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Etablierung und Optimierung der Error-Prone-PCR und eines Aktivitätsscreenings für Styrol-MonooxygenasenBorn, Ariane 01 July 2011 (has links)
Styrol-Monooxygenasen (SMOs) spielen im bakteriellen Abbau von Styrol eine wichtige Rolle. Sie epoxidieren den Kohlenwasserstoff zu (S)-Styroloxid und waren bis vor kurzem vor allem aus Gram-negativen Vertretern wie Pseudomonaden bekannt. Das Grampositive nocardioforme Bodenbakterium Rhodococcus opacus 1CP kann Styrol als Energie- und Kohlenstoffquelle nutzen und verfügt über zwei Typen von SMOs. Neben StyA2B, einer fusionierten FAD:NADH-Oxidoreduktase (StyB) und Monooxygenase (StyA2) findet sich eine weitere Monooxygenase StyA1, deren Gen direkt stromaufwärts zu styA2B lokalisiert ist. Zusätzlich zum natürlichen Fusionsprotein StyA2B gelang kürzlich die Konstruktion künstlicher Fusionen StyAL1B und StyAL2B aus Pseudomonas fluorescens ST.
Um sowohl StyA1/StyA2B als auch die künstlichen Fusionen StyAL1B und StyAL2B für eine biotechnologische Anwendung nutzen zu können, wurde im Rahmen dieser Arbeit angestrebt, ihre spezifische Oxygenierungsaktivität (StyA1/StyA2B: 0,24 U/mg) mit Hilfe der error prone PCR zu erhöhen. Um Veränderungen der katalytischen Aktivität in
einer großen Zahl von Mutanten schnell zu erkennen, ist ein einfacher Screeningtest erforderlich. Die Fähigkeit von SMOs zur Oxidation von Indol zu blauem Indigo bietet diese Möglichkeit. Allerdings ist hierfür die Expression löslicher Proteine eine wesentliche Voraussetzung. Versuche zur Veränderung der Gene styA2B und styA1A2B mit Hilfe eines kommerziellen error prone PCR Kits lieferten ca. 300 bis 1.200 mutmaßlich veränderte Klone, welche jedoch keinerlei Aktivität für den Indolumsatz zeigten. Als Ursache wurde eine Expression der Proteine in Form inaktiver Inclusion Bodies vermutet.
Die Fusionsproteine StyAL1B und StyAL2B bilden lösliches Protein, welche Indol zum blauen Farbstoff Indigo umsetzen. Verschiedene Kultivierungsbedingungen wurden auf den Umsatz von Indol untersucht. Dabei wurde erkannt, dass die Klone sich nicht identisch bezüglich ihrer Proteinlöslichkeit verhalten. Mit Hilfe dieser Ergebnisse wurde ein Test für das Aktivitätsscreening von Styrol-Monooxygenasen auf Platte entwickelt. Die Erhöhung der NaCl-Konzentration im Medium steigerte die Indoloxidation, welche sich jedoch durch zusätzliche physiologisch Faktoren schwer beeinflussen lassen.
Auch für die Fusionsproteine erfolgte die Durchführung einer error prone PCR. Der Schritt der error prone PCR stellte kein Problem dar, jedoch die Einbindung des veränderten Genfragmentes in den Vektor, beziehungsweise dessen Transformation in E. coli. Alternative Strategien, wie die Nutzung alternativer DNA Polymerasen und eines konventionellen Konzepts, bei dem veränderte Gene in geschnittene Expressionsvektoren ligiert werden, führte zu keinen detektierbaren Klonen.
Die Kultivierung von identischen Klonen auf Festmedium wirkte sich aufgrund nicht näher identifizierter Einflüsse auf das Verhalten bezüglich der Indoloxidation sehr unterschiedlich aus. Um diese Einflüsse zu minimieren, erfolgte die Untersuchung des Systems in einer Flüssigkultur. Im Blickpunkt stand hierbei die Indigoproduktion von E. coli BL21 (pET_StyAL2B) die in Abhängigkeit der optischen Dichte der Kultur untersucht wurde.:Eidesstattliche Erklärung II
Danksagung III
Zusammenfassung IV
Abstract VI
Abbildungsverzeichnis XI
Tabellenverzeichnis XIII
Abkürzungsverzeichnis XIV
1 Einleitung 1
1.1 Styrol - ein Produkt der Industrie . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Styrol-Monooxygenasen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Abbauwege von Styrol . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 Struktur, Vorkommen und Eigenschaften klassischer Zweikomponenten
Styrol-Monooxygenasen . . . . . . . . . . . . . . . . . . . . 4
1.2.3 Das neuartige Styrol-Monooxygenase-System StyA1/StyA2B aus
Rhodococcus opacus 1CP . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.4 Künstlich verlinkte SMO aus Pseudomonas uorescens ST . . . . . 7
1.2.5 Biotechnologischer Einsatz von Styrol-Monooxygenasen . . . . . . . 8
1.3 Strategien des Protein-Engineering . . . . . . . . . . . . . . . . . . . . . . 9
1.3.1 Arbeitsmethoden zur Veränderung von DNA . . . . . . . . . . . . . 9
1.3.2 Error prone PCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4 Arbeitsziele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Material und Methoden 13
2.1 Bakterienstämme und Plasmide . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Kultivierungsmedien und -bedingungen . . . . . . . . . . . . . . . . . . . . 14
2.2.1 Kultivierungsmedien . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.2 Kultivierungstemperaturen . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 Polymerase-Kettenreaktion (PCR) . . . . . . . . . . . . . . . . . . . . . . 16
2.3.1 Primer und Primerdesign . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3.2 Standard-PCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Fehlerbehaftete Polymerase-Kettenreaktion (epPCR) . . . . . . . . . . . . 17
2.4.1 Synthese der mutagenen Megaprimer . . . . . . . . . . . . . . . . . 18
2.4.2 EZClone Reaktion . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.3 Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.4 Modi zierung des Protokolls des EZClone Reaktion Schrittes . . . . 20
