Spelling suggestions: "subject:"flameretardant"" "subject:"flameretardants""
61 |
Transcriptomics and Proteomics Applied to Developmental ToxicologyKultima, Kim January 2007 (has links)
Developmental toxicology is an important part of preclinical drug toxicology as well as environmental toxicology. Assessing reproductive and developmental toxicity is especially expensive and time demanding, since at least two generations of animals are needed in the tests. In light of this there is a great need for alternative test methods in many areas of developmental toxicity testing. The complete set of RNA transcripts in any given organism is called the transcriptome. Proteomics refers to the study of the proteins in a given organism or cell population. The work of this thesis has focused on the use of high throughput screening methods in transcriptomics and proteomics to search for molecular markers of developmental toxicity. We have studied the global gene expression effects of the developmentally toxic substance valproic acid (VPA) using microarray technology. Several genes were found that display the same gene expression pattern in vivo using mouse embryos as the pattern seen in vitro using the embryocarcinoma cell line P19. Based on these observations, the gene Gja1 was suggested as one potential molecular marker of VPA induced developmental toxicity and potential marker of histone deacetylase (HDAC) inhibition in vitro. Using 2D-DIGE technology, which measures relative protein abundances, the effect of neonatal exposure to the flame retardant PBDE-99 was studied in mouse brain (cortex, hippocampus and striatum) 24 hr after exposure. Differentially expressed proteins in the cortex and the striatum indicate that PBDE-99 may alter neurite outgrowth. Finally, we have suggested several improvements in the use of the 2D-DIGE technology. Novel methods for normalizing data were presented, with several advantages compared to existing methods. We have presented a method named DEPPS that makes use of all identified proteins in a dataset to make comprehensive remarks about biological processes affected.
|
62 |
Environmental occurrence and behaviour of the flame retardant decabromodiphenyl ethaneRicklund, Niklas January 2010 (has links)
The environmental occurrence and behaviour of the brominated flame retardant (BFR) decabromodiphenyl ethane (dbdpe) has only been studied to a limited extent. It is structurally similar to decabromodiphenyl ether (decaBDE), which makes it conceivable that dbdpe may also become an environmental contaminant of concern. A method for environmental analysis and comparative assessments of dbdpe and decaBDE was developed. Both BFRs were studied in: a mass balance of the Henriksdal WWTP in Stockholm (Paper I); an international survey of sewage sludge (Paper II); sediment along a transect from Henriksdal WWTP to the outer archipelago of Stockholm and from isolated Swedish lakes (Paper III); and a benthic food web from the Scheldt estuary (Paper IV). Dbdpe was found in sludge from every country surveyed, indicating that it may be a worldwide concern. The WWTP mass balance showed that virtually all of the BFRs were transferred from wastewater to sludge. A small fraction was emitted via the effluent, confirming emissions to the aquatic environment. In the marine sediment, the BFR levels close to the WWTP outfall were high. They decreased along the transect to low levels in the outer archipelago. The study of lake sediment showed a widespread presence of dbdpe in the Swedish environment and provided evidence that it originates from long range atmospheric transport. In the food web, dbdpe did bioaccumulate to a small extent which was similar to decaBDE. The transfer of the BFRs from sediment to benthic invertebrates was low, while transfer from prey to predator was higher. Biodilution was observed rather than biomagnification. This work suggests that the persistence, the susceptibility to long range atmospheric transport, and the potential for bioaccumulation are similar for dbdpe and the regulated decaBDE that it is replacing. Thus, there is a risk that a problematic environmental pollutant is being replaced with a chemical that is equally problematic. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.
