Investigation on kinetics of thermal decomposition in polysiloxane networks used as precursors of silicon oxycarbide glasses

Schiavon, Marco A.; Redondo, Simone Ungari Azzolino; Pina, S.R.O.; Yoshida, Inez Valéria Pagotto

doi:10.1016/s0022-3093(02)01009-8

Cited by 95 publications

(71 citation statements)

References 21 publications

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“…Siloxane compounds decompose under high temperature levels in the combustion chamber [8,9], and the landfill gas must be analysed because a small quantity of siloxanes can cause severe damage to the engines when deposited over a longer period [10,11]. Consequently some engine manufacturers recommend siloxane limits in landfill gas in order to ensure the maintenance operations are not dependent on the siloxane levels [12].…”

Section: Componentmentioning

confidence: 99%

Analysis of damage caused by siloxanes in stationary reciprocating internal combustion engines operating with landfill gas

Alvarez-Florez

Egusquiza

2015

Engineering Failure Analysis

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Failures in reciprocating internal combustion engines operating with landfill gas are not uncommon. In general, damage is located in the combustion chamber surfaces and in the ring grooves, where a layer of non-volatile combustion products is deposited. These deposits attached to the surfaces reduce heat transfer and increase inner temperature, which produces a knocking phenomena damaging the crank bearings and fusing of the piston head material. Lubrication problems also appear due to the formation of a layer of soft paste silicone deposits in the rings grooves, which increases friction losses and accelerates wear on cylinder and rings. In this paper, some typical examples of damaged engines are presented. The deposits found were analysed using Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy (SEM-EDX). Additionally, the engine oil used was also analysed by Infra-Red Spectrometry (IR) and the results were compared with known organo-compounds. A method to detect incipient failure caused by organo-compounds contained in landfill gas is introduced. Silica appears in the layers covering the combustion chamber, as well as silicone compound in the top cylinder zone, piston and ring grooves. Damage is associated with siloxanes (organo-silicon compounds) contained in the landfill gas, which decompose in the combustion chamber, generating silicic acid and formaldehyde under the high temperature conditions throughout the combustion processes. Dear EditorThank you for agreeing to review the following manuscript, we would like to thank also the reviewers for the previously received comments. We want to extend our appreciation for taking the time and effort necessary to provide such guidance.As suggested by the editor a throughout revision of the paper has been carried out and the comments of the reviewer has been 100 % included in the current version of the manuscript. All changes on the original version of the manuscript appear in red in the current version.The reviewer commented the first half of manuscript, but his recommendations have been extended to the whole manuscript. Reviewer: 1 ADDITIONAL COMMENTS TO THE AUTHOR:The new Research Highlights according the magazine rules has been uploaded. Yours sincerelyJesus Alvarez-Florez *Detailed Response to Reviewers HighlightsThe main types of damage found in ICE using landfill gas have been studied Combustion of fuel with siloxanes produces two types of residues Residues attach to combustion chamber surfaces reducing the heat transfer Residues also attach to piston ring grooves causing lubrication problems A method to prevent damage based in engine oil IR analysis is presented ABSTRACTFailures in reciprocating internal combustion engines operating with landfill gas are not uncommon. In general, damage is located in the combustion chamber surfaces and in the ring grooves, where a layer of non-volatile combustion products is deposited. These deposits attached to the surfaces reduce heat transfer and increase inner temperature, which produces a k...

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Section: Componentmentioning

confidence: 99%

Analysis of damage caused by siloxanes in stationary reciprocating internal combustion engines operating with landfill gas

Alvarez-Florez

Egusquiza

2015

Engineering Failure Analysis

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“…% loss and it might be due to the elimination of either lineal or cyclic chains from PDMS and OPU dispersed in the silica matrix [34] . The weight loss from 450 °C up to 630 °C (30 wt.…”

Section: Modulation Of the Hydrophilic Character And Influence On Thementioning

confidence: 99%

Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxano

Jiménez-Gallegos¹,

Téllez-Jurado²,

Rodríguez‐Lorenzo³

et al. 2011

Bol. Soc. Esp. Ceram. Vidr.

