Phase Transformation and Deformation Processes in Oriented Polyethylene

Seto, Tsuneo; Hara, Takehisa; Tanaka, Kenzö

doi:10.1143/jjap.7.31

Cited by 254 publications

(126 citation statements)

References 7 publications

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“…It is known that a force larger than the critical value is necessary for the phase transition to a monoclinic phase. 96 Therefore, this result indicates that an external force beyond the critical value was applied in the region 10 mm away from the indenter tip-polymer interface. It should also be noted that the crystal in the region nearest the tip-polymer interface shows no monoclinic phase but the slight broadening of the crystal orientation by plastic deformation, indicating that the stress is not well applied in this region.…”

Section: Indentationmentioning

confidence: 79%

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

Nozue

Shinohara

Amemiya

2007

Polym J

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ABSTRACT:With the recent development of an X-ray source, focusing optics, and X-ray detectors, microbeam Xray scattering techniques have been well established and widely applied to the characterization of polymeric materials. Microbeam X-ray scattering is a unique and powerful tool that provides abundant information on local structures, such as the spatial inhomogeneity of materials and the structural change at a local position. Furthermore, by combining microbeam small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), the observable spatial scale range is from several to several hundred Å , which is the most important scale range in the hierarchical structure analyses of polymers. In this review, the representative applications of microbeam X-ray scattering to polymer crystallization, spatial inhomogeneity analyses, stress transfer under external field and the microphase separated structure analyses in block copolymer systems are introduced. [doi:10.1295/polymj.PJ2007077] KEY WORDS Microbeam Small-and Wide-angle X-ray Scattering / Polymer Characterization / X-Ray scattering techniques are widely applied to the observation of various polymer structures. X-Ray scattering is mainly classified into small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), depending on the scattering angle. As is easily understood by using the Bragg formula ( ¼ 2d sin ), when the scattering angle 2 decreases, scattering reflects a large structure. SAXS, which is X-ray scattering at small angle (< 2, 3) region, provides information on nanostructures in a size range of several to several ten nanometers. In the field of polymeric materials, SAXS is typically applied to obtaining information on crystalline lamella stacking structures, 1,2 various microphase separated structures in block copolymer systems, 3,4 and organic-inorganic composite structures. 5,6 On the other hand, WAXS is typically applied to obtaining information on sub-nanometerscale structures, such as crystal packing and amorphous structures.To determine the structural characteristics of polymeric materials in detail, it is also very important to understand the formation and/or deformation mechanisms of such materials. Although X-ray scattering experiments were limited to the static measurements in laboratory X-ray sources until early 1980s, the advent of a synchrotron X-ray source and the development of X-ray detectors 7-13 have enabled us to observe a one-or two-dimensional scattering pattern within a second, making it possible to perform timeresolved X-ray scattering measurements for various structural changes, such as crystallization, 14-17 structural changes due to deformation [18][19][20][21][22][23] and phase transition due to temperature change. [24][25][26] While many polymeric materials exhibit spatial inhomogeneity on a micrometer scale, conventional X-ray scattering techniques provide the information that is spatially averaged over more than hundreds micrometer of the sample area irradiated by X-ray beam. Structural inmhom...

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Section: Indentationmentioning

confidence: 79%

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

Nozue

Shinohara

Amemiya

2007

Polym J

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“…Twinning and phase transition have been shown to occur in the early stage of plastic deformation of PE [1,4,[34][35][36][37]. Such structural changes, often observed during the solid state forming of metals, are typically shear-driven phenomena that can only be accounted for on crystallographic grounds.…”

Section: Strain-induced Phase Transitionmentioning

confidence: 99%

Plasticity of semi-crystalline polymers: crystal slip versus melting-recrystallization

Séguéla¹

2007

E-Polymers

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Semi-crystalline polymers can be drawn up to very high draw ratios that involve a complete molecular rearrangement of the chain-folded lamellar morphology into a more or less chain-unfolded fibrillar microstructure. This metamorphosis is likely to take place through an intermediate state of high molecular disorder at a local scale. This is the reason why some authors talk of a strain-induced melting-recrystallization process. In contrast, several structural features occurring at moderate plastic strains are relevant to strictly crystallographic processes. A critical discussion of experimental findings and theoretical approaches is made for pointing out the strength or the deficiency of the different author argumentations. No doubt that both phenomena can occur: crystallographic processes are active at all strain levels whereas meltingrecrystallization is restricted to the post-yield stage accompanied with chain unfolding. Melting-recrystallization is rather a corollary of chain unfolding than a basic mechanism of the plastic deformation. Besides, it may concern only a part of the crystalline phase and can be inhibited under adequate deformation conditions.

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“…The metastable crystalline form of polyethylene usually Turner-Jones [3] is triclinic with a=0.4285nm, b=0.4820nm, c=0.254nm, a=90°, 8=110.25°, y=108°, whereas that proposed by Seto, Hara, and Tanaka [4] is monoclinic with a=0.809nm, b=0.253nm, c=0.479nm and 8=107.9°. The indices of the 0.45^, 0.38q, and 0.35^r eflections based on the triclinic cell [3] are 010, 100 and 110 respectively.…”

mentioning

confidence: 98%

“…Figure 4 Strain during recovery (log-log coordinates) from experiments done at constant applied stress but varied t^. The dashed lines represent the recovery predicted using equation lb.…”

mentioning

confidence: 99%

“…The residual strains in the released samples were of course larger the higher the initially imposed strain, and ranged from 0.2 to 3.0. Among the features which were observed in all these samples [1,2] was the presence of a small proportion of crystallites exhibiting wide angle x-ray reflections characteristic of the metastable crystalline form of polyethylene [3,4], The structure of the remaining majority of the crystallites was the normal orthorhombic structure [5].…”

mentioning

confidence: 99%

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Relationship between morphology and mechanical properties of ultra high molecular weight polyethylene

Crissman¹,

Khoury²

1983

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Phase Transformation and Deformation Processes in Oriented Polyethylene

Cited by 254 publications

References 7 publications

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

Plasticity of semi-crystalline polymers: crystal slip versus melting-recrystallization

Relationship between morphology and mechanical properties of ultra high molecular weight polyethylene

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