The evaluation of the structure and hardness of processed plastics by the Vickers microhardness test

Bowman, Jeremy; Bevis, M.

doi:10.1007/bf01776201

Cited by 64 publications

(15 citation statements)

References 24 publications

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“…8). Such a correlation has been previously disputed by several authors [23,27,28]. Figure 11 illustrates the experimental relationship obtained between E and H [15,18] for chain-folded and branched polyethylenes.…”

Section: The Role Of the Non-homogeneous Microphase Relating To The Ementioning

confidence: 77%

A novel concept in describing elastic and plastic properties of semicrystalline polymers: polyethylene

Baltá-Calleja

Kilian

1985

Colloid & Polymer Sci

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An analysis of micro-hardness and elastic modulus data for different iamellar systems in the light of both eutectoid copolymer and chain folded Iamellar microphases is presented. A novel thermodynamically derived expression offering a fair description of hardness (stress required to plastically deform a crystal) of autonomous non-homogeneous microphases in terms of the average crystal thickness, including a defective surface boundary is developed. The present results characterize the mechansim of plastic deformation as primarily governed by the initial mosaic-block structure controlling the "solid state" mechanism underlined. The average dimensions of the remaining blocks after crystal destruction are thus related to the original block dimensions before plastic deformation. Within this context it is shown that the dissipated energy for crystal destruction increases very rapidly with the molar mass-function of crystalline material.The elastic deformation of these lamellar systems at small strains is correlated to the rubber-like behaviour of the cluster-network. Finally, the role of the average thickness of the non-homogeneous microcrystallites is stressed as describing concurrently the elastic and plastics properties of the polymer allowing a quantitative description of the correlation found between micro-hardness and elastic modulus.

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Section: The Role Of the Non-homogeneous Microphase Relating To The Ementioning

confidence: 77%

A novel concept in describing elastic and plastic properties of semicrystalline polymers: polyethylene

Baltá-Calleja

Kilian

1985

Colloid & Polymer Sci

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“…The micromechanical behaviour of ultradrawn PE fibres has been, furthermore, characterized by taking into account the morphological differences between the outer sheath and the inner core of highly oriented PE strands [12,13]. In addition, the MH test has been most efficiently used as a tool for the determination of the varying microstructure details of injection moulded thermoplastics [8,11 ].…”

Section: Introductionmentioning

confidence: 99%

“…Care was taken with the method of specimen mounting and illumination. The recommendations of Bowman and Bevis [11] were followed. Possible edge effects, indentation interactions as well as eventual influence of work hardening was likewise avoided.…”

mentioning

confidence: 99%

Correlation of hardness and microstructure in unoriented lamellar polyethylene

et al. 1981

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The local deformation of the lamellar microstructure of isothermally melted crystallized u noriented polyethylene has been investigated using microindentation hardness (MH). The polymer can be visualized as a composite material consisting of hard and weak elements. The former, the lamellae, are considered to consist of mosaic blocks with liquidlike lattice distortions (paracrystallites). The latter are the interlamellar "amorphous" regions and the mosaic block lateral grain boundaries. The deformation mechanisms beneath the indenter are discussed in the light of current models of plastic deformation. MH is shown to depend on the packing density of the macromolecules in both phases and, as a result, it can be clearly correlated with the macroscopic density of the material. The unit cell expansion and lattice distortions increase in parallel as a consequence of increasing incorporation of chain defects within the lattice. This provokes a conspicuous decrease in the microhardness of the crystals. The increase in lattice distortions is consistent with the concurrent decrease of lamellar thickness and, hence, of the coherently diffracting lattice volume. These results unambiguously emphasize the physical significance of the mosaic block character of the lamellae in determining the micromechanical properties of the material. Finally it is shown that the strain boundary which defines the zone of crystal destruction under the indenter also depends on the average volume of the paracrystallites and on the volume fraction of crystalline material.

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“…For a particular load, three well-defined indentations were measured and the average value (d) was calculated. The Vickers hardness (H v ) numbers were calculated for different loads [15] using the following relation.…”

Section: Mechanical Stability Analysis:-mentioning

confidence: 99%

Non-uniform Spectrum Sensing using Multicoset Sampling.

Raviteja¹,

Subhas.²

2016

IJAR

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The pure and semiorganic material of L-Histidine monohydrochloride dihydrate (LHMHC dihydrate) doped sodium acid phthalate (NaAP) single crystals were effectively grown from deionized water by slow evaporation solution technique. Single crystal X-ray diffraction is employed to know the precise information about the crystallographic structure and also the title materials are orthorhombic crystal system with space group B2ab. The interaction of various functional groups was recognized by FT-IR spectral study. The title materials are optically transparent and having a lower cut-off wavelength as 300 nm, thereby confirming the enhancement of nonlinear optical property and optical band gap of the pure and LHMHC dihydrate doped NaAP crystals have been determined as 3.5 eV and 4 eV by UV-Visible studies. The dielectric constant and dielectric loss of the pure and LHMHC dihydrate doped NaAP crystals decrease as the frequency of applied field increases at the end. The mechanical behaviors of the grown crystals were assessed by Vickers microhardness activities. The SHG efficiency of the grown crystals confirms NLO behavior of green colour emission to offer frequency doubling process for photoelectronic applications.

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The evaluation of the structure and hardness of processed plastics by the Vickers microhardness test

Cited by 64 publications

References 24 publications

A novel concept in describing elastic and plastic properties of semicrystalline polymers: polyethylene

A novel concept in describing elastic and plastic properties of semicrystalline polymers: polyethylene

Correlation of hardness and microstructure in unoriented lamellar polyethylene

Non-uniform Spectrum Sensing using Multicoset Sampling.

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