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

Staggs, J.E.J.

doi:10.1016/j.firesaf.2005.05.004

Cited by 18 publications

(13 citation statements)

References 12 publications

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“…This case, relevant for the thermal degradation of polymers such as polyethylene, has already been dealt with extensively in the literature [3,6,8]. However, it transpires, as will be seen presently, that when c 0 is large, good approximations for the relative weight-average molecular mass and the polydispersity during degradation may be calculated.…”

Section: Pure Random Scissionmentioning

confidence: 95%

“…Two earlier papers [6,9] consider the effect of recombination on models of pure random scission and end-chain scission.…”

Section: The General Bond-weighted Modelmentioning

confidence: 99%

“…Some authors [3] have attempted to employ relatively detailed mass transfer processes, however, following the approach of earlier papers [6,8,9], we shall adopt the simplest possible description, i.e. there exists a characteristic number of repeat units m v below which polymer molecules are volatile.…”

Section: Volatilisationmentioning

confidence: 99%

“…In a recent paper [6], the author analysed a continuous model for random scission with recombination and presented the general solutions of the continuous random scission model and the continuous recombination model. Discrete models have also been successfully applied in a number of situations and references [7][8][9][10][11] are a representative but incomplete selection.…”

Section: Introductionmentioning

confidence: 99%

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Discrete bond-weighted random scission of linear polymers

Staggs

2006

Polymer

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Section: Pure Random Scissionmentioning

confidence: 95%

“…Two earlier papers [6,9] consider the effect of recombination on models of pure random scission and end-chain scission.…”

Section: The General Bond-weighted Modelmentioning

confidence: 99%

Section: Volatilisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discrete bond-weighted random scission of linear polymers

Staggs

2006

Polymer

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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%

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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Interlinked population balance and cybernetic models for the simultaneous saccharification and fermentation of natural polymers

Doshi

Yeoh

et al. 2015

Biotech & Bioengineering

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Simultaneous Saccharification and Fermentation (SSF) is a process where microbes have to first excrete extracellular enzymes to break polymeric substrates such as starch or cellulose into edible nutrients, followed by in situ conversion of those nutrients into more valuable metabolites via fermentation. As such, SSF is very attractive as a one-pot synthesis method of biological products. However, due to the co-existence of multiple biochemical steps, modeling SSF faces two major challenges. The first is to capture the successive chain-end and/or random scission of the polymeric substrates over time, which determines the rate of generation of various fermentable substrates. The second is to incorporate the response of microbes, including their preferential substrate utilization, to such a complex broth. Each of the above-mentioned challenges has manifested itself in many related areas, and has been competently but separately attacked with two diametrically different tools, i.e., the Population Balance Modeling (PBM) and the Cybernetic Modeling (CM), respectively. To date, they have yet to be applied in unison on SSF resulting in a general inadequacy or haphazard approaches to examine the dynamics and interactions of depolymerization and fermentation. To overcome this unsatisfactory state of affairs, here, the general linkage between PBM and CM is established to model SSF. A notable feature is the flexible linkage, which allows the individual PBM and CM models to be independently modified to the desired levels of detail. A more general treatment of the secretion of extracellular enzyme is also proposed in the CM model. Through a case study on the growth of a recombinant Saccharomyces cerevisiae capable of excreting a chain-end scission enzyme (glucoamylase) on starch, the interlinked model calibrated using data from the literature (Nakamura et al., Biotechnol. Bioeng. 53:21-25, 1997), captured features not attainable by existing approaches. In particular, the effect of various enzymatic actions on the temporal evolution of the polymer distribution and how the microbes respond to the diverse polymeric environment can be studied through this framework.

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

Cited by 18 publications

References 12 publications

Discrete bond-weighted random scission of linear polymers

Discrete bond-weighted random scission of linear polymers

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

Interlinked population balance and cybernetic models for the simultaneous saccharification and fermentation of natural polymers

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