Deformation mechanisms in oriented high-density polyethylene

Young, Robert J.; Bowden, P. B.; Ritchie, Jenny; Rider, J. G.

doi:10.1007/bf00755579

Cited by 196 publications

(117 citation statements)

References 5 publications

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“…In this meaning, this model might be extended to evaluate yield stress as a function of composition. As for more detailed deformation mechanisms in semicrystalline polymers, however, it is necessary to take into account of irreversible shear deformation of lamellae, as demonstrated by Young et al 26 In the case of the miscible blends, therefore, yielding can be analyzed using the bending behavior of a layered composite model in which an amorphous phase is sandwiched between adjacent lamellar plates. The theoretical treatment for the bending stress and the flexural modulus for a simple laminate model is exemplified in Appendix A.…”

Section: Yielding Behaviormentioning

confidence: 99%

Role of tie molecules in the yielding deformation of isotactic polypropylene

Nitta

Takayanagi

1999

J. Polym. Sci. B Polym. Phys.

129

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We examined the effects of the tie‐molecule fraction on the yielding behavior of two isotactic polypropylenes, one having little ethylene content and the other as the homopolymer with no ethylene. The tie‐molecule fraction of the samples used in this study was controlled by blending ethylene‐α‐olefin of an α‐olefin content above 50 mol % in the blend of which the copolymers were incorporated into the amorphous regions of polypropylene (PP). An excellent linear relationship was observed between the measured yield stress and the tie‐molecule fraction estimated from the Huang–Brown model, suggesting that the tie‐molecule fraction and lamellar stiffness determine whether the lamellar fragmentation is easily activated or not, depending on the PP composition. Furthermore, an extended Huang–Brown model predicts a lamellar cluster connecting about five lamellae, which has a potential to account for morphological transformation of the spherulitic structure into a fibrillar one. Comparing the immiscible blends showing a phase‐separated morphology with the partially miscible blends mentioned above, the yield stress was lowered by the presence of rubber phase, apparently in a similar manner; but the yielding processes were clearly discriminated between both cases when the yield stress was plotted against the tie‐molecule fraction. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 357–368, 1999

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Section: Yielding Behaviormentioning

confidence: 99%

Role of tie molecules in the yielding deformation of isotactic polypropylene

Nitta

Takayanagi

1999

J. Polym. Sci. B Polym. Phys.

129

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“…However, experimental measurement of residual micro-stresses in polymeric system (Young et al 1973;Balasingh and Singh 1997) is limited. Hence an attempt has been made in this investigation to study the neutron-induced microstress in polymer fibre applying X-ray diffraction.…”

Section: Introductionmentioning

confidence: 99%

Analysis of microstress in neutron irradiated polyester fibre by X-ray diffraction technique

2005

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Abstract. Microstresses developed in the crystallites of polymeric material due to irradiation of high-energy particle causes peak broadening and shifting of X-ray diffraction lines to lower angle. Neutron irradiation significantly changes the material properties by displacement of lattice atoms and the generation of helium and hydrogen by nuclear transmutation. Another important aspect of neutron irradiation is that the fast neutron can produce dense ionization at deep levels in the materials. The polyethylene terephthalate (PET) fibre of raw denier value, 78⋅ ⋅2, were irradiated by fast neutron of energy, 4⋅ ⋅44 MeV, at different fluences ranging from 1 × × 10 9 n/cm 2 to 1 × × 10 12 n/cm 2 . In the present work, the radiation heating microstresses developed in PET micro-crystallites was investigated applying X'Pert-MPD Philips Analytical X-ray diffractometer and the effects of microstresses in tensile strength of fibre measured by Instron have also been reported. The shift of 0⋅ ⋅45 cm -1 in the Raman peak position of 1614⋅ ⋅65 cm -1 to a higher value confirmed the development of microstresses due to neutron irradiation using micro-Raman technique. The defects due to irradiation were observed by SEM micrographs of single fibre for virgin and all irradiated samples.

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“…During cold drawing, the crystals tend to fail along the mosaic boundaries and then break into folded chain blocks that in turn serve as building elements of the new polymer network structure. 10,11 If the test is stopped in the constant-load region of the load-extension curve, the drawn region or the neck of the specimen will suffer an extension corresponding to the natural draw ratio. Figure 1 shows the plot of natural draw ratio of the extrudates against drawing speed.…”

Section: Drawing Behavior Of Ppmentioning

confidence: 99%

Study on poly(ethylene terephthalate)/polypropylene microfibrillar composites. II. Solid‐state drawing behavior

Lin

Jia

Leung

et al. 2004

J of Applied Polymer Sci

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A (20/80) blend of poly(ethylene terephthalate)/polypropylene (PET/PP) was solid-state drawn to enhance the molecular orientation of the PET microfibers. Effects of drawing temperature (23-140°C) and drawing speed (max. 1000 mm/min) on the morphology and draw ratio of the blend were studied and discussed based on the drawing behaviors of the pure polymers. In cold drawing, there seemed to be a critical drawing speed below which the natural draw ratios of the polymers remained constant, but above which the draw ratios first decreased slightly because of suppression of molecular relaxation and then increased because of breakage of highly strained molecules and disintegration of lamellar crystals into finer mosaic blocks. Macroscopically, the pure PP and the PET/PP composite extrudates gave similar draw ratios at the same speeds. SEM showed that the PET microfibers suffered a smaller elongation than the PP matrix and severe voiding occurred at the PET/PP interface. Furthermore, substantial fiber breakage occurred during cold drawing at speeds above 200 mm/ min. In comparison, drawing at 100°C caused no obvious interfacial voiding and fiber breakage. Furthermore, the natural draw ratio of the blend was lower than that of the pure PP extrudate, indicating that the PET microfibers had constrained the deformation of the PP matrix.

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Deformation mechanisms in oriented high-density polyethylene

Cited by 196 publications

References 5 publications

Role of tie molecules in the yielding deformation of isotactic polypropylene

Role of tie molecules in the yielding deformation of isotactic polypropylene

Analysis of microstress in neutron irradiated polyester fibre by X-ray diffraction technique

Study on poly(ethylene terephthalate)/polypropylene microfibrillar composites. II. Solid‐state drawing behavior

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