2.5 Aufreinigung von PCR-Produkten aus der Lösung . . . . . . . . . . . . . . 20
2.6 TAE-Agarose-Gelelektrophorese . . . . . . . . . . . . . . . . . . . . . . . . 20
2.7 DNA-Extraktion aus Agarosegelen . . . . . . . . . . . . . . . . . . . . . . 21
2.8 Bestimmung der DNA-Konzentration . . . . . . . . . . . . . . . . . . . . . 21
2.9 Restriktionsverdau von DNA . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.10 Ligation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.11 Herstellung von kompetenten Zellen (E.coli DH5ff, E. coli BL21) . . . . . 23
2.11.1 Chemisch kompetente Zellen nach der CaCl2-Methode (42) . . . . . 23
2.11.2 TOP10 chemischkompetente Zellen . . . . . . . . . . . . . . . . . . 23
2.12 Transformation nach der Hitzeschock-Methode (19) . . . . . . . . . . . . . 24
2.13 Plasmidpräparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.14 Bestimmung der Indigobildung durch Klone mit mutmaÿlicher SMO-Aktivität 24
2.14.1 Abschätzung der Indigobildung durch Augenschein . . . . . . . . . 25
2.14.2 Quanti zierung der Indigobildung mittels UV/Vis-Spektrophotometrie 25
2.14.3 Quanti zierung der Indigobildung aus Flüssigkulturen . . . . . . . . 26
3 Ergebnisse 27
3.1 Versuche der error prone PCR von StyA2B aus Rhodococcus opacus 1CP . 27
3.1.1 Isolation von Templat-DNA und Durchführung der error prone PCR 28
3.1.2 Screening von Transformanden auf Fähigkeit zur Indol-Oxidation . 29
3.1.3 Herstellung und Aktivitätsscreening von E. coli DH5ff pET_StyA2B 30
3.2 Versuche der error prone PCR von styA1/styA2B aus Rhodococcus opacus
1CP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.1 Durchführung der error prone PCR und Aktivitätsscreening von
StyA1/StyA2B in pBluescript KS(+) . . . . . . . . . . . . . . . . . 31
3.2.2 Durchführung des Aktivitätsscreening von StyA1/StyA2B in pET16bP 32
3.3 Fusionsproteine StyAL1B und StyAL2B aus Pseudomonas uorescens ST . 33
3.3.1 Optimierung der Zusammensetzung des LB-Mediums für das Aktivitätsscreenings
von pET_StyAL2B in E. coli BL21 nach einer Transformation
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3.2 Ein uss der Belüftung auf die Neigung von E. coli BL21 (pET_StyAL2B)
Kolonien zur Oxidation von Indol . . . . . . . . . . . . . . . . . . . 38
3.3.3 Bestimmung der Indigobildung mittels UV/Vis-Spektroskopie . . . 40
3.3.4 Zeitliche Entwicklung der Indigokonzentration einer Flüssigkultur
von E. coli BL21 (pET_StyAL2B) . . . . . . . . . . . . . . . . . . 42
3.3.5 Error prone PCR von pET_StyAL2B mit Gene Morph II EZ Clone
Kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.3.6 Error prone PCR nach der klassischen Methode mit pET_StyAL1B
und pET_StyAL2B . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4 Diskussion der Ergebnisse 49
4.1 Die error prone PCR als attraktive Methodik zur Optimierung von Styrol-
Monooxygenasen hinsichtlich katalytischer Eigenschaften . . . . . . . . . . 49
4.2 Der Aktivitätsnachweis als mutmaÿlich limitierender Schritt in der Modi-
zierung von StyA2B und StyA1/StyA2B mit Hilfe der error prone PCR . 51
4.3 Die künstlich fusionierten Styrol-Monooxygenasen StyAL2B und StyAL1B
erlauben ein Aktivitätsscreening auf Platte . . . . . . . . . . . . . . . . . . 53
4.4 Die Entwicklung einer Methodik zur Quanti zierung der spezi schen Indigobildung
eines Expressionsklons der Styrol-Monooxygenase StyAL2B . . . 58
4.5 Fehleranalyse zur error prone PCR . . . . . . . . . . . . . . . . . . . . . . 59
4.5.1 Fehler in der klassischen error prone PCR für pET_StyAL1B und
pET_StyAL2B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Literaturverzeichnis 65 / Styrene monooxygenases (SMOs) play an important role in the bacterial degradation of styrene. They epoxidize the hydrocarbon highly enantioselective to (S)-styrene oxide. Most of the styrene monooxygenases known so far were identified in Gram-negative microorganisms like pseudomonads. Rhodococcus opacus 1CP, a Gram-positive nocardioform actinobacterium, which uses styrene as energy and carbon source was recently found to possess a novel type of SMO, StyA2B. This protein represents a natural fusion between an FAD:NADH oxidoreductase (StyB) and a single monooxygenase subunit (StyA2) and might act in combination with another single oxygenase StyA1 in strain 1CP. Two artificial analogs to StyA2B, designated StyAL1B and StyAL2B, were recently prepared by a fusion of styA and styB of Pseudomonas fluorescens ST and both showed oxygenating
activity.
For StyA1/StyA2B as well as the artificial fusion proteins StyAL1B and StyAL2B, it was tried to enhance the specific oxygenation activity in order to support their biotechnological applicability. The method of error prone PCR was used for that purpose. In order to identify favorable modifications with increased catalytic activity from a high number of mutants, an easy and simple screening test is necessary. Therefore, it is reasonable to use the ability of SMOs to oxidize indole to the blue dye indigo. However, the expression of SMOs as soluble proteins is an important requirement for any activity screening. Attempts to modify the genes styA2B and styA1/styA2B by means of a commercial error prone PCR kit yielded 300 to 1,200 potential mutants. Unfortunately, none of the obtained colonies showed any indole-oxidizing activity and the formation of insoluble inclusion bodies was assumed to be a likely explanation.