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Organic-inorganic hybrid materials are known for their outstanding chemical and physical properties. Although some studies have been published regarding the use of hybrids for biomedical applications, relationship between hydrophilic character and biodegradation, bioactivity and biocompatibility has not been studied yet. The sol-gel method has been chosen for the manufacturing of siloxane-polyurethane hybrids for the exceptional potential of the method to obtain nanostructured materials. The effect of the amount of the urethane oligomer (OPU) on the structure, hydrophilic character, degradability, bioactivity and citotoxicity was investigated. Gelling time of these hybrids increases linearly with the decrease on the Siloxane/OPU ratio up to an 80/20 value. Hydrophilic character of the hybrids can be modulated and affects dramatically the degradation rate of the specimens. A hybrid with a 50/50 Siloxane/OPU ratio displayed an appropriate degradation rate, bioactivity and lack of cell toxicity that makes this material a candidate for further studies for applications in bone regeneration.Keywords: Sol-gel process; Biomedical applications; Hybrid Materials; Bioactivity; Polyurethane. Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxanoLos materiales híbridos Orgánico-Inorgánico son conocidos por sus excepcionales propiedades químicas y físicas. Aunque se han publicado algunos estudios respecto al uso de híbridos para aplicaciones biomédicas, aun faltan estudios que determinen la relación que existe entre el carácter hidrofílico de estos materiales y las propiedades que les permiten ser utilizados como biomateriales: degradación, bioactividad y biocompatibilidad. El método sol-gel se ha escogido para la fabricación de híbridos debido a la posibilidad de obtener materiales nanoestructurados que comprenden un componente orgánico y un inorgánico. Se investigó el efecto de la cantidad del olígomero de uretano (OPU) sobre la estructura, el carácter hidrofílico, la degradabilidad, la bioactividad y la citotoxicidad. El tiempo de gelificación de estos híbridos incrementa linealmente con la disminución en la relación Siloxano/OPU hasta un valor de 80/20. El carácter hidrofílico de los híbridos se puede modular y afectar considerablemente la velocidad de degradación de las muestras. Un híbrido con una relación 50/50 Siloxane/OPU muestra una velocidad de degradación, una bioactividad y falta de toxicidad que hacen a este material un candidato para futuros estudios para aplicaciones en regeneración ósea.

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“…Siliconas, que não são derivadas do petróleo, têm sido comercializadas desde os anos 1940 tendo, desde então, várias aplicações industriais [18]. Podem também ser o insumo para obtenção de materiais cerâmicos do tipo Si/C/O, chamados oxicarbetos de silício, oferecendo uma rota fácil e de custo relativamente baixo [19,20] na formação deste sistema. A conversão polímero-cerâmica geralmente é acompanhada por retração e volatilização de orgânicos, causando perda de massa [21].…”

Section: Introductionunclassified

Efeito da adição de polímero precursor cerâmico na sinterização de alumina

Godoy

Bressiani

2010

Cerâmica

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ResumoForam estudados os efeitos da adição de polímero precursor na sinterização, microestrutura e dureza da alumina. O polímero inorgânico polifenilmetilvinilhidrogenosilsesquioxano (PPS) foi utilizado como aditivo em cerâmicas de alumina sinterizadas a 1650 °C. Os materiais sinterizados foram caracterizados por dilatometria, determinando-se a densidade aparente por picnometria de hélio, pela análise de carbono total, por difração de raios X, por microscopia eletrônica de varredura, espectrometria de energia dispersiva de raios X e por análise de indentação Vickers para determinação de dureza e tenacidade a fratura. Foram obtidas fases heterogêneas de Si 2 Al 4 O 4 N 4 nas amostras com PPS. Dentre as amostras analisadas, a que contém 5% de PPS apresentou dureza e tenacidade à fratura superiores à da alumina pura. A preparação de compósitos cerâmicos com pequenas quantidades de polímero precursor mostrou-se um processo adequado para cerâmicas à base de alumina, sendo uma rota simples de conformação com grande potencial para a obtenção de peças com geometria complexa. Palavras-chave: polímero inorgânico, polissiloxano, microestrutura, alumina. AbstractThe effects of the addition of precursor polymer on sintering, microstructure and hardness of alumina ceramics were studied.

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Investigation on kinetics of thermal decomposition in polysiloxane networks used as precursors of silicon oxycarbide glasses

Cited by 95 publications

References 21 publications

Analysis of damage caused by siloxanes in stationary reciprocating internal combustion engines operating with landfill gas

Analysis of damage caused by siloxanes in stationary reciprocating internal combustion engines operating with landfill gas

Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxano

Efeito da adição de polímero precursor cerâmico na sinterização de alumina

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