|
63 |
A method of chemical aftertreatment for the reduction of free formaldehyde release of a durable flame retardant finished cotton fabricSaleem, Saima January 2015 (has links)
This thesis aims at developing a method of chemical aftertreatment for reduction of free formaldehyde release of a tetrakis (hydroxymethyl) phosphonium chloride (THPC) urea precondensate, ammonia cured durable flame retardant finished cotton fabric, by preventing the formation of free formaldehyde. Formaldehyde is toxic and carcinogenic. According to the worldwide standards, acceptable limit of free formaldehyde release, for the fabrics that have skin contact, is only 75 ppm (measured by water extraction method). In this research, a cotton fabric flame retardant finished in an industrial plant in Pakistan is used. Fabric is finished by the application of THPC urea precondensate and ammonia cured, oxidized and washed. After finishing, it is not aftertreated with sodium metabisulfite that is a commonly used aftertreatment method for the reduction of free formaldehyde release. Aftertreatment with sodium metabisulfite has various problems that include large number of hot washings and there is an increase in the formaldehyde release during fabric storage. If the fabric has 75 ppm of free formaldehyde, there is often an increase in free formaldehyde release during fabric storage. There is a very limited research on the aftertreatment methods and few reports of application of these aftertreatments on flame retardant fabrics have been published. In this research, two methods of aftertreatments are developed to reduce the free formaldehyde contents to 75 ppm or less. One is the aftertreatment with a combination of resorcinol 1% and diethylene glycol 4%. The other is the combination of resorcinol 1% and boric acid 6%. For both these aftertreatments, ammonium acetate 0.5% is used as a catalyst. Fabric is padded with the solution and then dried at 130̊ C for 8 minutes. After drying, fabric is rinsed with water at 40̊ C. The aftertreatment methods developed in this research have shown a long term effect in keeping the formaldehyde release below 75 ppm during fabric storage that is not available with other conventional aftertreatment methods. These aftertreatment methods have no adverse effect on the flame retardancy of the THPC ammonia cured finished fabric and the fabric is soft as compared to the original flame retardant finished fabric and to the fabric after treated with existing methods. These new developed methods have industrial application because there is no use of any solvent and there is no use of any special equipment for the aftertreatment.
|
64 |
Optimisation de la formulation et de la tenue aux hautes températures d’un béton à base d’époxyde / Optimization of the formulation and Behavior at high temperatures of epoxy based polymer concrete.Elalaoui, Oussama 11 February 2012 (has links)
La durabilité des matériaux employés en génie civil est remise en question par le vieillissement physico-chimique de ces matériaux pouvant engendrer des dégradations significatives qui peuvent mettre en péril la stabilité des structures du génie civil. Pour pallier à certains inconvénients des bétons hydrauliques, l'utilisation des matériaux composites à l'instar des bétons de résine, qui possèdent des qualités remarquables par rapport aux matériaux de construction conventionnels, s'avère très intéressant.À l'heure actuelle, les freins majeurs quant aux développements des bétons résines sont d'une part le coût de la résine dont le taux varie, selon l'application industrielle, de 5% à 25% et d'autre part leurs comportements aux températures élevées et au feu puisque les liants dans ces bétons sont des substances organiques qui résistent beaucoup moins à la chaleur que les matières inorganiques. L'objectif de l'étude est de favoriser le développement des bétons résines par la diminution du taux de la résine en optimisant les constituants du béton et l'amélioration de leurs ténues aux températures élevées par l'ajout des additions tout en assurant des performances mécaniques raisonnables. L'optimisation de la formulation du béton est menée sur deux étapes ; la première vise à optimiser le squelette granulaire (sable 0/4 et Gravier 4/10, silico-calcaires) expérimentalement en confrontant les résultats à ceux issus du modèle d'empilement compressible. La deuxième étape vise à optimiser la fraction massique du liant époxydique (6%, 9%, 13% et 16%) sur la base des essais de caractérisation mécaniques et physiques. Le deuxième objectif de l'étude a était menée par l'ajout des ignifugeants appartenant à deux familles différentes c'est-à-dire les hydroxydes de métal et les produits phosphorés inorganiques. Les propriétés physiques, thermiques et mécaniques des bétons additionnées et témoins, avant et après exposition à un cycle de chauffage-refroidissement de la température ambiante à une température de consigne de 100°C, 150°C, 200°C, 225°C et 250 °C avec une vitesse de montée fixée à 0.5°C/min, ont été évaluées par les techniques de caractérisation usuelles en plus des essais d'analyses chimiques et thermiques.Cette étude aboutit à la formulation d'un béton optimal en terme de composition et à évaluer l'effet de l'addition des ignifugeants surtout sur les propriétés thermiques et mécaniques.Mots clés : béton de résine, optimisation, température élevée, ignifugeants, propriétés mécaniques, propriétés physiques, propriétés thermiques. / The material used in civil engineering applications must be re-evaluated because of their physicochemical ageing which can generate significant damages and hence put the stability of civil engineering structures in danger.The replacement of the hydraulic concrete by composite materials as the polymer concrete which offer higher properties compared to conventional construction materials