In contrast to StyA2B and StyA1, recombinant expression of the artificial fused SMOs StyAL1B und StyAL2B should yield detectable amounts of active proteins. In fact, cultivation of clones expressing both types of proteins showed a blue coloration. Since the coloration of clones from one single solid medium evolved in a non-uniform manner, cultivation
conditions were varied in order to identify factors which promote a more uniform tendency for indole oxidation. Although a high NaCl concentration in the medium was shown to favor indole oxidation, the latter one seems to be influenced by additional physiological factors, hardly to control.
For the artificially fused proteins an error prone PCR was carried out, too. Although the initial step of mutagenic PCR was found to be successful, completing the vector system by a second ll-up PCR reaction failed. Alternative strategies like the usage of alternative DNA polymerases as well as a conventional cloning approach of various genes into a digested expression vector did not lead to detectable clones. The cultivation of identical clones on petri dishes provided no uniform tendency for indole oxidation and thus did not allow the reliable comparison of mutants in respect of their specific SMO activities. Cultivation of mutants in liquid medium should lead to more reproducible conditions and for that purpose a method was successfully established to quantify indigo formation and cell density.:Eidesstattliche Erklärung II
Danksagung III
Zusammenfassung IV
Abstract VI
Abbildungsverzeichnis XI
Tabellenverzeichnis XIII
Abkürzungsverzeichnis XIV
1 Einleitung 1
1.1 Styrol - ein Produkt der Industrie . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Styrol-Monooxygenasen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Abbauwege von Styrol . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 Struktur, Vorkommen und Eigenschaften klassischer Zweikomponenten
Styrol-Monooxygenasen . . . . . . . . . . . . . . . . . . . . 4
1.2.3 Das neuartige Styrol-Monooxygenase-System StyA1/StyA2B aus
Rhodococcus opacus 1CP . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.4 Künstlich verlinkte SMO aus Pseudomonas uorescens ST . . . . . 7
1.2.5 Biotechnologischer Einsatz von Styrol-Monooxygenasen . . . . . . . 8
1.3 Strategien des Protein-Engineering . . . . . . . . . . . . . . . . . . . . . . 9
1.3.1 Arbeitsmethoden zur Veränderung von DNA . . . . . . . . . . . . . 9
1.3.2 Error prone PCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4 Arbeitsziele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Material und Methoden 13
2.1 Bakterienstämme und Plasmide . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Kultivierungsmedien und -bedingungen . . . . . . . . . . . . . . . . . . . . 14
2.2.1 Kultivierungsmedien . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.2 Kultivierungstemperaturen . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 Polymerase-Kettenreaktion (PCR) . . . . . . . . . . . . . . . . . . . . . . 16
2.3.1 Primer und Primerdesign . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3.2 Standard-PCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Fehlerbehaftete Polymerase-Kettenreaktion (epPCR) . . . . . . . . . . . . 17
2.4.1 Synthese der mutagenen Megaprimer . . . . . . . . . . . . . . . . . 18
2.4.2 EZClone Reaktion . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.3 Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.4 Modi zierung des Protokolls des EZClone Reaktion Schrittes . . . . 20
2.5 Aufreinigung von PCR-Produkten aus der Lösung . . . . . . . . . . . . . . 20
2.6 TAE-Agarose-Gelelektrophorese . . . . . . . . . . . . . . . . . . . . . . . . 20
2.7 DNA-Extraktion aus Agarosegelen . . . . . . . . . . . . . . . . . . . . . . 21
2.8 Bestimmung der DNA-Konzentration . . . . . . . . . . . . . . . . . . . . . 21
2.9 Restriktionsverdau von DNA . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.10 Ligation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.11 Herstellung von kompetenten Zellen (E.coli DH5ff, E. coli BL21) . . . . . 23
2.11.1 Chemisch kompetente Zellen nach der CaCl2-Methode (42) . . . . . 23
2.11.2 TOP10 chemischkompetente Zellen . . . . . . . . . . . . . . . . . . 23
2.12 Transformation nach der Hitzeschock-Methode (19) . . . . . . . . . . . . . 24
2.13 Plasmidpräparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.14 Bestimmung der Indigobildung durch Klone mit mutmaÿlicher SMO-Aktivität 24
2.14.1 Abschätzung der Indigobildung durch Augenschein . . . . . . . . . 25
2.14.2 Quanti zierung der Indigobildung mittels UV/Vis-Spektrophotometrie 25
2.14.3 Quanti zierung der Indigobildung aus Flüssigkulturen . . . . . . . . 26
3 Ergebnisse 27
3.1 Versuche der error prone PCR von StyA2B aus Rhodococcus opacus 1CP . 27
3.1.1 Isolation von Templat-DNA und Durchführung der error prone PCR 28
3.1.2 Screening von Transformanden auf Fähigkeit zur Indol-Oxidation . 29
3.1.3 Herstellung und Aktivitätsscreening von E. coli DH5ff pET_StyA2B 30
3.2 Versuche der error prone PCR von styA1/styA2B aus Rhodococcus opacus
1CP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.1 Durchführung der error prone PCR und Aktivitätsscreening von
StyA1/StyA2B in pBluescript KS(+) . . . . . . . . . . . . . . . . . 31
3.2.2 Durchführung des Aktivitätsscreening von StyA1/StyA2B in pET16bP 32
3.3 Fusionsproteine StyAL1B und StyAL2B aus Pseudomonas uorescens ST . 33
3.3.1 Optimierung der Zusammensetzung des LB-Mediums für das Aktivitätsscreenings
