Gelation of a radiation crosslinked model polyethylene

Vallés, Enrique M.; Carella, José M.; Winter, H. Henning; Baumgaertel, M.

doi:10.1007/bf01329300

Cited by 54 publications

(29 citation statements)

References 18 publications

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“…Close to the gel dose, at 42 kGy, the slopes of G ′ and G ″ remained similar for the entire frequency range analyzed, with G ′ higher than G ″. This kind of behavior was entirely similar to some of our previous results on irradiated model polyethylene‐butene copolymers obtained by hydrogenation of anionically polymerized butadiene 17. Similar results were found for the changes on the viscoelastic properties of PE, PEH 3, and PEH 16 with increasing doses of radiation.…”

Section: Resultssupporting

confidence: 88%

Gamma‐irradiated metallocenic polyethylene and ethylene‐1‐hexene copolymers

Satti

Andreucetti

Quijada

et al. 2010

J of Applied Polymer Sci

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The aim of this work is to present a detailed study of the changes introduced by gamma radiation on several metallocenic polyethylene copolymers. Therefore, metallocenic polyethylene and copolymers with 3.3, 9.2, and 16.1 mol % of hexene comonomer content were synthesized and irradiated with 60 Co gamma radiation under vacuum at room temperature with radiation doses ranging from 0 to 100 kGy. Size Exclusion Chromatography data show that crosslinking reactions predominate over scission, even for the copolymer with the highest tertiary carbon content. Over a certain critical dose, which depends on the molecular weight and molecular structure of the initial polymer, an insoluble gel forms. The irradiated polymers also exhibit complex rheological behavior with increasing melt viscosity and elasticity, consistent with long chain branching and/or crosslinking. FTIR confirms depletion of terminal vinyl groups and increase of trans unsaturations with dose. The rate at which these two reactions evolve seems to depend on the comonomer content of the irradiated copolymers. Differential scanning calorimetry and Raman spectroscopy analyzes indicate less crystallinity and thicker interphases in irradiated materials. A mathematical model, which accounts for scission and crosslinking reactions, fitted well the evolution with radiation dose of the measured molecular weight data.

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Section: Resultssupporting

confidence: 88%

Gamma‐irradiated metallocenic polyethylene and ethylene‐1‐hexene copolymers

Satti

Andreucetti

Quijada

et al. 2010

J of Applied Polymer Sci

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show abstract

“…After the addition of the modifier, the curves shift toward low loss tangent indicating the increase in the melt elasticity. In the case of ADR‐modified PET, it is special that the loss tangents show a low dependence of the frequencies, which is the typical characteristics of the crosslinked polymer, and the degree of crosslinking increases with decreasing loss tangent . PET‐P4 with a high degree of branching also exhibits gel‐like behavior.…”

Section: Resultsmentioning

confidence: 99%

High‐melt‐elasticity poly(ethylene terephthalate) produced by reactive extrusion with a multi‐functional epoxide for foaming

Yang

Xin

Mughal

et al. 2017

J of Applied Polymer Sci

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A multi‐functional epoxide oligomer, Joncryl ADR‐4368 (ADR), is used as a modifier to prepare foamable poly(ethylene terephthalate) (PET) by reactive extrusion and compared with common tetra‐functional modifier pyromellitic anhydride (PMDA) as a reference. Torque evolution reveals that ADR has a faster reaction with PET than PMDA. The reactions generate long‐chain branches and gel structures, which are confirmed by rheological methods. Shear rheological studies show that PET modified with both ADR and PMDA display higher complex viscosity and lower loss tangent than unmodified sample. In particular, at a given viscosity level, ADR leads to a lower loss tangent than PMDA. Moreover, compared to PMDA, the addition of ADR results in a higher die pressure during extrusion and a more pronounced strain hardening during uniaxial elongation. These results indicate that ADR‐modified PET is less viscous but more elastic than PMDA‐modified PET. Owing to the higher elastic properties, ADR‐modified PET presents better foaming performance in batch foaming process with CO2 as a blowing agent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45805.

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“…Also, the loss tangent of XHDPE and decrosslinked XHDPE exhibits weak frequency dependence. Such dynamic rheological behavior is similar to a typical behavior of so-called "critical gel" [21][22][23][24][25][26][27] and "post critical gel" 21,28 within the frequency range below the rubbery plateau. The storage modulus of XHDPE and decrosslinked XHDPE is below the plateau modulus of HDPE.…”

Section: Dynamic Propertiesmentioning

confidence: 72%

Ultrasonic decrosslinking of crosslinked high-density polyethylene: effect of degree of crosslinking

Huang

Isayev

2014

RSC Adv.

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Decrosslinking of peroxide crosslinked high-density polyethylene (XHDPE) of different degrees of crosslinking by means of an ultrasonic single-screw extruder (SSE) is investigated. Barrel pressure and ultrasonic power consumption during extrusion are recorded. Swelling tests, rheological tests, infrared spectroscopy, thermal analysis and tensile tests are used to elucidate the structure-property relationship of decrosslinked XHDPE. It was found that a more intensive rupture of the crosslinked network occurs in XHDPE of a higher degree of crosslinking. Analysis based on the Horikx function shows that the type of preferential bond breakage during decrosslinking of XHDPE of various degrees of crosslinking is not determined by the bond energy alone but is also influenced by structural characteristics of the network.The activation energy of viscous flow of sols extracted from various decrosslinked XHDPEs supports the analysis based on the Horikx function. The dynamic, thermal and tensile properties of the decrosslinked XHDPE are greatly affected by the type of preferential bond breakage. A significant improvement in the processability and mechanical properties of decrosslinked 2% peroxide cured XHDPE is achieved due to the occurrence of a highly preferential breakage of crosslinks during ultrasonic decrosslinking.

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Gelation of a radiation crosslinked model polyethylene

Cited by 54 publications

References 18 publications

Gamma‐irradiated metallocenic polyethylene and ethylene‐1‐hexene copolymers

Gamma‐irradiated metallocenic polyethylene and ethylene‐1‐hexene copolymers

High‐melt‐elasticity poly(ethylene terephthalate) produced by reactive extrusion with a multi‐functional epoxide for foaming

Ultrasonic decrosslinking of crosslinked high-density polyethylene: effect of degree of crosslinking

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