for a better understanding of the deformation and fracture mechanisms of quasi-brittle and quasi-ductile high-performance polymer materials.

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“…Currently, it is generally accepted that thermal prehistory plays a very important role in polymer strengthening by orientational drawing [1]. However, it was not so clear in the 1960s.…”

Section: Introductionmentioning

confidence: 99%

ON THE MEMORY EFFECT IN UHMWPE NASCENT POWDERS^*

Иванькова

Myasnikova

Marikhin

et al. 2001

Journal of Macromolecular Science, Part B

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Morphology and molecular structure of three nascent ultra high molecular weight polyethylene (UHMWPE) powders synthesized on unsupported and supported Ziegler-Natta heterogeneous catalysts were studied with the help of electron microscopy and infrared (IR) spectroscopy. A synthesis was carried out in a slurry process in n-heptane at a temperature of about 70°C, which resulted in production of UHMWPE of one and the same molecular weight, approaching 10 6 g/mol. The morphology of the nascent particles dramatically differed, however, which is evidence of the important role of the catalytic system used. Nascent particles synthesized on unsupported TiCl 4 catalyst with EtAl as the cocatalyst had a globular structure, while those synthesized on supported TiCl 4 /Al 2 O 3 ؒSiO 2 and TiCl 3 ؒ0.3 AlCl 3 /MgCl 2 Ziegler-Natta catalysts with the same cocatalyst demonstrated fibrillar (cobweb) and spiral (wormlike) structures, respectively. As revealed by IR spectroscopy, there was a significant difference in the nature of the crystalline regions formed during the synthesis/crystallization process; in the amount of short trans sequences not included in crystallites (taut tie molecules); in the content of irregular conformers of various types, including typical point de-*Dedicated to Prof. Francisco J. Baltá Calleja on the occasion of his 65th 814 IVAN'KOVA ET AL.fects 2G1 kinks; and so on. The melt-crystallized films produced from the investigated reactor powders were markedly distinguished by their drawability and by the existence and the amount of different molecular conformations despite a sufficiently high recrystallization temperature and prolonged preheating. The difference in molecular structure of the drawn films was retained in a whole range of draw ratios. It is concluded that there is a well-pronounced "memory effect" and the morphology of the original nascent particles depending on the catalyst/synthesis conditions clearly play a role in the properties of the end product.

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Structural Basis of High‐Strength High‐Modulus Polymers

Cited by 17 publications

References 112 publications

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Statistical Analysis of the Mechanical Behavior of High-Performance Polymers: Weibull’s or Gaussian Distributions?

ON THE MEMORY EFFECT IN UHMWPE NASCENT POWDERS^*

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Structural Basis of High‐Strength High‐Modulus Polymers

Cited by 17 publications

References 112 publications

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

Statistical Analysis of the Mechanical Behavior of High-Performance Polymers: Weibull’s or Gaussian Distributions?

ON THE MEMORY EFFECT IN UHMWPE NASCENT POWDERS*

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Product

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ON THE MEMORY EFFECT IN UHMWPE NASCENT POWDERS^*