von pET_StyAL2B in E. coli BL21 nach einer Transformation
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3.2 Ein uss der Belüftung auf die Neigung von E. coli BL21 (pET_StyAL2B)
Kolonien zur Oxidation von Indol . . . . . . . . . . . . . . . . . . . 38
3.3.3 Bestimmung der Indigobildung mittels UV/Vis-Spektroskopie . . . 40
3.3.4 Zeitliche Entwicklung der Indigokonzentration einer Flüssigkultur
von E. coli BL21 (pET_StyAL2B) . . . . . . . . . . . . . . . . . . 42
3.3.5 Error prone PCR von pET_StyAL2B mit Gene Morph II EZ Clone
Kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.3.6 Error prone PCR nach der klassischen Methode mit pET_StyAL1B
und pET_StyAL2B . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4 Diskussion der Ergebnisse 49
4.1 Die error prone PCR als attraktive Methodik zur Optimierung von Styrol-
Monooxygenasen hinsichtlich katalytischer Eigenschaften . . . . . . . . . . 49
4.2 Der Aktivitätsnachweis als mutmaÿlich limitierender Schritt in der Modi-
zierung von StyA2B und StyA1/StyA2B mit Hilfe der error prone PCR . 51
4.3 Die künstlich fusionierten Styrol-Monooxygenasen StyAL2B und StyAL1B
erlauben ein Aktivitätsscreening auf Platte . . . . . . . . . . . . . . . . . . 53
4.4 Die Entwicklung einer Methodik zur Quanti zierung der spezi schen Indigobildung
eines Expressionsklons der Styrol-Monooxygenase StyAL2B . . . 58
4.5 Fehleranalyse zur error prone PCR . . . . . . . . . . . . . . . . . . . . . . 59
4.5.1 Fehler in der klassischen error prone PCR für pET_StyAL1B und
pET_StyAL2B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Literaturverzeichnis 65
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Electrically conductive textile coatings with PEDOT:PSSÅkerfeldt, Maria January 2015 (has links)
In smart textiles, electrical conductivity is often required for several functions, especially contacting (electroding) and interconnecting. This thesis explores electrically conductive textile surfaces made by combining conventional textile coating methods with the intrinsically conductive polymer complex poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). PEDOT:PSS was used in textile coating formulations including polymer binder, ethylene glycol (EG) and rheology modifier. Shear viscometry was used to identify suitable viscosities of the formulations for each coating method. The coating methods were knife coating, pad coating and screen printing. The first part of the work studied the influence of composition of the coating formulation, the amount of coating and the film formation process on the surface resistivity and the surface appearance of knife-coated textiles. The electrical resistivity was largely affected by the amount of PEDOT:PSS in the coating and indicated percolation behaviour within the system. Addition of a high-boiling solvent, i.e. EG, decreased the surface resistivity with more than four orders of magnitude. Studies of tear strength and bending rigidity showed that textiles coated with formulations containing larger amounts of PEDOT:PSS and EG were softer, more ductile and stronger than those coated with formulations containing more binder. The coated textiles were found to be durable to abrasion and cyclic strain, as well as quite resilient to the harsh treatment of shear flexing. Washing increased the surface resistivity, but the samples remained conductive after five wash cycles. The second part of the work focused on using the coatings to transfer the voltage signal from piezoelectric textile fibres; the coatings were first applied using pad coating as the outer electrode on a woven sensor and then as screen-printed interconnections in a sensing glove based on stretchy, warp-knitted fabric. Sensor data from the glove was successfully used as input to a microcontroller running a robot gripper. These applications showed the viability of the concept and that the coatings could be made very flexible and integrated into the textile garment without substantial loss of the textile characteristics. The industrial feasibility of the approach was also verified through the variations of coating methods.
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Μελέτη αλληλεπιδράσεων ιόντων Cu2+ με συμπολυμερή του ακρυλικού οξέος σε υδατικό διάλυμα / Study of the interactions between Cu2 + ion with acrylic acid copolymers in aqueous mediaΤσοπελάκης, Φίλιππος 02 April 2014 (has links)
Στην εργασία αυτή προχωρήσαμε στη μελέτη της αλληλεπίδρασης των ιόντων δισθενούς χαλκού, Cu2+ με στατιστικά συμπολυμερή P(ANa-co-SSNa) του ακρυλικού οξέος, (ANa) με το στυρενοσουλφονικό οξύ (SSNa). Συντέθηκαν τα συμπολυμερή P(ANa50-co-SSNa) και P(AΝa80-co-SSNa) που περιέχουν 50 mol% και 80 mol% ακρυλικού οξέος αντίστοιχα. Τα συμπολυμερή αυτά χαρακτηρίστηκαν με φασματοσκοπία πυρηνικού μαγνητικού συντονισμού 1H NMR.
Προχωρήσαμε στην φυσικοχημική μελέτη της αλληλεπίδρασης ιόντων δισθενούς χαλκού, Cu2+, με τα συμπολυμερή P(ANa50-co-SSNa) και P(AΝa80-co-SSNa) χρησιμοποιώντας διάφορες τεχνικές όπως η θολομετρία, η ιξωδομετρία και η φασματοσκοπία UV-vis. Τα πειράματα πραγματοποιήθηκαν σε υδατικά διαλύματα, στα οποία χρησιμοποιήθηκε ως διαλύτης τρισαπιονισμένο νερό, H2O-3D. Για λόγους σύγκρισης μελετήθηκαν επίσης τα αντίστοιχα ομοπολυμερή των μονομερών που αποτελούν τα συμπολυμερή P(ANa-co-SSNa). Έτσι, πραγματοποιήθηκε φυσικοχημική μελέτη της αλληλεπίδρασης των ιόντων Cu2+ με το πολυ(ακρυλικό νάτριο), PANa, και το πολυ(στυρενοσουλφονικό νάτριο), PSSNa, αντίστοιχα.
