Pyrolytisch-gaschromatographische Untersuchungen an Polymeren

Noffz, D.; Pfab, W.

doi:10.1007/bf00509106

Cited by 28 publications

(9 citation statements)

References 1 publication

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“…In the “high- T regime” (≥500 °C), very high nominal heat-up rates are typically used to achieve x = 1 as rapidly as possible (“flash pyrolyses”) and allow direct interfacing with analytical apparatus. Configurations feature small samples with resistively heated filaments or ribbons or inductively coupled Curie-point heaters. − Because of heat transfer limitations and the endothermic nature of pyrolysis reactions, 1c,g, it appears prudent to consider quoted T 's as upper limits.…”

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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“…induction field of 1170 Oe seems to be ideal (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) ). We have shown earlier (6,7) that a fast and reproducible warm-up of samples in contact with cylindric ferromagnetic conductors can be obtained by high frequency induction heating.…”

Section: Tc [•C] Temperaturementioning

confidence: 99%

Curie Point Pyrolysis Gas Chromatography

Bühler¹,

Simon

1970

Journal of Chromatographic Science

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In Curie Point pyrolysis gas chromatography a ferromagnetic conductor in contact with the sample is heated inside a low volume glass capillary which is inserted into an rf coil with the carrier gas flowing through the capillary. The intrinsic properties of the conductor permit a self-control of the temperature to the Curie Point. The optimum wire diameter for a rapid warm-up is a function of the rf frequency. In order to have a fast temperature drop after cutting the rf field, small wire diameters are preferable. For such conductors relatively high frequencies are inherently necessary for a fast stabilization to the Curie Point. So far no differences in the self-controlled end-temperatures have been detected for wires of different origin.

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“…In the case of vinyl acetate (VAc), such studies extended to the copolymers with methacrylic, acrylic and maleic esters [2], ethylene [3,4], vinyl chloride [5,6], butyl acrylate or dibutyl maleate [7] and acrylonitrile [7].…”

mentioning

confidence: 99%