Experiences with modified test conditions for notch pipe testing

Kratochvilla, Thomas R.; Muschik, H.; Dragaun, H.

doi:10.1016/j.polymertesting.2007.09.006

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…The internal defects of the material cause localized plastic yielding that eventually result in the initiation of craze. As the strain increases, the craze extends to form numerous highly oriented microfibrils, which help to reduce the stress concentration in the crack‐tip region . Over a longer time, the highly oriented load‐bearing tie chain networks of microfibrils within the craze start to relax and untangle from each other until the number of remaining linkages becomes extremely small.…”

Section: Resultsmentioning

confidence: 99%

“…As the strain increases, the craze extends to form numerous highly oriented microfibrils, which help to reduce the stress concentration in the crack-tip region. 4,[17][18][19][20] Over a longer time, the highly oriented load-bearing tie chain networks of microfibrils within the craze start to relax and untangle from each other until the number of remaining linkages becomes extremely small. When the highly stretched amorphous network built up by intermicrofibrillar tie chains cannot continue to withstand the high stress, the fibrils within the craze will break, and brittle fracture of the material occurs.…”

Section: Tensile and Bending Testmentioning

confidence: 99%

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Influence of comonomer distribution on crystallization kinetics and performance of polyethylene of raised temperature resistance

Zhang

Bing

Ding

et al. 2019

Polymer International

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Three polyethylene of raised temperature resistance (PE‐RT) materials have been used to explore the factors that cause the differences in crystallization kinetics and mechanical performance between different classes and between the same classes. 1‐PE‐RT and 3‐PE‐RT belong to the same class (type II) but with different comonomer, while 2‐PE‐RT (type I) and 3‐PE‐RT use the same comonomer. The results of tensile and bending tests and isothermal crystallization indicate that different classes or even the same classes of PE‐RT have differences in high‐temperature resistance and long‐term performance. Characterization of the molecular chain structure shows that the comonomer content within the high molecular weight chains is significantly higher than that within the low molecular weight chains, and the comonomer is not uniformly distributed over the short‐chain molecules, which makes 1‐PE‐RT have higher modulus and better long‐term performance. Because the difference of comonomer content in long‐chain molecules and short‐chain molecules is small and the comonomer is relatively uniformly distributed over the short‐chain molecules, 3‐PE‐RT cannot balance the stiffness and the long‐term performance very well. For 2‐PE‐RT, the comonomer content in the long‐chain molecules and the short‐chain molecules is approximately the same and there is no intramolecular comonomer distribution, and thus it has the best long‐term performance but the lowest modulus. 2‐PE‐RT cannot have rigidity and good long‐term performance at the same time. © 2019 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Tensile and Bending Testmentioning

confidence: 99%

Influence of comonomer distribution on crystallization kinetics and performance of polyethylene of raised temperature resistance

Zhang

Bing

Ding

et al. 2019

Polymer International

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“…La résistance à la propagation de fissure est amplement influencée par l'état et la grandeur de ces contraintes résiduelles. En outre, il a été montré que la propagation de fissures est plus lente dans les couches externes soumises à des contraintes résiduelles de compression [20,21]. Pour les mesures des déformations à la rupture ε f , les corrélations avec la limite d'élasticité ne sont pas toujours évidentes comme montré dans la figure 9.…”

Section: Bases Théoriquesunclassified

Étude des propriétés mécaniques à travers la paroi d’un tube HDPE-80 extrudé destiné à la distribution du gaz naturel

Alimi

Ghabeche

Chaoui

et al. 2012

Matériaux & Techniques

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-Les polymères constituent une famille remarquable de matériaux de par l'extrême variété des produits qu'il est possible d'en concevoir et la flexibilité des différents procédés de mise en oeuvre. Le recours à ces matériaux a permis de réaliser des gains substantiels sur les coûts, les délais d'utilisation et les interventions. En dépit de l'acceptation du polyéthylène comme alternative économique pour les réseaux de tubes, la sûreté de fonctionnement reste une question fondamentale, et son utilisation requiert l'aptitude à déterminer les propriétés intrinsèques en fonction de l'utilisation et des conditions de service requises par le dimensionnement. Cette étude traite la détermination du comportement mécanique d'une résine HDPE à travers la totalité de l'épaisseur d'un tube à gaz. Des éprouvettes normalisées ont été usinées dans des conditions spécifiques suivant la norme ISO-527 dans le sens longitudinal. Les propriétés mécaniques sont mesurées en traction sur une machine asservie et pilotée par ordinateur. Les résultats indiquent qu'il y a une nette évolution des propriétés mécaniques à travers la paroi tubulaire, ce qui confirme le comportement observé dans d'autres études relatives à des filaments de polyéthylène testés dans les mêmes conditions. Ces variations sont imputées aux gradients morphologiques et à l'évolution des contraintes internes imparties par le procédé d'extrusion.

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“…Tests carried out by conventional destructive methods provide information on the structure and mechanical characteristics of the virgin material or estimate them after a certain operation interval in different loading conditions and environments [1][2][3][4]. In order to achieve a product, in many cases the material choice is influenced by its long term properties [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Temperature and heat effects on polyethylene behaviour in the presence of imperfections

Murariu

Šajić²

2016

THERM SCI

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This paper highlights the changes of polyethylene behaviour during various loading rates as well as the influence of test temperature on the material characteristics. Passive infrared thermography method and a high speed infrared camera were used to observe the temperature changes of the sample surface during the tests. The experimental program was carried out on samples taken from PE80 polyethylene gas pipes with simulated imperfections with bilateral V-notch, U-notch, and central hole. Samples have been tensile tested and the results are correlated with the temperature distribution of the samples surface.

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Experiences with modified test conditions for notch pipe testing

Cited by 6 publications

References 2 publications

Influence of comonomer distribution on crystallization kinetics and performance of polyethylene of raised temperature resistance

Influence of comonomer distribution on crystallization kinetics and performance of polyethylene of raised temperature resistance

Étude des propriétés mécaniques à travers la paroi d’un tube HDPE-80 extrudé destiné à la distribution du gaz naturel

Temperature and heat effects on polyethylene behaviour in the presence of imperfections

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