Από την ιξωδομετρική μελέτη προέκυψε πως η εισαγωγή ιόντων χαλκού Cu2+ σε υδατικό διάλυμα πολυμερούς οδηγεί στην μείωση του ανηγμένου ιξώδους. Μάλιστα η μείωση αυτή είναι πιο δραστική καθώς αυξανεται η συγκέντρωση ιόντων Cu2+ στο διάλυμα. Αυτή η συμπεριφορά αποτελεί ένδειξη της συμπλοκοποίησης των ιόντων χαλκού, Cu2+, με τις ομάδες καρβοξυλίων του ακρυλικού οξέος (ΑΑ). Διαπιστώθηκε πως στα συμπολυμερή P(ANa-co-SSNa) τα Cu2+ συμπλοκοποιούνται με τα καρβοξύλια του ακρυλικού οξέος σε αναλογία ιόντων χαλκού προς ομάδες καρβοξυλίων ίση με 1:2.
Όσον αφορά στην μελέτη με UV-vis, ενώ στην περίπτωση του ομοπολυμερούς PSSNa δεν υπάρχει κάποια ιδιαίτερη αλληλεπίδραση τύπου συμπλόκου ένταξης μεταξύ του πολυμερούς και των ιόντων του Cu2+, στην περίπτωση του συμπολυμερούς Ρ(ΑNa50-co-SSNa), παρατηρήθηκε μετατόπιση του σήματος των ιόντων Cu2+ (από τα 800 στα 745 nm) παρουσία του συμπολυμερούς. Αυτό είναι χαρακτηριστικό του σχηματισμού συμπλόκου ένταξης μεταξύ των ιόντων του Cu2+ και των ομάδων COO- του συμπολυμερούς. / In the present work we studied the interaction of bivalent copper ions Cu2+ with random copolymers P(ANa-co-SSNa) of acrylic acid (ANa) and styrenesulfonic acid (SSNa). Two copolymers, P(ANa50-co-SSNa) and P(AΝa80-co-SSNa) with 50 mol% and 80 mol% in acrylic acid, respectively, were synthesized and characterized by neutron magnetic resonance spectroscopy, 1H NMR.
We proceeded in the physicochemical study of the interaction
of bivalent copper ions, Cu2+, with P(ANa50-co-SSNa) and P(AΝa80-co-SSNa) copolymers using techniques like turbidimetry, viscometry and UV-vis spectroscopy. The experiments were performed in aqueous media using 3D water, H2O-3D. For reasons of comparison the respective homopolymers of sodium polyacrylate, PANa, and poly(styrene sulfonate), PSSNa, were also studied.
From viscometry it was found that the introduction of copper ions in the polymer aqueous solutions leads to the decrease of the reduced viscosity. Moreover, this decrease is more pronounced as the concentration of Cu2+ increases in the solution. This behavior is indicative of the complexation between Cu2+ with the carboxylate groups of acrylic acid (ΑΑ). In the P(ANa-co-SSNa)/Cu2+ system, it was found that complexation occurs when the ratio of copper ions to carboxylates is equal to 1:2.
UV-vis spectroscopy showed that, while in the case of PSSNa homopolymer there is not strong interaction with Cu2+, in the case of the Ρ(ΑNa50-co-SSNa) copolymer, the introduction of the polymer lead to a shift of the maximum absorbance of Cu2+ (from 800 to 745 nm). This was due to the complexation of Cu2+ with the COO- groups of the copolymer.
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Dynamic modelling and optimization of polymerization processes in batch and semi-batch reactors : dynamic modelling and optimization of bulk polymerization of styrene, solution polymerization of MMA and emulsion copolymerization of styrene and MMA in batch and semi-batch reactors using control vector parameterization techniquesIbrahim, W. H. B. W. January 2011 (has links)
Dynamic modelling and optimization of three different processes namely (a) bulk polymerization of styrene, (b) solution polymerization of methyl methacrylate (MMA) and (c) emulsion copolymerization of Styrene and MMA in batch and semi-batch reactors are the focus of this work. In this work, models are presented as sets of differential-algebraic equations describing the process. Different optimization problems such as (a) maximum conversion (Xn), (b) maximum number average molecular weight (Mn) and (c) minimum time to achieve the desired polymer molecular properties (defined as pre-specified values of monomer conversion and number average molecular weight) are formulated. Reactor temperature, jacket temperature, initial initiator concentration, monomer feed rate, initiator feed rate and surfactant feed rate are used as optimization variables in the optimization formulations. The dynamic optimization problems were converted into nonlinear programming problem using the CVP techniques which were solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. The process model used for bulk polystyrene polymerization in batch reactors, using 2, 2 azobisisobutyronitrile catalyst (AIBN) as initiator was improved by including the gel and glass effects. The results obtained from this work when compared with the previous study by other researcher which disregarded the gel and glass effect in their study which show that the batch time operation are significantly reduced while the amount of the initial initiator concentration required increases. Also, the termination rate constant decreases as the concentration of the mixture increases, resulting rapid monomer conversion. The process model used for solution polymerization of methyl methacrylate (MMA) in batch reactors, using AIBN as the initiator and Toluene as the solvent was improved by including the free volume theory to calculate the initiator efficiency, f. The effects of different f was examined and compared with previous work which used a constant value of f 0.53. The results of these studies show that initiator efficiency, f is not constant but decreases with the increase of monomer conversion along the process. The determination of optimal control trajectories for emulsion copolymerization of Styrene and MMA with the objective of maximizing the number average molecular weight (Mn) and overall conversion (Xn) were carried out in batch and semi-batch reactors. The initiator used in this work is Persulfate K2S2O8 and the surfactant is Sodium Dodecyl Sulfate (SDS). Reduction of the pre-batch time increases the Mn but decreases the conversion (Xn). The sooner the addition of monomer into the reactor, the earlier the growth of the polymer chain leading to higher Mn. Besides that, Mn also can be increased by decreasing the initial initiator concentration (Ci0). Less oligomeric radicals will be produced with low Ci0, leading to reduced polymerization loci thus lowering the overall conversion. On the other hand, increases of reaction temperature (Tr) will decrease the Mn since transfer coefficient is increased at higher Tr leading to increase of the monomeric radicals resulting in an increase in termination reaction.