seems to be very interesting. At the present time, the major restrain for the development of polymer concrete are on one hand the cost of the polymer whose ratio varies according to the industrial applications between 5% and 25%, and on the other hand their behaviour when exposed to high temperatures or fire since the resin acting as binder in these polymer concretes are organic substances which are more sensitive to heat than the inorganic matters as cement.The aim of this study was to help the development of polymer concrete by optimizing the formulation and improving their behaviour when exposed the high temperatures by incorporating additions while keeping acceptable mechanical performances.The optimisation of the formulation is done in two steps; the first step consists of optimising the aggregates content (Natural River sands 0/4 mm and crushed gravels 4/10 mm). Experimental results are compared to those given by means Compressible Packing Model. The second step consists of optimizing the amount of polymer (6%, 9%, 13% et 16%) based on mechanical and physical tests.The second aim of this work was fulfilled by the incorporation of two flame retardants belonging to metal hydroxide and phosphorous components types. Physical, thermal and mechanical properties of concretes with or without flame retardant, before and after heating-cooling cycle from ambient temperature to exposure temperature of 100°C, 150°C, 200°C, 225°C et 250 °C with a rate of 0.5°C/min, are evaluated by common characterisation tests besides chemical and thermal ones. This study has leading to obtaining an optimum polymer concrete and evaluates the effect of flame retardant particularly on the thermal and mechanical properties.Keywords: polymer concrete, optimization, high temperatures, flame retardant, mechanical properties, physical properties, thermal properties.
|
65 |
Kartläggning av inherent flamskyddade textilier : hur påverkar dessa hälsa och miljö? / Identification of inherent flame retardants in textile materials : how do these affect health and the environment?Ell, Malin, Hult, Anna, Risberg, Josephine January 2021 (has links)
Flamskyddsmedel i textila material används för att förhindra eller fördröja brand. Lagar och standarder ställer krav på att textila varor i offentliga miljöer har ett flamskydd. Flamskyddade textilier används också av de yrkesgrupper som utsätts för brandrisk på arbetsplatsen. Användningen av flamskydd har ökat sedan 1970-talet. På 1980-talet började hälso- och miljöriskerna med användningen av dessa att uppmärksammas. Detta har lett till reglering för användning av de flamskydd som innehåller klor och brom. Utveckling av halogenfria flamskyddsmedel som hälso- och miljövänliga alternativ pågår. Även möjligheten att integrera flamskyddsmedlet i textilfibern ses som ett hälso- och miljövänligt alternativ. Integrering av ett inherent flamskydd sker antingen i form av sampolymerisation med den textila polymeren eller vid extrudering av garnet. Inherent flamskydd i textila material marknadsförs som hälso- och miljövänliga då det inte avges från det textila materialet vid tvätt och slitage. Dessa aspekter innefattar endast den del av det textila materialets livslängd som innebär användning av textilen. Information om påverkan på hälsa och miljö vid produktion och bortförskaffande av ett inherent flamskyddade textilier är bristfällig. Resultatet visar att ämnen och föreningar som ger det textila materialet ett inherent flamskydd kan vid dessa steg i materialets livscykel orsaka skada på både människa och natur. Vid framställning och hantering av dessa ämnen kan en felaktig sådan leda till utsläpp. Dessa utsläpp kan orsaka luftföroreningar och försurning i mark och vatten. Vid bortförskaffande av inherent flamskyddade textilier är deponi vanligt vilket i sin tur leder till förbränning av avfallet. Vid förbränning avges deponigaser som är toxiska för hälsa och miljö. / Flame retardants in textile material is used to prevent or delay fire. Laws and standards require that textile goods used in public environments are flame protected. Flame retardant textiles are also used by the occupational groups exposed to the risk of fire in the workplace. The use of flame retardants has increased since the 1970s. In the 1980s, the health and environmental risks associated with their use began to receive attention. This had led to regulations for the use of flame retardants containing chlorine and bromine. The development of halogen-free flame retardants as health and environmentally friendly alternatives is ongoing. The possibility of integrating the flame retardant into the textile fiber is also seen as a health and environmentally friendly alternative. Integration of an inherent flame retardant can be done either during copolymerization of the textile polymer or by adding an additive by the extrusion of the yarn. Inherent flame retardants in textile materials are marketed as health and environmentally friendly as they’re not emitted from the textile material during wash and wear. These aspects include only the part of the lifespan of the textile material that involves the use of the textile. Information of the impact on health and environment during the production and disposal stage of an inherently flame-retardant textile is insufficient. The results show that substances and compounds giving the textile material an inherent flame protection can at these stages in the material life cycle cause damage to both humans and nature. An incorrect handling in the production phase of these substances can lead to emissions. These emissions can cause air pollution and acidification in soil and water. Landfill is common at disposing of inherently flame-retardant textiles which later leads to combustion of the materials. During combustion toxic landfill gases are released into the environment.
