Fracture characterization of low-density polyethylenes by the essential work of fracture: Changes induced by thermal treatments and testing temperature

Casellas, J. J.; Frontini, Patricia María; Carella, José M.

doi:10.1002/(sici)1097-4628(19991024)74:4<781::aid-app4>3.0.co;2-r

Cited by 30 publications

(18 citation statements)

References 23 publications

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“…A linear correlation is evidenced, as theoretically expected. Casellas et al 21 studied a similar LDPE in similar conditions. Williams and Rink proposed that this value should be above 0.98 for EWF analysis.…”

Section: Optical Stress Coefficientmentioning

confidence: 99%

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Determination of the fracture energy in polymeric films by in situ photoelasticimetry on double edge notch specimen

Dubelley

Planès

Bas

et al. 2015

J of Applied Polymer Sci

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The fracture toughness is key parameters to select polymeric films. The essential work of fracture (EWF) is a phenomenological but efficient way to characterize this resistance to fracture. One can gain valuable information on the resistance to perforation and propagation of flaws. A new technique was developed to better understanding the EWF experiments. A tensile test combined to photoelasticimetry allows following in situ the geometry and amount of plastic deformation on double edge notched specimen. The EWF parameters are determined when the plastic deformation appears constant, so when the fracture energy W f only contributes to rupture filament. This new methodology requires just a single sample, whereas at least five specimens are required for general method. It will help characterize expensive polymeric films or reveal the heterogeneous behavior, for instance after polymer ageing.

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Section: Optical Stress Coefficientmentioning

confidence: 99%

“…The Polyethylene (PE) seems to be a good candidate and has already been the subject of many studies. 2,4,[14][15][16][17][18][19][20][21]…”

Section: Introductionmentioning

confidence: 99%

Determination of the fracture energy in polymeric films by in situ photoelasticimetry on double edge notch specimen

Dubelley

Planès

Bas

et al. 2015

J of Applied Polymer Sci

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“…Other researchers also found differences in the modulus with similar crystallinity after different thermal treatments, and this has been shown to be attributed to the difference of intercrystalline structural continuity. [41] Slow crystallisation is in favour of liquid-liquid phase separation for the most highly branched polymer fractions. [42] As mentioned above, the oven slowly cooled blends with 20-50% C 8 VLDPE show two well-defined melting peaks, indicating that partial segregation of the fractions with different sequence lengths have formed two morphologies.…”

Section: Relationship Between Structure and Mechanical Propertiesmentioning

confidence: 99%

“…This phase separation gives rise to a better mechanical interconnection of the crystalline lamellae. [41] If the branch concentration of two copolymers is not very different, noncrystalline regions are expected to be miscible. The miscibility of non-crystalline regions produces a synergistic effect on the tensile strength.…”

Section: Relationship Between Structure and Mechanical Propertiesmentioning

confidence: 99%

Structural and Mechanical Properties Changes of Ethylene‐α‐olefin Copolymer Blends Induced by Thermal Treatments and Composition

Chen

Shanks

Amarasinghe

2004

Macro Materials & Eng

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Summary: Blends of single‐site catalysed ethylene‐α‐butene (C4VLDPE) and ethylene‐α‐octene (C8VLDPE) copolymers were prepared by melt extrusion. The phase morphology, thermal and mechanical properties of the blends have been investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile test and dynamic mechanical analysis (DMA). Depending on the composition and thermal history, significant differences in structure and behaviour were found. It was also found that some degree of co‐crystallization occurred for quenched blends; whereas most of the oven slowly cooled blends showed two well‐defined melting peaks, indicating that the slow cooling favoured partial segregation of the fractions with different degrees of branching to form two morphologies. Moreover, SEM revealed morphology of the thinner crystals distributed in‐between the thicker sheaf‐like crystals for the slowly cooled blends with 20–50% C8VLDPE. Therefore, the synergism in mechanical properties for the blends with 20–50% C8VLDPE is due to a combination of larger crystal size, more complete phase separation and interfacial interaction produced by the segregation effect of the slow cooling treatment. DMA studies showed that the storage modulus increased as the addition of C8VLDPE and modulus for the slowly cooled blends are about twice those measured for the quenched ones, indicating higher stiffness of the blends. The smooth shift of β relaxation temperature with addition of C8VLDPE for both sets of blends confirmed the miscibility in the amorphous phase.SEM image of the C4VLDPE‐C8VLDPE (50/50) blend after oven slow cooling treatment.magnified imageSEM image of the C4VLDPE‐C8VLDPE (50/50) blend after oven slow cooling treatment.

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“…This method was developed by Broberg 11,12 for metals and was later used for polymers by Mai and Cotterell,13,14 and it has been widely used for more than a quarter of a century to assess fracture properties in thin polymer plates under plane stress conditions by testing deeply double edge notched tensile specimens (DDEN-T). [15][16][17][18][19] This method assumes that the energy consumed in the ductile tearing failure could be divided into two terms. One of them corresponds to the energy needed to create the new fracture surfaces and is called essential work (W e ), which is related to the inner fracture process zone (IFPZ) ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Analysis of the effect of the test rate on polymer essential work of fracture parameters for the small punch test

Cuesta¹,

Alegre²

2016

J of Applied Polymer Sci

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In recent decades, one of the non-standard tests that has been consolidated as a viable alternative in those cases where there is not sufficient material to carry out standard tests is the small punch test. This test basically consists of deforming a miniature specimen using a high strength punch. It is possible for this miniature specimen to have an initial pre-notch with the aim of improving the fracture behavior estimation of the material analyzed. Recently, to characterize the fracture properties of polymer sheets under plane stress conditions, there has been an attempt to establish the feasibility of applying the essential work of fracture (EWF) method in polymer pre-notched miniature specimens. This article intends to go one step beyond and focuses on the test rate, which is an important aspect in the EWF application. Its effect on the EWF parameters in polymer pre-notched miniature specimens has been analyzed and its correlation has been established with the results obtained from standard specimens. V C 2016 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2016, 133, 43314.

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Fracture characterization of low-density polyethylenes by the essential work of fracture: Changes induced by thermal treatments and testing temperature

Cited by 30 publications

References 23 publications

Determination of the fracture energy in polymeric films by in situ photoelasticimetry on double edge notch specimen

Determination of the fracture energy in polymeric films by in situ photoelasticimetry on double edge notch specimen

Structural and Mechanical Properties Changes of Ethylene‐α‐olefin Copolymer Blends Induced by Thermal Treatments and Composition

Analysis of the effect of the test rate on polymer essential work of fracture parameters for the small punch test

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