Influences of unsaturation and metal impurities on the oxidative degradation of high density polyethylene

Chirinos-Padron, Alfonso; Hernández, Petra H.; Chávez, Emily; Allen, Norman S.; Vasiliou, Constantine; DePoortere, Michel

doi:10.1016/0014-3057(87)90036-x

Cited by 48 publications

(20 citation statements)

References 10 publications

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“…The unsaturated chain end group should be the initiator because the allyl radical to be produced has higher resonance stability. In fact, in the case of polyethylene, Allen and colleagues have already pointed out that the unsaturated group is the initiator [24,25]. The added MiPP would be expected to function as the degradation initiator.…”

Section: Resultsmentioning

confidence: 99%

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Nakatani

Kurniawan

Taniike

et al. 2008

Science and Technology of Advanced Materials

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In this work, the relationship between the unsaturated chain end group content and the thermal oxidative degradation rate was systematically studied with binary polymer blends of isotactic polypropylene (iPP) with and without the unsaturated chain end group. The iPPs with and without the unsaturated chain end group were synthesized by a metallocene catalyst in the absence of hydrogen and by a Ziegler catalyst in the presence of one, respectively. The thermal oxidative degradation rate of the binary iPP blends was estimated from the molecular weight and the apparent activation energy ( E), which were obtained through size exclusion chromatography (SEC) and thermogravimetric analysis (TGA) measurements, respectively. These values exhibited a negative correlation against the mole content of the unsaturated chain end group. The thermal oxidative degradation rate apparently depends on the content of the unsaturated chain end group. This tendency suggests that the unsaturated chain end acts as a radical initiator of the iPP degradation reaction.

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Section: Resultsmentioning

confidence: 99%

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Nakatani

Kurniawan

Taniike

et al. 2008

Science and Technology of Advanced Materials

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“…The interaction was confirmed by DSC measurements as well [23], but needs further attention in the future. Changes in viscosity and processability are attributed to the formation of LCBs going through the chain-end vinyl groups of the polymer [32,33]. The effect of additive content and processing history (No.…”

Section: Processing Stabilizationmentioning

confidence: 99%

Melt stabilization of polyethylene with dihydromyricetin, a natural antioxidant

Kirschweng

Bencze

Sárközi

et al. 2016

Polymer Degradation and Stability

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Experiments have been carried out to compare the stabilization effect of two flavonoid type natural antioxidants, dihydromyricetin (DHM) and quercetin (Q) in polyethylene (PE). Additive concentrations changed between 0 and 500 ppm in several steps and 1000 ppm Sandostab PEPQ phosphorus containing secondary stabilizer was also added to each compound. Both antioxidants are very efficient stabilizers for PE, sufficient melt stability was achieved already at 50 ppm DHM content. At small concentrations dihydromyricetin proved to be more efficient melt stabilizer and it protected the secondary antioxidant better than quercetin. In spite of its better efficiency in melt stabilization, polymers containing DHM had the same residual stability as those prepared with quercetin. Accordingly, the larger efficiency does not result from the larger number of active phenolic hydroxyls in the molecule, but from interactions with the phosphorous secondary stabilizer that is stronger or at least different for DHM than quercetin. In spite that DHM is a white powder, it gave the polymer a brownish color which became deeper with increasing number of extrusions and additive content. Nevertheless, both natural antioxidants can be used efficiently for the stabilization of polymers in applications in which color is of secondary importance.

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“…Transition metals such as Fe, Zn and Cu were reported to increase the degradation rate of either polymers or long molecular chain organic compounds [22-24, 27, 36, 37]. Copper used as central conductor material can produce significant catalytic effect on polymer oxidation during the thermal stress [3,[21][22][23] by hydroperoxides scissions into free radicals [24,25]:…”

Section: Introductionmentioning

confidence: 99%

Copper diffusion in cable-insulating materials by chemiluminescence and DSC techniques

Jipa

Setnescu

Zaharescu³

et al. 2015

J Therm Anal Calorim

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Chemiluminescence (CL) and differential scanning calorimetry (DSC) were applied for proving the copper ion migration processes occurring within the lowdensity polyethylene (LDPE) electrical insulator as a consequence of intimate contact. Thin LDPE slides of 0.5 mm thick were subjected to short-time thermal stress at temperatures between 80 and 120°C. Both CL and DSC kinetic parameters revealed the acceleration of posttreatment oxidation at elevated temperatures (170-200°C) in copper-contacting polymer as in respect to the cases when Cu was absent. It was revealed that the oxidation rate measured by CL was more than two times higher for the samples heated in the presence of Cu than in its absence, while the oxidation induction time from DSC was considerably lowered for the same samples. Elemental analysis data provided by atomic absorption spectroscopy and particle-induced X-ray emission techniques as well as SEM investigations confirmed the presence of copper within the samples subjected to thermal treatment when the polymer insulation was in contact with the metallic conductor. Chemiluminescence procedure has a remarkable sensitivity to detect the effect of copper in the polymer matrix even at low concentrations.

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Influences of unsaturation and metal impurities on the oxidative degradation of high density polyethylene

Cited by 48 publications

References 10 publications

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Melt stabilization of polyethylene with dihydromyricetin, a natural antioxidant

Copper diffusion in cable-insulating materials by chemiluminescence and DSC techniques

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