|
66 |
Development and Investigation of High-Performance Fire Retardant Polypropylene Nanocomposites via High Energy ElectronsXiao, Dan 04 October 2017 (has links)
Polypropylene (PP) has excellent mechanical and chemical properties. Thus, it is used in a wide range of applications. However, like for most polymers, the high flammability of PP limits its application in various fields requiring specific flame-retardant standards. Some of halogenated flame retardants are restricted by European Community directives ROHs, WEEE and REACH. Now metallic hydroxides flame retardants are widely used in industry, but the high loading (about 60 wt %) seriously destroys the mechanical properties of polymeric materials. To improve the performance of flame retardant polymers, an environment-friendly electron beam (EB) technology has been successfully used in modifying flame retardant and polymer matrix.
In this work, high efficient functional intumescent flame retardants and functional surfactant are designed and prepared for EB technology. In-depth studies the thermal stability, fire behavior and mechanical properties of these flame retardant PP composites have been studied. The possible graft-linking and cross-linking mechanisms of such EB modified composites can be well established. Specially, it is shown that the novel surfactant has better thermal stability in comparison to traditionally used modifiers.
Another part of this work deals with the exploration of novel allylamine polyphosphate (AAPP) as flame retardant crosslinker for PP by electron beam (EB) treatment. Multifunctional AAPP showed unique efficient intumescent flame retardant properties. The limiting oxygen index (LOI) value and the effective melt drop resistance in UL-94 test of multifunctional flame retardant PP composites is greatly enhanced. In the cone calorimeter test, a reduction of peak heat release rate, total heat release and smoke production is achieved. Moreover, EB treatment increased the thermal stability of these designed flame retardant PP composites. Furthermore, AAPP provided an excellent quality of char residue in the combustion stage due to P−N−C and P−O−C structure. In addition, synergistic mechanism of AAPP with montmorillonite (MMT) was explored.
Finally, different EB parameters have been used to modify fire retardant polymer nanocomposites. The effects of EB treatment on thermal stability, fire behavior and mechanical properties of fire retardant PP nanocomposites have been discussed. The heat release, the production of toxic gases and the mass loss of EB modified fire retardant PP nanocomposites are delayed in accordance to the result of cone calorimeter test. Based on these results high performance fire retardant polymer nanocomposites can be developed for industrial applications such as insulated material of wire, cable, etc.
