Thermal degradation of polyethylene in a nitrogen atmosphere of low oxygen content

Holmström, Arne; Sörvik, Erling M.

doi:10.1016/s0021-9673(00)86708-4

Cited by 38 publications

(23 citation statements)

References 15 publications

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“…1). The heated tube was continuously purged by 20 mL/min of air. The air was passed through a trap containing activated charcoal to absorb any potential contaminants prior to entering the apparatus.…”

Section: Methodsmentioning

confidence: 99%

Identification of volatile compounds resulting from the thermal oxidation of polyethylene

Bravo

Hotchkiss

1993

J of Applied Polymer Sci

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SYNOPSISThe migration of compounds from polymer-based packaging may impart undesirable odors t o foods. We, therefore, undertook a study of the volatile compounds produced during the heating of polyethylene (PE) in the presence of excess O2 at temperatures of 150-350°C and for heating times of 5-15 min. Eighty-four volatile compounds in the range of C6-CZ3 were identified by gas chromatography mass spectrometry. The major products were aliphatic hydrocarbons, aldehydes, ketones, and olefins. Changes in temperature and heating times affected the amount and type of compounds produced, with hexanal being found in the largest amount and 300°C resulting in the greatest quantity of volatile compounds. At 350"C, greater amounts and numbers of low-boiling and fewer high-boiling compounds were formed. Only small amounts of volatiles were produced at 150°C. Many of the compounds identified have been reported to have odor and/or toxicological significance. 0 1993

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Section: Methodsmentioning

confidence: 99%

Identification of volatile compounds resulting from the thermal oxidation of polyethylene

Bravo

Hotchkiss

1993

J of Applied Polymer Sci

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“…Another parameter that plays a role is the amount of oxygen available [101]. An increase of the amount of oxygen will result in the formation of hydroperoxides that lead to an increase of the amount of radicals as shown in Scheme 1.…”

Section: -Degradation During Processingmentioning

confidence: 99%

“…Peroxide concentrations as calculated according to the above-mentioned equations (lines) and determined by an iodometric method (points) during a peroxide decomposition experiment at 70 °C with polypropylene pre-oxidized for several times at 70°C [108] Reprinted from Polymer Degradation and Stability, Vol 51, P. Gijsman, J. Hennekens and J. Vincent, The mechanism of the low-temperature oxidation of polypropylene, [95][96][97][98][99][100][101][102][103][104][105]1993, , with permission from Elsevier This decay could not be described with first or second order decomposition kinetics. Assuming that the titrated concentration of peroxides consists of two fractions (both decomposing according to first order kinetics), the calculated data could be fitted with the experimental values (see Fig.…”

Section: Fig 12mentioning

confidence: 99%

“…Also shown are the measured peroxide concentration (∆) and the calculated concentration of rapidly decomposing peroxides (+) after the above mentioned decomposition times. Reprinted from Polymer Degradation and Stability, Vol 51, P. Gijsman, J. Hennekens and J. Vincent, The mechanism of the low-temperature oxidation of polypropylene, [95][96][97][98][99][100][101][102][103][104][105]1993, with permission from Elsevier.…”

Section: Fig 12mentioning

confidence: 99%

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Review on the thermo-oxidative degradation of polymers during processing and in service

Gijsman

2008

E-Polymers

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“…The calibration curve for linear PE was obtained via the universal calibration curve as described earlier. 3 …”

Section: Gel Chromatographymentioning

confidence: 99%

Thermal degradation of polyethylene in a nitrogen atmosphere of low oxygen content. III. Structural changes occurring in low‐density polyethylene at oxygen contents below 1.2%

Holmström

Sörvik

1974

J of Applied Polymer Sci

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SynopsisSamples of low-density polyethylene, free from additives, were kept at temperatures between 284" and 3.55OC under nitrogen containing 1.16% oxygen or less. Changes in molecular weight distribution (MWD) and degree of long-chain branching (LCB) were followed by gel chromatography (GPC) and viscosity measurements. Other structural changes were investigated by infrared spectroscopy and differential scanning calorimetry (DSC ). Both chain scission and molecular enlargement occur simultaneously. Chain scission accounts for the formation of low molecular weight material and volatiles. Molecular enlargement reactions cause an increase in LCB and ultimately the formation of insoluble material. At lower temperatures (284'C) an increase in the high molecular weight end of the MWD is observed. The amount of olefinic unsaturation, carbonyl, and ether groups increase with degradation. Conju-* I n its original printing, this paper was unfortunately not in correct sequence. 3153It is being republished here in its entirety. JOURNAL OF APPLIED POLYMER SCIENCE VOL. 18 (1974)gated systems are formed. The formation of thin discolored and insoluble surface layers indicate that the attack of oxygen is diffusion controlled. The DSC thermograms undergo large changes a t 333" and 355"C, increasing with time and oxygen content. A reaction scheme for the thermc-oxidative degradation of polyethylene is discussed. Both inter-and intramolecular hydrogen abstractions by peroxy radicals are suggested to occur. Thus, the formation of trans-vinylene and ether groups results from intramolecular abstraction, while internal carbonyl groups are formed by intermolecular abstraction. Chain scission will be accomplished by both routes and together with "back-biting" is suggested to account, for the formation of volatiles. The formation of conjugated sequences causing discoloration is correlated with the formation of trans-vinylene groups. Because of the restricted accessability of oxygen under our conditions, the reactions discussed previously for pure thermal degradation' are also considered to be important. The molecular'enlargement observed is thus proposed to be mainly due to the combination of alkyl radicals even when oxygen is present,.

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Thermal degradation of polyethylene in a nitrogen atmosphere of low oxygen content

Cited by 38 publications

References 15 publications

Identification of volatile compounds resulting from the thermal oxidation of polyethylene

Identification of volatile compounds resulting from the thermal oxidation of polyethylene

Review on the thermo-oxidative degradation of polymers during processing and in service

Thermal degradation of polyethylene in a nitrogen atmosphere of low oxygen content. III. Structural changes occurring in low‐density polyethylene at oxygen contents below 1.2%

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