Diffusion mechanism of byproducts resulting from the peroxide crosslinking of polyethylene

Sahyoun, Jihane; Crépet, Agnès; Gouanvé, Fabrice; Keromnes, L.; Espuche, Éliane

doi:10.1002/app.44525

Cited by 33 publications

(29 citation statements)

References 34 publications

(39 reference statements)

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“…However, radical crosslinking with DCP gives rise to unwanted, volatile by‐products such as water, methane, acetophenone, cumyl alcohol and α ‐methylstyrene, which tend to increase the electrical conductivity . The removal of these by‐products – and hence recovery of a low conductivity – is achieved through degassing, an energy‐intensive process during which cables are heated for an extended period of time, e.g.…”

Section: Introductionmentioning

confidence: 99%

Click chemistry‐type crosslinking of a low‐conductivity polyethylene copolymer ternary blend for power cable insulation

Mauri

Hofmann

Gómez-Heincke

et al. 2020

Polymer International

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High‐voltage direct‐current power cables are vital for the efficient transport of electricity derived from renewable sources of energy. The most widely used material for high‐voltage power cable insulation – low‐density polyethylene (LDPE) – is usually crosslinked with peroxides, a process that releases unwanted by‐products. Hence, by‐product‐free crosslinking concepts that mitigate the associated increase in electrical conductivity are in high demand. Click chemistry‐type crosslinking of polyethylene copolymer mixtures that contain glycidyl methacrylate and acrylic acid co‐monomers is a promising alternative, provided that the curing reaction can be controlled. Here, we demonstrate that the rate of the curing reaction can be adjusted by tuning the number of epoxy and carboxyl groups. Both dilution of copolymer mixtures with neat LDPE and the selection of copolymers with a lower co‐monomer content have an equivalent effect on the curing speed. Ternary blends that contain 50 wt% of neat LDPE feature an extended extrusion window of up to 170 °C. Instead, at 200 °C rapid curing is possible, leading to thermosets with a low direct‐current electrical conductivity of about 10−16 S cm−1 at an electric field of 20 kV mm−1 and 70 °C. The conductivity of the blends explored here is comparable to or even lower than values measured for both ultraclean LDPE and a peroxide‐cured commercial crosslinked polyethylene grade. Hence, click chemistry curing represents a promising alternative to radical crosslinking with peroxides. © 2019 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Click chemistry‐type crosslinking of a low‐conductivity polyethylene copolymer ternary blend for power cable insulation

Mauri

Hofmann

Gómez-Heincke

et al. 2020

Polymer International

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“…The most widely used crosslinking process is based on peroxides and in particular dicumyl peroxide (DCP), [11][12][13] which produces volatile and hazardous byproducts such as water, methane, acetophenone, cumyl alcohol and a-methyl styrene. 14,15 These unwanted byproducts must be removed by means of a time and energy consuming degassing step. 16 Since even traces of the remaining impurities can increase the electrical conductivity of polyethylene, any reduction in the amount of peroxide tends to improve the overall quality of the insulation material.…”

Section: Introductionmentioning

confidence: 99%

Byproduct-free curing of a highly insulating polyethylene copolymer blend: an alternative to peroxide crosslinking

et al. 2018

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“…Since this average value is in the same order of magnitude, but between 2 and 5 times lower than that reported for PE [6], the presence of diffusion traps is suspected in the three EPDMs under study. According to the literature [4,5,15e17], two main trapping mechanisms can be considered: i) The establishment of intense interactions (hydrogen bonds) with polar groups coming from vulcanization additives (ZnO [11], stearic acid [12], a-cumyl alcohol originating from peroxide by-products [13,14], etc.) or formed during the processing operation (oxidation products); ii) The formation of water clusters in free volume holes.…”

Section: Definition Of Water Uptakementioning

confidence: 99%

“…On the one hand, it is well known that these elastomers are not totally pure but contain several vulcanization additives, some of them carrying polar groups able to establish intense interactions with water molecules (e.g. zinc oxide [11], stearic acid [12], or acumyl alcohol originating from peroxide by-products [13,14], etc.). What is the impact of EPDM formulation on water absorption?…”

Section: Introductionmentioning

confidence: 99%

Investigation and modelling of the water transport properties in unfilled EPDM elastomers

Lacuve

Colin

Perrin

et al. 2019

Polymer Degradation and Stability

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The water sorption properties (i.e. diffusivity and solubility) of three unfilled vulcanized EPDMs were investigated in wet atmosphere (typically between 0 and 95% RH) and in pure distilled water (denoted as 100% RH) at 70 C with an IGAsorp dynamic sorption analyzer. In the 0e0.5 activity range, all EPDMs obey to the usual Fick and Henry's laws. In contrast, at activities higher than 0.5, the water sorption behavior of all EPDMs deviates from these two laws because of the formation of water clusters. Park's equation was used for simulating accurately the sorption isotherms and thus, accessing Henry's constant and the average size of water clusters. In wet atmospheres, clusters would be composed of about 8 ± 4 molecules corresponding approximately to the size of free volume holes. In contrast, in pure distilled water, clusters consist in a much larger number of water molecules (between 55 and 71) presumably because of an exacerbated swelling of EPDM samples. Thus, immersion in water solution is more drastic than exposure to fully saturated wet atmosphere. The impact of the EPDM formulation (nature and content of crosslinking agent) on these experimental results is clearly of the second order of magnitude.

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Diffusion mechanism of byproducts resulting from the peroxide crosslinking of polyethylene

Abstract: International audienc

Cited by 33 publications

References 34 publications

Click chemistry‐type crosslinking of a low‐conductivity polyethylene copolymer ternary blend for power cable insulation

Click chemistry‐type crosslinking of a low‐conductivity polyethylene copolymer ternary blend for power cable insulation

Byproduct-free curing of a highly insulating polyethylene copolymer blend: an alternative to peroxide crosslinking

Investigation and modelling of the water transport properties in unfilled EPDM elastomers

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