Crack propagation in PE-HD induced by environmental stress cracking (ESC) analyzed by several imaging techniques

Schilling, Markus; Niebergall, Ute; Alig, Ingo; Oehler, Harald; Lellinger, Dirk; Meinel, Dietmar; Böhning, Martin

doi:10.1016/j.polymertesting.2018.08.014

Cited by 17 publications

(50 citation statements)

References 19 publications

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“…ESC relates to an accelerated brittle failure of a polymer, resulting from low-to-moderate stresses while in contact with fluids such as alcohols or detergents [9][10][11][12][13][14][15][16]. It is considered a physical phenomenon since the polymer chains are not chemically altered [17].…”

Section: Introductionmentioning

confidence: 99%

Studying the mechanism of biodiesel acting as an environmental stress cracking agent with polyethylenes

Saad

Abdulhussain

Gomes

et al. 2020

Polymer

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Section: Introductionmentioning

confidence: 99%

Studying the mechanism of biodiesel acting as an environmental stress cracking agent with polyethylenes

Saad

Abdulhussain

Gomes

et al. 2020

Polymer

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“…Then the frozen specimens were broken by hammer impact and the fracture surface was observed using Laser scanning microscopy. The results (Figure 2-29 [87]) showed the brittle craze-crack initiation region with fine dimples, melt like stable crack growth region and brittle rapid crack growth region as well. What is more, except the defects and plane strain stress state in polymer, the intrinsic problem in polymer, free volume, can result in fracture as well.…”

Section: Fracture Of Polymersmentioning

confidence: 97%

“…Duan and Williams [81] conducted three point bending of a MDPE specimen with a machined notch in the middle of the specimen at the side of tension and found that a brittle craze-crack initiation region with fine dimples (broken voids or cavities in craze matter) and fibrils is formed behind the notch tip following with a melt like stable crack growth region with limited ductility and a final brittle rapid crack growth region (Figure 2-28). Marlus et al [87] carried out full notch creep test (FNCT) of HDPE and some of the specimens were moved out during the test and being frozen by liquid nitrogen. Then the frozen specimens were broken by hammer impact and the fracture surface was observed using Laser scanning microscopy.…”

Section: Fracture Of Polymersmentioning

confidence: 99%

Effect of insufficient homogenization during the extrusion of polyethylene pipes on butt fusion joint integrity

Troughton²,

Khamsehnezhad³

et al. 2020

Weld World

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High-density polyethylene (HDPE) is increasingly used for pipe applications owing to its lower cost and higher resistance to chemical corrosion and biological attack compared with metallic materials. Hence, HDPE with improved mechanical properties for pipe application were developed. In addition, additives are used to improve the longterm performance of PE pipes. Carbon black (CB) is one of the most widely used additives in PE pipes due to its low cost and absorption of UV which contributes to the resistance to photo degradation. However, it is difficult to achieve good homogenisation of HDPE and additives by the single-screw extrusion method. Insufficient homogenisation is observed as black (where HDPE and CB are well mixed) with white striations (only HDPE without CB); the white striations are called "windows". It has been shown that windows could lead to reduction of HDPE pipe performance and several methods have been developed to detect them. However, there is lack of study on the effect of windows on the integrity of butt fusion joints and there is only one method reported in open literatures which can quantify the window. However, this method causes material wastage.

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“…In this last case, the migration to the interface occurred via initial defects, and blisters were only observed within the migration zone (i.e., close to the initial defects). Schilling et al 21 compared different estimations of the crack propagation rate of a high-density polyethylene (PE-HD) resin using the Full Notch Creep Test (FNCT), destructive optical and laser scanning microscopy, and nondestructive SAM and Xray microcomputed tomography. The latter techniques were effective in monitoring the crack length, whereas laser scanning microscopy provided a detailed fracture morphology.…”

Section: Introductionmentioning

confidence: 99%

Detection and Quantification of Premature Crack Formation in Curing Epoxy Coatings

Weinell

Kiil

2022

Ind. Eng. Chem. Res.

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Cracks and defects, as a result of internal stress during curing, can accelerate the degradation and failure of protective epoxy coatings for essential infrastructures. To reduce, or eliminate, this so-called premature crack formation, it is essential to understand the underlying mechanisms. The present work investigated the simultaneous development in internal stresses, the degree of conversion of reactants (i.e., cross-linking), the volumetric shrinkage, and the elastic modulus of a solvent-based novolac epoxy cured with a cycloaliphatic amine. In addition, the crack susceptibility of the coating was quantified from a stress–strain curve (tensile mode), and the effects of film thickness, solvent content, pigment volume concentration, and flat versus 90-degree angle geometry were mapped. Finally, digital microscopy, in combination with a nondestructive scanning acoustic microscope (SAM) analysis, proved efficient for characterization of the crack morphology. Residual solvent, due to plasticization, promotes a low crack susceptibility. Later in the process, however, the solvent plasticization contributes to a high reactant conversion, and when the solvent finally evaporates, an increased internal stress is established. This, in turn, leads to an associated higher probability for crack initiation and growth. The crack susceptibility method provides insight and input to guidelines on how to modify formulations and curing conditions.

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Crack propagation in PE-HD induced by environmental stress cracking (ESC) analyzed by several imaging techniques

Cited by 17 publications

References 19 publications

Studying the mechanism of biodiesel acting as an environmental stress cracking agent with polyethylenes

Studying the mechanism of biodiesel acting as an environmental stress cracking agent with polyethylenes

Effect of insufficient homogenization during the extrusion of polyethylene pipes on butt fusion joint integrity

Detection and Quantification of Premature Crack Formation in Curing Epoxy Coatings

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