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Neue Wege in der Weißen BiotechnologieTischler, Dirk, Oelschlägel, Michel, Zimmerling, Juliane, Schlömann, Michael 20 October 2016 (has links) (PDF)
Mikroorganismen sind in der Lage, zahlreiche Xenobiotika abzubauen. Dazu nutzen sie unter aeroben Bedingungen oft einleitend Oxygenasen. Durch diese kann molekularer Luftsauerstoff aktiviert und auf organische Moleküle übertragen werden. Danach können die Verbindungen in den Metabolismus der Mikroorganismen eingeschleust und teils oder vollständig abgebaut werden. Am Beispiel des Styrols zeigen wir hier eine solche Abbauroute und wie wir diese biotechnologisch nutzen können, um interessante Verbindungen zu synthetisieren. Zielmoleküle der gesamten Enzymkaskade sind dabei diverse Phenylessigsäurederivate.
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Modelagem matemática e estudo experimental da copolimerização de estireno e butadieno em emulsão. / Mathematical modeling and experimental study of styrene - butadiene emulsion copolymerization.Pinelli Filho, Aluisio 08 May 2006 (has links)
Neste trabalho, estudos da copolimerização em emulsão de estireno e butadieno foram realizados em duas etapas. A primeira etapa consistiu na obtenção de um modelo matemático que representasse os processos em batelada e em semicontínuo através das principais variáveis do processo. Na segunda etapa, o efeito de diversas variáveis importantes ao processo foi avaliado, dentre elas: o tempo de adição dos reagentes, o tipo de alimentação empregado e a temperatura da reação. O modelo matemático se baseia em um trabalho previamente publicado que foi adaptado para simular o processo de copolimerização de estireno e butadieno em emulsão. Foram simulados processos em batelada e em semicontínuo. Em conjunto com os resultados experimentais, foi realizada a estimação de parâmetros não obtidos na literatura utilizando o método de Marquardt. As características do processo e as propriedades do polímero, tais como, conversão, diâmetro de partícula, taxa de polimerização e pressão interna do reator também foram obtidas, fornecendo condições para otimização e avaliação do processo de polimerização em batelada e em semicontínuo. Adicionalmente, também foi proposto um modelo de equilíbrio líquido-vapor dos monômeros. Os ensaios experimentais foram realizados em reator encamisado semicontínuo de mistura com 3 litros, nos quais foram utilizados persulfato de sódio como iniciador, lauril sulfato de sódio como emulsificante e tercdodecil mercaptana como agente de transferência de cadeia. Foram estudados os efeitos da temperatura, do tipo e do tempo de alimentação utilizada. A velocidade de polimerização, os diâmetros médios de partículas, o teor de monômero residual, o teor de insolúveis e o teor de resíduos foram avaliados. A cromatografia gasosa foi aplicada com sucesso em análises de látex e monômeros com finalidades diversas, destacando-se a obtenção de coeficientes de atividade necessários ao modelo de equilíbrio líquido-vapor, análise da concentração de monômeros ao longo da reação e análise da concentração de monômero residual. / In this work, studies of the styrene butadiene emulsion copolymerization had been performed in two stages. The first stage composed of a mathematical model that represented the batch and semi continuous process. In the second stage, the effects of diverse process variables were evaluated, among them: the time of addition of the reagents, feeding type and temperature reaction. The mathematical model was based on previously published work that it was adapted to simulate the styrene butadiene emulsion copolymerization process. Batch and semi continuous processes were simulated. In assembly with the experimental results, Marquardt method was applied to estimate some parameters that wasnt found in literature. The variable process and the properties of polymer, such as, conversion, particle diameter, rate of polymerization and pressure of the reactor had been also simulated to batch and semicontinous process. A liquid-vapor balance of monomers model was proposed. The experimental stage had been carried through in a semi continuous stirring jacket tank reactor with 3 liters. Sodium persulfate as initiating, sodium lauryl sulfate as surfactant and Tert dodecyl mercaptan as chain transference agent had been used. The effect of temperature, type and time feeding had been studied. Polymerization rate, particles diameter, residual monomer had been evaluated. The gaseous chromatography was successfully applied in analyses of latex with diverse purposes: activity coefficient estimation, adjustment of liquid-vapor model, analysis of residual monomer of the reaction and volatiles organic components concentration in final latex.
