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471 results on '"Schartel, Bernhard"'

185. Modelling the vertical UL 94 test: competition and collaboration between melt dripping, gasification and combustion.

Author

Kempel, Florian, Schartel, Bernhard, Marti, Julio M., Butler, Kathryn M., Rossi, Riccardo, Idelsohn, Sergio R., Oñate, Eugenio, and Hofmann, Anja

Subjects
COMBUSTION, POLYTEF, BISPHENOL A, ACRYLONITRILE butadiene styrene resins, FINITE element method, POLYMERS
Abstract

An experimental and numerical investigation of the effect of bisphenol A bis(diphenyl phosphate) (BDP) and polytetrafluoroethylene (PTFE) on the fire behaviour of bisphenol A polycarbonate/acrylonitrile butadiene styrene (PC/ABS) in the vertical UL 94 scenario is presented. Four PC/ABS blends were discussed, which satisfy different UL 94 classifications due to the competing effects of gasification, charring, flame inhibition and melt flow/dripping. For numerical investigation, the particle finite element method (PFEM) is used. Its capability to model the complex fire behaviour of polymers in the UL 94 is analysed. The materials' properties are characterised, in particular the additives impact on the dripping behaviour during thermal exposure. BDP is an efficient plasticiser; adding PTFE prevents dripping by causing a flow limit. PFEM simulations reproduce the dripping and burning behaviour, in particular the competition between gasification and dripping. The thermal impact of both the burner and the flame is approximated taking into account flame inhibition, charring and effective heat of combustion. PFEM is a promising numerical tool for the investigation of the fire behaviour of polymers, particularly when large deformations are involved. Not only the principal phenomena but also the different UL 94 classifications and the extinction times are well predicted. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2015
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186. The influence of layered, spherical, and tubular carbon nanomaterials' concentration on the flame retardancy of polypropylene.

Author

Dittrich, Bettina, Wartig, Karen‐Alessa, Hofmann, Daniel, Mülhaupt, Rolf, and Schartel, Bernhard

Subjects
GRAPHENE, CARBON-black, MULTIWALLED carbon nanotubes, POLYPROPYLENE, NANOPARTICLES, ELECTRICAL resistivity, THERMAL conductivity
Abstract

The characteristic influences of increasing concentrations of graphene, expanded graphite (EG), carbon black (CB), and multiwall carbon nanotubes (MWNT) are investigated on pyrolysis, reaction to small flame, burning behavior, and on electrical, thermal, and rheological properties of flame retarded polypropylene (PP-FR). The property-concentration dependency is different for the various material properties, as threshold, linear, and leveling off functions were observed. Increasing concentrations of carbon nanoparticles resulted in a decrease in the electrical resistivity of the polymer by crossing the percolation threshold. The developing nanoparticle network changes melt flow behavior for small shear rates, increases thermal conductivity and therefore, affects the UL 94 classification and oxygen index. The onset temperature of PP decomposition is shifted to temperatures up to 37°C higher; the peak heat release rate is reduced by up to 74% compared to PP-FR. Both effects leveled off with increasing particle concentration. Among the four carbon nanomaterials tested, graphene presents superior influence on composite properties over the tested concentration range and outperforms commercial CB, MWNT, and EG. POLYM. COMPOS., 36:1230-1241, 2015. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2015
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187. Carbon-based nanofillers/Poly(butylene terephthalate): thermal, dielectric, electrical and rheological properties.

Author

Yin, Huajie, Dittrich, Bettina, Farooq, Muhammad, Kerling, Sabrina, Wartig, Karen-Alessa, Hofmann, Daniel, Huth, Christian, Okolieocha, Chimezie, Altstädt, Volker, Schönhals, Andreas, and Schartel, Bernhard

Subjects
POLYBUTENES, RHEOLOGY, CARBON nanotubes, MULTIWALLED carbon nanotubes, BUTENE, GLASS transition temperature, POLYBUTYLENE terephthalate
Abstract

The influence of distinct carbon based nanofillers: expanded graphite (EG), conducting carbon black (CB), thermally reduced graphene oxide (TRGO) and multi-walled carbon nanotubes (CNT) on the thermal, dielectric, electrical and rheological properties of polybutylene terephthalate (PBT) was examined. The glass transition temperature (Tg) of PBT nanocomposites is independent of the filler type and content. The carbon particles act as nucleation agents and significantly affect the melting temperature (Tm), the crystallization temperature (Tc) and the degree of crystallinity of PBT composites. PBT composites with EG show insulating behaviour over the tested concentration range of 0.5 to 2 wt.-% and hardly changed rheological behaviour. CB, CNT and TRGO induce electrical conductivity to their particular PBT composites by forming a conducting particle network within the polymer matrix. CNT reached the percolation threshold at the lowest concentration (<0.5 wt.-%), followed by TRGO (<1 wt.-%) and CB (<2 wt.-%). With the formation of a particle network, the flow behaviour of composites with CB, CNT and TRGO is affected, i.e., a flow limit occurs and the melt viscosity increases. The degree of influence of the carbon nanofillers on the rheological properties of PBT composites follows the same order as for electrical conductivity. Electrical and rheological results suggest an influence attributed to the particle dispersion, which is proposed to follow the order of EG < < CB < TRGO < CNT. [ABSTRACT FROM AUTHOR]

Published
2015
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188. Cover Picture: Macromol. Chem. Phys. 16/2006

Author

Braun, Ulrike, primary, Knoll, Uta, additional, Schartel, Bernhard, additional, Hoffmann, Thorsten, additional, Pospiech, Doris, additional, Artner, Johannes, additional, Ciesielski, Michael, additional, Döring, Manfred, additional, Perez-Graterol, Raul, additional, Sandler, Jan K. W., additional, and Altstädt, Volker, additional

Published
2006
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189. Novel Phosphorus‐Containing Poly(ether sulfone)s and Their Blends with an Epoxy Resin: Thermal Decomposition and Fire Retardancy

Author

Braun, Ulrike, primary, Knoll, Uta, additional, Schartel, Bernhard, additional, Hoffmann, Thorsten, additional, Pospiech, Doris, additional, Artner, Johannes, additional, Ciesielski, Michael, additional, Döring, Manfred, additional, Perez‐Graterol, Raul, additional, Sandler, Jan K. W., additional, and Altstädt, Volker, additional

Published
2006
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193. Fire Retardancy of Polymers

Author

Hornsby, Peter R, primary, Rothon, Roger N, additional, Takeda, Kunihiko, additional, Pelegris, Christine, additional, Kashiwagi, Takashi, additional, Lomakin, Sergei, additional, Zaikov, Gennady E, additional, Lefebvre, Jean-Marc, additional, Sheptalin, Roman A, additional, Kandola, Baljinder K, additional, Horrocks, A Richard, additional, Wang, Jianqi, additional, Gilman, Jeffrey W, additional, Flambard, Xavier, additional, Camino, Govanni, additional, Schartel, Bernhard, additional, Mutel, Brigitte, additional, Grisel, Michel, additional, Lopez Cuesta, Jose M, additional, De Moura Estevao, Luciana, additional, Marosi, Gyorgy, additional, Hull, T Richard, additional, Price, Dennis, additional, and Georlette, Pierre, additional

Published
2005
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