|
67 |
Substance flow analysis of brominated flame retardants in vehicles / 自動車由来の臭素系難燃剤の物質フロ-分析Liu, Heping 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23183号 / 工博第4827号 / 新制||工||1754(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 酒井 伸一, 教授 田中 宏明, 准教授 平井 康宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
|
68 |
Élaboration de plastifiants ignifugeants à base de dérivés lipidiques pour formulations PVC / Elaboration of lipidic flame retardant plasticizers for PVCBocqué, Maëva 25 November 2015 (has links)
E PVC est l'un des polymères les plus employés dans les matériaux actuels et l'adjonction de plastifiants permet de modifier ses propriétés (température de transition vitreuse, module…) permettant ainsi l'utilisation de ce polymères dans des applications où de la souplesse est requise (textiles enduits, par exemple). Actuellement, les phtalates sont les plastifiants les plus utilisés même s'ils sont de plus en plus décriés du fait de leur toxicité. Le développement de nouveaux agents plastifiants est un domaine de recherches intenses et les matières premières bio-sourcées s'avèrent être une alternative intéressante aux plastifiants pétro-sourcés. Le travail de cette thèse se propose d'investiguer le développement de plastifiants du PVC bio-sourcés de type lipidique possédant de surcroit des propriétés ignifugeantes évitant ainsi l'ajout d'additifs supplémentaires dans les formulations de PVC devant résister au feu. Dans un premier temps, l'oléate, le linoléate de méthyle et le diacide (D18 : 1) ont été fonctionnalisés par modification chimique de leurs groupements ester et/ou de leurs insaturations pour mener à des dérivés lipidiques phosphorés. Cinq candidats plastifiants bio-sourcés ont ainsi pu être synthétisés et le scale up de la synthèse de l'un des candidats à l'échelle du kilogramme a pu être réalisé dans le cadre de cette thèse. Dans un deuxième temps, des tests de plastification du PVC avec divers candidats ont été réalisés en collaboration avec la société Serge FERRARI. L'étude des propriétés thermiques, mécaniques et thermomécaniques des films de PVC plastifiés obtenus, comparativement au plastifiant phtalate DINP et au plastifiant bio-sourcé commercial RADIA 7295, a permis d'éliminer différents candidats pour n'en finalement retenir que deux. Des profils de dégradation thermique satisfaisants, des basses valeurs de Tg, des allongements à la rupture importants (320 et 365 % respectivement) et proches de ceux obtenus avec le DINP, ont confirmé l'efficacité plastifiante de ces deux composés phosphorés bio-sourcés. Les tests au feu LOI et au cône calorimètre ont également prouvé le caractère ignifugeant de ces deux composés qui conduisent à des résultats du même ordre de grandeur que ceux atteints avec le plastifiant phosphonate commercial de référence S141 / Poly(vinyl chloride) is one of the most manufactured and consumed thermoplastics in the world. The addition of plasticizers allows modifying its properties (glass transition temperature, modulus…) and then to use this polymer for applications where flexibility is needed (coated textiles, for instance). Nowadays, phthalates are the main candidates for PVC even if they have been more and more controversed due to their possible toxicity. To substitute these petro-based plasticizers, researches are focused on alternative plasticizers based on bio-based raw materials. This PhD work proposes to investigate the development of new bio-based plasticizers for PVC, from lipidic derivatives, and having simultaneously flame retardant properties, avoiding the addition of any other additives in PVC during compounding. In the first part, methyl oleate, methyl linoleate and diacid D18 : 1 have been functionalized by modification of their ester groups and/or their doubles bonds to give phosphorylated lipidic derivatives. Thus, five bio-based plasticizers have been synthesized and the synthesis of one candidate on the scale of the kilogram has been successfully performed during this PhD work. Secondly, the plasticizing efficiency of several candidates with PVC has been evaluated in collaboration an industrial company. Thermal, mechanical and thermomechanical properties of the obtained soft PVC films were studied, in comparison with those obtained with the phthalate plasticizer DINP and the commercial bio-based plasticizer RADIA 7295. These analyses allowed the disposal of some of the bio-based plasticizers to finally keep only two candidates. Satisfying thermal degradation profiles, low Tg, and important elongation at break values (320 % and 365 % respectively) close to those obtained with DINP, confirmed the plasticizing efficiency of these two bio-based phosphorylated plasticizers. Fire tests like the LOI test and the cone calorimeter also proved the flame retardant properties of these two candidates, leading to similar results than the ones reached with the phosphonate plasticizer S141
|
69 |
Synthesis and Characterization of Free-acid Derivatives and Corresponding Ionomers of Poly(L-lactic acid)Tommey, Tyler 25 August 2020 (has links)
No description available.
