Pyrolysis-hydrogenation-GLC of alpha olefin copolymers

Schooten, J. van; Evenhuis, J.K

doi:10.1016/0032-3861(65)90052-2

Cited by 30 publications

(14 citation statements)

References 19 publications

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“…• C Caa (11) Following random scission and hydrogenation, a series of products would be formed of the type None of these series are present in the chromatograms. Thus there is a hierarchy of preferred modes of scission.…”

Section: Resultsmentioning

confidence: 99%

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Investigation of short-chain branches in polyethylene by pyrolysis - GCMS

Haney¹,

Johnston²,

Clampitt³

1983

Macromolecules

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A novel pyrolysis-hydrogenation-GCMS technique has been developed and applied to branched polyethylenes of both the high-pressure and low-pressure varieties. The unique features of the technique are pyrolysis at low temperatures (360 °C) and low extent of pyrolysis of the sample (approximately 2% volatilized). This yields a high percentage of pyrolysis products pertaining to the branch points. Study of model ethylene-a-olefin copolymers shows that the pyrolysis products from branch points can be predicted solely by consideration of the possible carbon-carbon scissions a and ß to the branch points. The variety of products from high-pressure polyethylene, however, is greater than that expected simply from the branch-formation mechanism proposed by Roedel and Willbourn. An expanded polymerization scheme has been formulated that includes the occurrence of intramolecular 1,3 hydrogen transfers as well as intramolecular 1,5 hydrogen transfers in the formation of short-chain branches.

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Section: Resultsmentioning

confidence: 99%

“…Various instrumental techniques have been used to determine the type and number of short branches. These include (a) infrared spectroscopy,1 (b) carbon-13 NMR,2-7 (c) radiolysis-GC,8-10 (d) pyrolysis-GC, [11][12][13][14][15][16] and (e) pyrolysis-GCMS.17 These techniques have shown the presence of ethyl and n-butyl.…”

Section: Introductionmentioning

confidence: 99%

Investigation of short-chain branches in polyethylene by pyrolysis - GCMS

Haney¹,

Johnston²,

Clampitt³

1983

Macromolecules

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“…The peracids formed in the polymer melt would most probably decompose, according to reaction (22). The peracids formed in the gas phase can oxidize ketones to esters, leaving acids, or can oxidize aldehydes to acids.…”

Section: \Ch/chzmentioning

confidence: 99%

Thermo‐oxidative degradation of low‐density polyethylene close to industrial processing conditions

Hoff

Jacobsson

1981

J of Applied Polymer Sci

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SynopsisThermo-oxidative degradation of low density polyetylene (LDPE) at a low degree of volatilization (about 4%) at 266289°C was studied. Gas chromatography-mass spectrometric analysis was used to separate and identify the products of LDPE decomposition. Altogether 44 compounds representing hydrocarbons, alcohols, aldehydes, ketones, acids, cyclic ethers, cyclic esters, and hydroxycarhoxylic acids were identified. Sixteen oxygen-containing products were quantified. Among the components identified, the fatty acids and aldehydes predominated. The most abundant.product was formic acid. The mechanism of formation of the degradation products is discussed.

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“…Grassie15 and Mayo16' both consider formation of internal carbony1 groups to proceed according to reactions (17), (18), and (33) involving intermolecular hydrogen abstraction :…”

Section: Discolorationmentioning

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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Pyrolysis-hydrogenation-GLC of alpha olefin copolymers

Cited by 30 publications

References 19 publications

Investigation of short-chain branches in polyethylene by pyrolysis - GCMS

Investigation of short-chain branches in polyethylene by pyrolysis - GCMS

Thermo‐oxidative degradation of low‐density polyethylene close to industrial processing conditions

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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