Rates of molecular vaporization of linear alkanes

Wall, Leo A.; Flynn, Joseph H.; Straus, Sidney

doi:10.1021/j100711a015

Cited by 30 publications

(18 citation statements)

References 4 publications

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“…83 Because no single technique appears to have been able to provide calibrated quantitative N c distributions over the entire c range, there remains a critical need for such data as a function of conditions.…”

Section: Data Overviewmentioning

confidence: 99%

Reexamination of the Pyrolysis of Polyethylene: Data Needs, Free-Radical Mechanistic Considerations, and Thermochemical Kinetic Simulation of Initial Product-Forming Pathways

Poutsma

2003

Macromolecules

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Gaps in the voluminous data on pyrolysis of polyethylene that impede mechanistic understanding are highlighted, especially for H:C material balances, product distributions at varying conversions in isothermal closed systems, and inconsistencies between GC and FIMS analyses of products with lower volatility. Thermochemical kinetic estimates are made for the rates of various initiation processes; these suggest that molecular disproportionation contributes to chain initiation, along with homolysis, at lower Mn. Simulations indicate that the standard statistical test for random scission, a linear relationship between log Nc and c for volatile products, is not generally valid in open systems, and its empirical observation implies restrictions on the dependence of the rate of volatilization on c.Simulations of the initial distributions of volatile products and residue functionalities were performed based on propagation rate constants estimated by thermochemical kinetic procedures. The practice of deducing the amount of backbiting from positive deviations at lower c from the linear log N c-c relationship established for higher c values is shown to underestimate the fraction of backbiting because the latter will give some products at every c so long as the 1,5-shift is not exclusive (k15 . k16 > k14). Compositions of volatiles at finite conversions were simulated by formal superposition of (a) backbiting and unzipping products predicted from this kinetic model and (b) random scission products, which form only after multiple bond cleavages, predicted from a statistical model. Comparisons with experimental data showed some success but were limited by data gaps and inconsistencies.

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Section: Data Overviewmentioning

confidence: 99%

Reexamination of the Pyrolysis of Polyethylene: Data Needs, Free-Radical Mechanistic Considerations, and Thermochemical Kinetic Simulation of Initial Product-Forming Pathways

Poutsma

2003

Macromolecules

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“…Linear alkanes as large as C 94 have been observed to vaporize without decomposition. 7 Thermolysis coupled with reactive distillation can convert waste polyethylene into condensable liquid products with high yields and suppress the production of the waxy fraction. The main products from thermolysis/reactive distillation are primarily ␣-olefins (43 mol %) and normal alkanes with an average chain length of approximately 14 carbons.…”

Section: Introductionmentioning

confidence: 99%

The effect of short-chain branching on the thermolysis/reactive distillation of polyethylene

McCaffrey

Cooper

Kamal

1999

J. Appl. Polym. Sci.

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Thermolysis, coupled with reactive distillation, was investigated as a process to convert waste olefin-based polymers into value-added products. The degradation of two types of polyethylene, linear low and high density, was investigated. The initial molecular structure of the polymer was found to have a large effect on the rate of molecular weight reduction. The linear low-density polyethylene started to produce volatile products earlier and at a faster rate than the high-density polyethylene. Preferential scission of the side branches from the linear low-density polymer backbone was shown to be one of the first steps of the degradation mechanism. Once the branches were stripped from the linear low-density polyethylene, the degradation products were similar to those produced from high-density polyethylene.

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“…22 The experimental procedure consisted of suspending a quartz bucket (4 ϫ 10 mm) containing a 10-mg sample by a 76.2-m tungsten wire hung from a weighing beam. All runs were reproducible to Ϯ1.0%.…”

Section: Rates Of Molecular Vaporizationmentioning

confidence: 99%

“…The molecular weight dependence of I c in equation (19) may be derived by solving equation (7) for N 2 and inserting the results into equations (19) and (20) to give (22) where (22), the heat of vaporization may be expressed as…”

Section: Heat Capacity Difference and Heat Of Vaporizationmentioning

confidence: 99%

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Enthalpies of vaporization of oligomers of poly(hexamethylene sebacate) and esters of alkylcarboxylic acids

Phillips

1998

J of Applied Polymer Sci

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Enthalpies of vaporization for esters covering a molecular weight range of about 74 -939 g/mol ⅐ [monocarboxylics; linear esters of sebacic series; branched esters of triglyceride series; and, oligomer esters of poly(hexamethylene sebacate)] and a temperature range of about 273.15-523.15 K have been empirically fitted to within about 5% to an equation of the following form:is the molecular weight (molar mass); T is in degrees Kelvin; and, C, K 0 , a, b 0 , and a 0 are constants. These results were used to determine the heat capacity difference,

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Rates of molecular vaporization of linear alkanes

Cited by 30 publications

References 4 publications

Reexamination of the Pyrolysis of Polyethylene: Data Needs, Free-Radical Mechanistic Considerations, and Thermochemical Kinetic Simulation of Initial Product-Forming Pathways

Reexamination of the Pyrolysis of Polyethylene: Data Needs, Free-Radical Mechanistic Considerations, and Thermochemical Kinetic Simulation of Initial Product-Forming Pathways

The effect of short-chain branching on the thermolysis/reactive distillation of polyethylene

Enthalpies of vaporization of oligomers of poly(hexamethylene sebacate) and esters of alkylcarboxylic acids

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