Two types of crazing realized in the course of strain of polymers

Volynskiĭ, A. L.; Shmatok, Ye.A.; Ukolova, Ye.M.; Аржакова, О.В.; Yarsheva, L.M.; Луковкин, Г.М.; Bakeyev, N.F.

doi:10.1016/0032-3950(91)90158-m

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…It is also possible that both opaque white neck and translucent neck are caused by craze formation, with the former by the classical crazes that are developed in discrete regions but the latter by the so‐called “delocalized” crazes that consist of tiny pores of uniformly distributed through the whole volume. However, not much work is available in the literature about the concept of “delocalized” craze, and at this stage, it is not clear whether the delocalized craze is just another expression for the cavity generated by hydrostatic tension.…”

Section: Resultsmentioning

confidence: 99%

Transition of neck appearance in polyethylene and effect of the associated strain rate on the damage generation

Jar

2013

Polymer Engineering & Sci

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By reducing tensile test speeds over four orders of magnitude, from 5 to 0.001 mm/min (corresponding to the initial strain rate of 4 3 10 23 to 8 3 10 27 s 21 ), color of polyethylene (PE) specimens remains translucent during the necking process, no longer changing to opaque white. Since changing the color to opaque white indicates the presence of cavities, the unchanged color suggests that such cavitation process is avoided by reducing the crosshead speed. With this discovery, the study proceeds to investigate the mechanical behavior of PE specimen shown at two crosshead speeds, 1 and 0.001 mm/min, before neck is developed; the former crosshead speed leads to opaque white neck but the latter translucent. The results show that at 1 mm/min, a stretch corresponding to a strain smaller than 4% can cause degradation of mechanical properties. Since this level of deformation is close to that allowed in service, the study recommends the consideration of in-service loading rate for evaluation of the mechanical properties, especially for long-term applications such as plastic pipes for natural gas transportation. POLYM. ENG. SCI., 54:1871-1878, 2014

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Section: Resultsmentioning

confidence: 99%

Transition of neck appearance in polyethylene and effect of the associated strain rate on the damage generation

Jar

2013

Polymer Engineering & Sci

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“…In addition to the classical crazing described above, for which the stages of development of individual crazes can be clearly observed, there is another kind of deformation of polymers in liquid media: delocal ized crazing [33,34]. If classical localized crazing is more typical for amorphous glassy polymers, the delocalized crazing is characteristic only for crystalline polymers.…”

Section: Solvent Crazing As a Methods For Preparing Polymers With Nanomentioning

confidence: 99%

Crazing as a method for preparation of polymer blends

et al. 2012

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Publications on the development of a new universal method for the preparation of poly mer-polymer blends are reviewed. This approach is based on the phenomenon of solvent crazing, which comes into play in the tensile drawing of polymers in the presence of adsorption active liquid media. It is important that solvent crazing is accompanied by the development of a unique fibillarporous structure, in which the dimensions of craze pores and fibrils do not exceed several tens of nanometers. Two approaches to the preparation of the polymer-polymer blends are described. According to the first approach, the nanoporous structure of the solvent crazed polymer is filled with the monomer, and its further in situ polymerization results in the polymer-polymer blends. The sec ond approach has been recently advanced by the authors of this publication; it involves direct penetra tion of macromolecules into the formed fibillar-porous structure of the solvent crazed polymer. Both approaches are capable of producing diverse polymeric blends with a high degree of mutual dispersion of the components. The above materials are shown to be characterized by specific mechanical, elec trical, and adsorption properties, which are due to the unique fibillar-porous structure of the solvent crazed polymer. The composition, structure, and properties of the prepared blends are controlled by the mechanism of solvent crazing and by the deformation conditions of the initial polymer. Several aspects of the practical application of the polymer blends prepared via the mechanism of solvent craz ing in adsorption active liquid media are reviewed. Fig. 5. Electron micrographs of nanocomposite HDPE-PMMA (tensile strain in the monomer, 200%) after the selective washing of (a) HDPE and (b) PMMA.

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A new method to evaluate solvent stress cracking

Cornélis

Kander

1996

Polymer Engineering & Sci

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The effect of crystallinity on the crazing process in isotactic polypropylene (i‐PP) was investigated by using a new static crazing experiment. Strips of i‐PP films are stressed in glass cones, which are placed into a series of solvents. Characterization of the films was performed by hot‐stage optical microscopy, scanning electron microscopy, wide‐angle X‐ray scattering, differential scanning calorimetry, and contact angle goniometry. The affinities of the solvents for the polymer were investigated by dynamic solvent uptake measurements. Crazing experiments revealed that both the sample preparation and the solvent choice play an important role in the crazing process. A “good” solvent is shown to be a “bad” crazing agent, whereas an intermediate solvent behaves as a “good” crazing agent. Two opposite processes are shown to take place: appearance of void and solvent‐induced crystallization.

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Two types of crazing realized in the course of strain of polymers

Cited by 3 publications

References 8 publications

Transition of neck appearance in polyethylene and effect of the associated strain rate on the damage generation

Transition of neck appearance in polyethylene and effect of the associated strain rate on the damage generation

Crazing as a method for preparation of polymer blends

A new method to evaluate solvent stress cracking

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