Influence of the molecular structure on slow crack growth resistance and impact fracture toughness in Cr‐catalyzed ethylene‐hexene copolymers for pipe applications

Stephenne, Vincent; Daoust, Daniel; Debras, G.; Dupire, M.; Legras, Roger; Michel, J. P.

doi:10.1002/app.1923

Cited by 19 publications

(9 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The molecular structure is undoubtedly the most critical factor, being the object of many publications [27][28][29][30][31]. The molecular structure together with the processing conditions will determine the morphological structure of the polymer, crystallinity and lamellar thickness being critical aspects to bear in mind [32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene‐hexene copolymers for pipe applications

García

Carrero

Aroca

et al. 2008

Polymer Engineering & Sci

View full text Add to dashboard Cite

A bimodal system has been developed by blending a high density and linear medium density ethylene‐hexene copolymers synthesized with chromium and metallocene catalysts, respectively. The resistance to slow crack growth examined by the Pennsylvania Edge‐Notch Tensile test (PENT test‐ASTM F1473) and the crack opening displacement was determined at 80°C and 2.4 MPa. The effects of molecular and morphological structure on the slow crack growth (SCG) resistance were evaluated, the molecular weight and lamellar thickness being the most critical parameters for this system. The great importance of the short chain branching content and distribution was determined and discussed by SEC‐FTIR. Therefore, two main factors were found determinant in the SCG resistance. On the one hand, the increase of tie molecule density and therefore the continuity in the network formed by crystals and tie molecules and, on the other hand, the short chain branching density increase as the linear medium density ethylene‐hexene copolymer fraction does so. In addition, a morphological analysis of the fracture surface was performed in order to analyze the fracture mechanisms that took place. Differences observed in the fracture surface morphology were related to the molecular and morphological structure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

show abstract

Section: Introductionmentioning

confidence: 99%

Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene‐hexene copolymers for pipe applications

García

Carrero

Aroca

et al. 2008

Polymer Engineering & Sci

View full text Add to dashboard Cite

show abstract

“…Resin development has seen both high molecular weight and medium molecular weight PE be used with single and bimodal molecular weight distribution. Early generation pipes did not contain carbon black additives, while modern day resins do . Regardless of the resin type, all PE pipes and plastic products in general contain an antioxidant package.…”

Section: Introductionmentioning

confidence: 94%

Linking Antioxidant Depletion with Material Properties for Polyethylene Pipes Resins

Byrne

Silva

Hilditch

2019

Polymer Engineering & Sci

View full text Add to dashboard Cite

Plastic pipes used in gas distribution networks are typically made from polyethylene (PE) and are stabilized against degradation by antioxidants. Over time, the antioxidant is consumed and the polymer integrity can become compromised. The rate of antioxidant depletion can be dependent on the specific grade of PE and the surrounding environment. In this research, the crystallinity, tensile strength, Young's modulus, and strain at break were measured for the four most commonly used PE pipe resins in the Australian natural gas distribution network as a function of antioxidant content. A relationship between the changes in material properties with antioxidant consumption was established. By measuring the carbonyl index (CI), which quantifies the amount of degradation products present, and linking this with the oxygen induction time (OIT), it was found that three clear regions exist for all investigated PE resins. These distinct regions of the OIT-CI relationship correlate with regions of substantially different rate of change in material properties, and hence indicate a measure of the integrity of the PE. POLYM. ENG. SCI., 60:323-329, 2020.

show abstract

“…Deuterium o-dichlorobenzene (O-DCB) was used as a solvent at the test temperature of 120 C, and the PE sample concentration was about 15%. [25] Chemical shifts were referenced to the isolated methylene carbon of 30.0 and accumulated to 5000 times.…”

Section: Carbon Nuclear Magnetic Resonance Spectroscopy (C-nmr)mentioning

confidence: 99%

Research on slow crack growth resistance of polyethylene pipe based on strain hardening modulus

Zhang

Xiang

Lü

et al. 2021

Vinyl Additive Technology

View full text Add to dashboard Cite

Slow crack growth (SCG) is the principal factor for determining the operating lifetime of polyethylene (PE) pipes. Exploring the relationship between the molecular structure and the strain hardening (SH) modulus is helpful to evaluate the SCG resistance of PE pipe materials accurately. This paper uses an efficient SH test method to study the SH modulus for four kinds of PE pipes. Meanwhile, the correlation between SH modulus and sample thickness, material crystallinity (X c ), comonomer type and content, weight-average molecular weight, and molecular weight distribution has been established and investigated respectively. The results represent that the comonomer type and the X c of PE materials played significant roles in the SH modulus. The SH modulus of ethylene-hexene copolymer is 5-7 MPa higher than that of ethylene-butene copolymer. The amount in the range of 1 Â 10 3 to 1 Â 10 5 of the molecular weight distribution of PE materials has a significant contribution to the establishment of the tie molecular network. In addition, the higher X c and the thinner thickness were beneficial to obtain the higher measured SH modulus.

show abstract

Influence of the molecular structure on slow crack growth resistance and impact fracture toughness in Cr‐catalyzed ethylene‐hexene copolymers for pipe applications

Cited by 19 publications

References 42 publications

Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene‐hexene copolymers for pipe applications

Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene‐hexene copolymers for pipe applications

Linking Antioxidant Depletion with Material Properties for Polyethylene Pipes Resins

Research on slow crack growth resistance of polyethylene pipe based on strain hardening modulus

Contact Info

Product

Resources

About