The brittle‐ductile transition in linear polyethylene

Mandelkern, L.; Smith, Fiona; Failla, Marcelo Daniel; Kennedy, M. A.; Peacock, Andrew J.

doi:10.1002/polb.1993.090310416

Cited by 30 publications

(17 citation statements)

References 10 publications

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“…and hereafter commented are those calculated according to Eqn (based on the use of the 1305 cm −1 band), i.e. the most reliable to this scope . In fact, the very broad C─C stretching band at 1080 cm −1 , on which Eqn relies, has been found to vary in shape and height depending on crystallization conditions as well as on the gauche‐trans ratio and hence appeared unsuitable for computer analysis .…”

Section: Resultsmentioning

confidence: 99%

“…the most reliable to this scope . In fact, the very broad C─C stretching band at 1080 cm −1 , on which Eqn relies, has been found to vary in shape and height depending on crystallization conditions as well as on the gauche‐trans ratio and hence appeared unsuitable for computer analysis . The band at 1305 cm −1 has a sounder theoretical basis and has been found to be adequate for the analysis of the polyethylene liquid‐like phase …”

Section: Resultsmentioning

confidence: 99%

“…The α a amorphous content was calculated also by another equation (based on the 1305 cm −1 band), which has been demonstrated to be more reliable than Eqn , based on the 1080 cm −1 band:…”

Section: Methodsmentioning

confidence: 99%

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Comparative micro‐Raman study on standard, cross‐linked and vitamin E‐blended polyethylene acetabular cups after long‐term in vitro testing and ageing

Taddei

Pavoni

Affatato

2017

J Raman Spectroscopy

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Ultra‐high molecular‐weight polyethylene has been used in total joint replacement for the last three decades. Many attempts have been made to improve the wear behaviour of this material. Highly cross‐linked polyethylene (XLPE) has been developed to decrease the wear rate, while the addition of stabilizers such as vitamin E has been proposed to slow the oxidation processes. In this study, we compared the wear behaviour of conventional ultra‐high molecular‐weight polyethylene, XLPE and vitamin E‐added XLPE acetabular cups for total hip arthroplasty. The samples were run for five million cycles on a hip joint simulator (first test), then underwent an accelerated ageing treatment, were tested again for two million cycles (second test) and finally were run for another two million cycles in presence of third‐body particles (third test). Our study showed that vitamin E‐added XLPE cups had a better wear behaviour only in the long‐term and more severe testing conditions: in the third test, they underwent the lowest increase in wear rate. Micro‐Raman spectroscopy allowed us to analyse the wear degradation of the cups on a molecular scale, and differences in the wear mechanisms were revealed. The presence of vitamin E did not prevent structural changes upon the first test, while it did in ageing and in the second test. In the third test, more significant structural changes were observed; the XLPE cups, which lost the lowest mass, had the most modified articular surface. These morphological aspects should be taken into account, together with gravimetric wear rates, in the characterization of wear degradation. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Comparative micro‐Raman study on standard, cross‐linked and vitamin E‐blended polyethylene acetabular cups after long‐term in vitro testing and ageing

Taddei

Pavoni

Affatato

2017

J Raman Spectroscopy

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“…The interpretation given was in terms of chain-folded crystals melting and recrystallizing to an extended chain form, followed by remelting. 5 The above is a tentative explanation for the behavior shown in Figure 6. We performed preliminary annealing experiments to explore the nature of the exothermic peaks in the scans at 1°C/min and 5"C/ min.…”

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confidence: 76%

Phase transitions in two polyesters containing a smectic diol

Khan

Patel

Bashir

et al. 1995

J Polym Sci B Polym Phys

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This work reports the phase behavior of the polyesters made from the condensation of isophthalic acid (IA) and terephthalic acid (TA) with the mesogenic diol 4,4′‐bis (6‐hydroxy hexoxy) biphenyl (BHHBP). The latter monomer forms a smectic mesophase in the interval 98‐179°C. Fischer et al., who investigated the room temperature x‐ray patterns of the oriented polyesters of BHHBP and IA, as well as BHHBP and TA, claimed that both polymers also showed smectic mesophases. However, they showed no other evidence to support their interpretation. In the present work, examination of these polyesters under the optical microscope revealed focal conic textures for the IA polyester, but spherulitic textures for the TA polyester. DSC studies revealed thermograms with two peaks in the cooling scan for the IA polyester, at different cooling rates, which supported the view that there were two phase transitions. The heating scans of the TA polyester showed multiple peaks that depended on heating rate whereas on cooling, only a single exothermic peak was observed at all cooling rates. Thus, the current results definitely support the case for a smectic A mesophase in the IA polyester but, contrary to Fischer et al.'s opinion, do not suggest any mesophase formation in the TA polyester. © 1995 John Wiley & Sons, Inc.

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“…on a diamond lattice initiated at a site x, y, 0 on z s 0. The first step of the walk takes either a or 1 a with equal probabilities to step into the amor- 3 phous region and forms a trans with its two pre-Ž ceding bonds in the crystal. i.e., the interface is assumed to be normal to the crystalline chains in .…”

Section: Diamond Lattice and Random Walksmentioning

confidence: 99%

Loop entanglement of semicrystalline polyethylene in amorphous region: Diamond lattice approach

Duan

Howard

1999

J. Comput. Chem.

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Linear polyethylenes in the amorphous region have been simulated as restricted random walks on a diamond lattice between two absorbing planes. The links among loops were studied by treating loops as oriented curves. The local conformations of polyethylene chains (i.e., trans and gauche energy differences) were considered in the simulation, thereby determining the effect of crystallization temperature on the loop entanglement. It was found that the total Gauss winding and link density of linked loops increased with the thickness of the amorphous region. This result agrees with that of the cubic lattice model. The link probability decreases very slowly with the thickness of the amorphous region. On the other hand, the results presented clearly indicate that all statistical measures of linked loops decrease with temperature. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 348–353, 1999

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The brittle‐ductile transition in linear polyethylene

Cited by 30 publications

References 10 publications

Comparative micro‐Raman study on standard, cross‐linked and vitamin E‐blended polyethylene acetabular cups after long‐term in vitro testing and ageing

Comparative micro‐Raman study on standard, cross‐linked and vitamin E‐blended polyethylene acetabular cups after long‐term in vitro testing and ageing

Phase transitions in two polyesters containing a smectic diol

Loop entanglement of semicrystalline polyethylene in amorphous region: Diamond lattice approach

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