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Avaliação de algumas propriedades de concretos estruturais com agregados graúdos reciclados modificados com látex estireno-butadieno / Evaluating of coarse recycled aggregates and the use of styrene-butadiene latex in the concrete constitution of medium resistance concrete structuresBallista, Luiz Paulo Zuppani 31 March 2003 (has links)
Esta pesquisa objetiva avaliar o emprego de agregados graúdos reciclados (produzidos a partir do entulho de construção e demolição) e o emprego do látex estireno-butadieno (polímero sintético) nas propriedades de concretos estruturais de média resistência. Todos os estudos são conduzidos comparando-se as propriedades de concretos com agregados naturais sem adição de látex, e de concretos com agregados graúdos reciclados com e sem adição de látex. Na primeira fase da pesquisa, são avaliadas propriedades físicas e mecânicas destes concretos. São analisados três traços (com diferentes consumos de cimento) modificados com quatro percentagens de látex e submetidos a quatro formas de cura. Os resultados da primeira fase formam a base para a segunda fase da pesquisa, na qual apenas um dos traços contendo uma determinada porcentagem de látex e sob uma única forma de cura é submetido a ensaios em célula de corrosão acelerada e aderência aço-concreto. Como resultado principal, tem-se que o emprego conjunto de agregados graúdos reciclados e látex estireno-butadieno fornece concretos com resistência mecânica equivalente aos concretos contendo agregados naturais e com desempenho em ambientes agressivos e aderência aço-concreto também semelhantes. Conclui-se, portanto, pela viabilidade do emprego destes concretos como concreto estrutural armado no que tange às propriedades avaliadas. / This research aims at evaluating the use of coarse recycled aggregates (produced from construction and demolition debris) and the use of styrene-butadiene latex (synthetic polymer) in the concrete constitution of medium resistance concrete structures. All studies are carried out comparing the concrete properties with natural aggregates without latex, and concrete with coarse recycled aggregates with or without latex. In the first stage of the research, physical and mechanical properties of these concretes are evaluated (with different cement contents) modified with four percent of latex and submitted to four cure condition. The results of the first stage produce the base for the second stage of the research, where only one of the features containing a determinate percentage of latex and under a sole form of cure condition it is submitted to tests in accelerated corrosive cell and steel-concrete adherence. As a main result, it is believed that the joint usage of coarse recycled aggregates and styrene-butadiene latex provides mechanical resistant concrete equivalent to concrete containing natural aggregates with a similar performance in aggressive environments and with steel-concrete adherence. Due to the its employment feasibility, one can conclude that this concrete is structurally armed in as far as its properties were evaluated.
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Almofada de apoio de compósito de cimento para ligações em concreto pré-moldado / Bearing pad of cement composite for connections in precast concreteSiqueira, Gustavo Henrique 30 March 2007 (has links)
Esta pesquisa apresenta um estudo de uma argamassa modificada para uso como elemento de ligação entre elementos de concreto pré-moldado. A argamassa utilizada nesta pesquisa é obtida pela introdução de látex estireno-butadieno (SB) e fibras de polipropileno a uma argamassa de cimento e areia. Estas adições modificam suas propriedades mecânicas, proporcionando o aumento da deformabilidade por diminuição do módulo de elasticidade do compósito, conferindo-lhe características favoráveis ao uso como elemento de apoio para elementos pré-moldados de concreto. Foram realizados ensaios de caracterização do compósito por meio da obtenção das resistências à compressão e à tração e, do módulo de elasticidade para corpos-de-prova cilíndricos com 50 mm de diâmetro com 100 mm de altura. Ensaios de capacidade de deformação, capacidade de rotação e capacidade de acomodação de imperfeições e distribuição das tensões foram realizados em almofadas de 150 mm x 150 mm com espessura de 10 mm. Os resultados mostraram que o material possui boa capacidade de se deformar em níveis de tensão da ordem de 10 a 20 MPa mantendo sua resiliência. Valores de rotações entre 0,01 e 0,02 rad foram obtidos nos ensaios, sendo estas maiores que os valores necessários para a maioria dos casos convencionais de projeto. Na acomodação e distribuição das tensões, a presença das almofadas promoveu uma melhora de 25% no desempenho de ligações submetidas à compressão uniforme, com rugosidades de 1,0 mm. / This research presents a study of a mortar modified to use as bearing pad between precast concrete elements. The mortar used in this research is achieved by the introduction of styrene-butadiene latex (SB) and polypropylene fibers into a cement mortar and sand, modifying their mechanical properties, as increase of the potential deformation by decrease of the composite modulus of elasticity, providing favorable characteristics to the use as bearing pad for precast concrete elements. Cylindrical samples of 50 mm of diameter with height of 100 mm were molded and tested to determination the compressive and the tensile strength and also the modulus of elasticity of the composite. Compression tests with cushions of 150 mm x 150 mm of base with thickness of 10 mm were done to determinate the deformation capacity, rotation capacity and capacity of accommodation of imperfections and distribution of the stresses between precast elements. The results showed that the material has a capacity to deform in levels of tension from 10 to 20 MPa maintaining his resilience. Values of rotations among 0,01 and 0,02 rad were obtained, being these larger ones than the necessary values for most of the conventional cases of project. In the accommodation and distribution of the stresses, the presence of the bearing pad promoted an improvement of 25% in the strength of connections subject to uniform compressive stresses, with surface irregularities of 1,0 mm.