|
70 |
Aufbau eines Reportergenassays zur Untersuchung der Wechselwirkung endokriner Disruptoren mit der T 3-regulierten TransaktivierungHofmann, Peter Josef 27 August 2008 (has links)
Das Schilddrüsenhormon Triiodthyronin (T3) ist ein essenzieller Regulator physiologischer Prozesse der Entwicklung, des Wachstums und im Intermediärstoffwechsel. Täglich werden zahlreiche natürliche und synthetische Stoffe aufgenommen, die mit dem endokrinen System interferieren und deshalb als Endokrine Disruptoren (ED) bezeichnet werden. Zur Untersuchung einer direkten Interferenz von ED mit den Schilddrüsenhormonrezeptoren (TR) und ihrer transkriptionellen Aktivität wurde im Rahmen dieser Arbeit ein neues Luziferase-basiertes T3 Reportergensystem mit TRalpha1-transfizierten humanen Leberzellen aufgebaut. Durch Validierung mit dem synthetischen TR-Agonisten GC-1 und dem Antagonisten NH-3 konnte nachgewiesen werden, dass dieser Assay ein hoch-sensitives System zur Analyse von agonistischen sowie antagonistischen Effekten von Testsubtanzen darstellt. Zur Bestimmung der endokrinen Aktivitäten einiger humanrelevanter Vertreter aus den Stoffkategorien der Nahrungsmittel, Kosmetika, Pestizide und Industriechemikalien wurden Dosis-Wirkungskurven in Aktivierungs- und T3-Kompetitionsexperimenten ermittelt. In mikromolaren Konzentrationen wirkten von insgesamt 21 Testsubstanzen einige als reine Agonisten oder Antagonisten während andere gemischt agonistische/antagonistische Effekte hatten. Aufgrund ihrer hier beobachteten Effekte und der gegebenen Humanexposition wird eine eingehendere Analyse von 4-Methylbenzyliden Campher, 4-Nonylphenol, Acetochlor, Benzophenon 2, Benzophenon 3, Bisphenol A, Genistein, Octylmethoxycinnamat, Tetrabromobisphenol A und Xanthohumol empfohlen. Außerdem erwiesen sich einige Metaboliten von Schilddrüsenhormonen als potente Agonisten im T3-Reportergenassay und bedürfen weiterer Aufmerksamkeit. Für die molekulare Charakterisierung der Einflüsse solcher Substanzen auf die T3-regulierte Transaktivierung konnte mit dem hier etablierten Bioassay ein zuverlässiges neues Testsystem für reproduzierbare Screeningserien geschaffen werden. / Triiodothyronine (T3) is a crucial regulator of many physiological processes during development, growth and metabolism. A variety of natural and synthetic substances, which are collectively termed endocrine disrupters (ED) due to their interference with the endocrine system, is taken up on a daily base. A novel luciferase-based T3-responsive reporter gene system employing a human liver cell line transfected with thyroid hormone receptor (TR) alpha1 was established in this work to elucidate the potential molecular interference of certain ED with TR and their transcriptional activity. This assay was validated to be a highly sensitive and reliable tool for analyzing agonistic and antagonistic effects of test compounds using the synthetic TR agonist GC-1 and the antagonist NH-3. Dose-response data of test compounds contained in food, cosmetics, pesticides, plasticizers and other industrial chemicals were obtained after applying the substances alone in activation assays or in combination with T3 in competition assays. In total 21 test compounds were screened of which some acted as pure agonists or antagonists while others were mixed agonists/antagonists in the micromolar concentration range and only one was without effect. Follow-up studies are recommended for some of these substances with regard to their effects as determined in this bioassay and in light of information known on human exposure, i.e., 4-methylbenzyliden camphor, 4-nonylphenol, acetochlor, benzophenone 2, benzophenone 3, bisphenol A, genistein, octylmethoxycinnamate, tetrabromobisphenol A and xanthohumol. In addition some endogenous metabolites of thyroid hormones were surprisingly potent agonists in the T3 reporter gene assay and merit further attention. The novel bioassay established here represents a reliable tool for the screening and molecular characterization of substances interfering with T3-mediated transactivation of gene expression.
|
Page generated in 0.0621 seconds