Modelling end-chain scission and recombination of linear polymers

Staggs, J.E.J.

doi:10.1016/j.polymdegradstab.2004.01.021

Cited by 28 publications

(35 citation statements)

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“…Solutions were obtained by transforming the PBE into its moment form. Staggs derived a similar discrete form and solved for special cases of random scission and large initial MW [56][57][58], for random scission and recombination [59], and for radical depropagation [60]. An even more detailed approach has considered the evolution of populations of alkane, alkene and dialkene species in the degradation of polyethylene and polypropylene [61].…”

Section: Overview Of Pyrolysis Modeling Effortsmentioning

confidence: 99%

“…One simple approach is to assume that all chains with MW less than some critical threshold, v c , are immediately volatized [57]. This is the model of volatilization that will be used throughout this section.…”

Section: B Random Scission Modelmentioning

confidence: 99%

“…where equation 16 is an improvement over past approaches in which mass loss was accounted for by simply truncating the number density function below some critical MW of volatilization, c v [57,69]. That is,…”

Section: E Submodelsmentioning

confidence: 99%

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Experimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket Motor Internal Insulation

Koo¹,

Ezekoye²

2009

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. (From -To) 1 J u n e . 2 0 0 6 -3 0 S e p t . 2 0 0 9 REPORT DATE (DD-MM-YYYY) 30-09-2009 REPORT TYPE Final Report DATES COVERED TITLE AND SUBTITLEExperimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBERThe University of Texas at Austin, Dept. of Mechanical Engineering, 1 University Station, C2200, Austin, TX 78712-0292 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Dr. Charles Y-C Lee AFOSR AFOSR/NL 875 N. Randolph St., Ste. 325 SPONSOR/MONITOR'S REPORTArlington, VA 22203 NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Research objective is to develop a modeling framework for simulating the insulative behavior of thermoplastic polyurethane elastomer nanocomposites (TPUNs) for solid rocket motors (SRMs). This research combines numerical modeling and experimental characterization of TPUNs for SRM insulation. Two families of TPUNs based on nanoclay, carbon nanofiber (CNF), and multiwall carbon nanotubes (MWNT) were developed. TGA experiments were conducted on Kevlar-EPDM, TPU, TPUN-clay, TPUN-CNF, and TPUN-MWNT in both air and nitrogen at low heating rates. Kinetics was calculated using isoconversion technique. High heating rate TGA was conducted on selective TPUNs. Flammability tests indicated TPUN-clay has the toughest char, followed by TPUN-MWNT, then TPUN-CNF. We connected the population balance framework to atomistic calculations to determine what aspects of the atomistic simulations would likely affect the meso-scale evolution. We focused on understanding the role that the scission kernel has on the overall degradation process and also on the role of the stoichiometry parameter has on the overall degradation kinetics. We began using the atomistic simulation code RXN MD to compute scission kinetics parameters. We recognized that the critical issue in characterizing a particular materials ablation rate could be captured by investigating the steady state ablation proc...

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Section: Overview Of Pyrolysis Modeling Effortsmentioning

confidence: 99%

Section: B Random Scission Modelmentioning

confidence: 99%

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Experimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket Motor Internal Insulation

Koo¹,

Ezekoye²

2009

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“…No distinction is made between molecules and radicals. This leads to a set of ordinary differential equations governing the evolution of the population [7][8][9]. However, there are mathematical advantages to considering the linear polymer molecule as a continuous length, which can then be infinitely subdivided.…”

Section: Population Balance Models Of Random Scission and Recombinationmentioning

confidence: 99%

“…In two recent papers [7,8], the author explored the possibility of using a different approach, based on discrete population balance equations, to model volatile production rate during thermal degradation involving random scission and endchain scission. Other authors have explored this type of approach in order to predict the evolution of a population of molecules undergoing different scission mechanisms [9][10][11][12], however the application to volatile production rate for pyrolysis modelling has not received a great deal of attention.…”

Section: Introductionmentioning

confidence: 99%

A continuous model for vapourisation of linear polymers by random scission and recombination

Staggs

2005

Fire Safety Journal

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Analytical and numerical simulations of depolymerization based on discrete model: A chain‐end scission scenario

Wang

Luo

et al. 2022

AIChE Journal

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Depolymerization by chain‐end scission enables ideally full recovery of monomers, which is considered as a promising route for polymer recycling. Despite attractive experimental achievements, insightful depolymerization kinetic modeling study is capable of providing information for better understanding polymer degradation process and reactor design in polymer industry. Herein, an improved analytical solution for depolymerization by chain‐end scission is derived and validated by numerical exact solution. The strength of the as‐derived analytical solution lies on its capability of capturing depolymerization kinetics of polymers with large degrees of polymerization and different initial distributions (e.g., Gamma, monodisperse, Poisson, Flory‐Schulz, exponential, and log‐normal distributions). Additionally, the changes in average properties of polymer are accessed by using a hybrid method based on the method of moment (MoM) and the improved analytical solution considering dimers in chain‐end scission process for the first time. Finally, kinetic insights into depolymerization of self‐immolative polymers are also gained by the MoM‐based model in parallel with two sets of experimental data. This work offers simulation protocols for a profound understanding of depolymerization kinetics and inspecting molecular properties during depolymerization.

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Modelling end-chain scission and recombination of linear polymers

Cited by 28 publications

References 9 publications

Experimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket Motor Internal Insulation

Experimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket Motor Internal Insulation

A continuous model for vapourisation of linear polymers by random scission and recombination

Analytical and numerical simulations of depolymerization based on discrete model: A chain‐end scission scenario

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