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Modificação de poli(fluoreto de vinilideno) induzida por radiação gama para aplicação como compósito ionomérico de metal-polímero / Poly(vinylidene fluoride) modification induced by gamma irradiation for application as ionic polymer-metal compositeFerreira, Henrique Perez 25 July 2011 (has links)
Foi estudada a enxertia de estireno induzida por radiação gama em filmes de poli(fluoreto de vinilideno) (PVDF) com espessura de 0,125 mm com doses entre 1 e 100 kGy em presença de soluções de estireno/N,Ndimetilformamida (DMF) (1:1, v/v) e estireno/tolueno (1:1, v/v) com taxa de dose de 5 kGy.h-1 por meio do método simultâneo de irradiação sob atmosfera de nitrogênio e em temperatura ambiente, usando raios gama de uma fonte de Co- 60. Depois de enxertados, os polímeros foram sulfonados em soluções de ácido clorossulfônico/1,2-dicloroetano (2 e 10 %). Os filmes foram caracterizados antes e depois de cada modificação com o cálculo do Grau de enxertia, (DOG), espectrometria no infravermelho (FT-IR), microscopia eletrônica de varredura (MEV), calorimetria exploratória diferencial (DSC) e termogravimetria (TG/DTG). Os resultados do grau de enxertia mostraram que a enxertia aumenta com o aumento da dose e varia enormemente de acordo com o solvente utilizado, com enxertias cerca de 20 vezes maiores quando do uso da DMF em relação ao do tolueno. Foi possível confirmar a enxertia do estireno por FT-IR graças ao aparecimento de novos picos característicos e por TG/DTG e DSC por meio das alterações do comportamento térmico dos materiais enxertados/sulfonados. Os materiais sulfonados ainda foram caracterizados por suas capacidades de troca iônica (IEC), que mostraram que tanto os aumentos do grau de enxertia quanto os da concentração do ácido clorossulfônico aumentam o IEC. Os resultados mostraram que é possível obter materiais com capacidades de troca iônica com possibilidade de aplicação como compósitos ionoméricos de metal-polímero. / Gamma-radiation-induced grafting of styrene into poly(vinylidene fluoride) (PVDF) films with 0.125 mm thickness at doses from 1 to 100 kGy in the presence of a styrene/N,N- dimethylformamide (DMF) solution (1:1, v/v) and styrene/toluene (1:1, v/v) at dose rate of 5 kGy h-1 was carried out by simultaneous method under nitrogen atmosphere at room temperature, using gamma rays from a Co-60. After grafting reactions, the polymer was then sulfonated in chlorosulfonic acid/1,2-dichloroethane (2 and 10%) for 3 hours. The films were characterized before and after modification by calculating the degree of grafting (DOG), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). DOG results show that grafting increases with dose, and varies enormously depending on the solvent used, with DOGs about 20 times greater in DMF than in toluene. It was possible to confirm the grafting of styrene by FT-IR due to the appearance of the new characteristic peaks and by the TG and DSC which exhibited changes in the thermal behavior of the grafted/sulfonated material. Sulfonated material was also characterized by ion exchange capacity (IEC) showed that both DOG and sulfonic acid concentration increase IEC values. Results showed that it is possible to obtain materials with ion exchange capacity of possible application as ionic polymer-metal composites.
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Caracterização da sílica amorfa extraída da casca de arroz obtida por pré-hidrólise ácida e calcinação, e sua aplicação em borracha de estireno-butadieno (SBR) / Characterization of amorphous rice husk silica obtained by acidic prehydrolysis and calcination, and its application in styrene-butadiene rubber (SBR)Budemberg, Eduardo Roque 14 June 2013 (has links)
O crescimento dos países em desenvolvimento aumentará em várias vezes o consumo de energia, materiais e alimentos. Para suprir essa demanda é necessário o aproveitamento racional dos resíduos gerados por processos industriais, agrícolas e lixo urbano, transformando-os em energia economicamente competitiva com as outras formas de energia, e em materiais com propriedades otimizadas. O objetivo do presente trabalho foi comparar o comportamento da sílica da casca de arroz obtida por pré-hidrólise ácida seguida de calcinação controlada (Sil-PH) com sílicas de casca de arroz comerciais obtidas simplesmente pela queima da casca (Sil-B e Sil-C) e com a sílica comercial obtida da areia quartzítica (Sil-Z), como carga de reforço em borracha de estireno-butadieno (SBR), que é a mais usada na indústria de fabricação de pneus. Estudos foram conduzidos em SBR 1502, preparados conforme norma ASTM 3191-2010. Foram adicionadas à borracha as sílicas em concentrações de 0, 10, 20 e 40 ppcb. Foram conduzidos testes físicos, químicos, mecânicos, reométricos, dinâmico-mecânicos e análise térmica, bem como ensaios de inchamento dos corpos de prova em toluol e análise microestrutural das sílicas e dos compostos por microscopia eletrônica de varredura, com o objetivo de determinar a natureza do reforço. O número de ligações cruzadas foi avaliado e a energia de formação dessas ligações foi calculada. A relação entre as metodologias de cálculo da densidade de ligações cruzadas foi também avaliada, obtendo a caracterização desse tipo de carga de reforço não somente por correlações mecânicas mas também pela energia de formação das ligações. Os resultados mostraram que quanto maior a adição de sílica, maior é sua interação com a borracha. Dentre as sílicas adicionadas, Sil-Z alcançou os maiores valores de propriedades mecânicas dos compostos, e Sil-PH mostrou os melhores resultados dentre as sílicas de casca de arroz. Por avaliação por inchamento em toluol (teste estático) e por testes de tração e testes dinâmicos foi possível afirmar que as densidades de ligações cruzadas estão correlacionadas, Usando os resultados de reometria e as equações de Arrhenius estimou-se uma energia média de ligação, concluindo que esta corresponde a uma ligação do tipo covalente. Pelos valores de tan ? confirmou-se que os compostos com Sil-PH têm maior aderência no chão molhado do que aqueles com Sil-Z. A sílica nos compostos tende a diminuir a temperatura de transição vítrea. Os resultados da análise térmica mostraram elevada estabilidade térmica dos compostos com Sil-PH e Sil-Z. A falta de cominuição adequada da Sil-PH ocasionou uma dispersão irregular da sílica na SBR, uma molhabilidade parcial da sílica pela borracha e pelo agente de acoplamento, com consequente aparecimento de falhas na estrutura do composto. Por esse motivo as propriedades mecânicas dos compostos com Sil-PH foram inferiores às dos compostos com Sil-Z. / Developing countries are increasing by several times their consumption of energy, materials, and food. To attend their demand it is necessary to rationally reuse industrial, agricultural, and municipal solid waste residues, transforming them into economically competitive energy and materials with optimized properties. The objective of this work was to compare the behavior of a rice husk silica obtained by acidic prehydrolysis and controlled calcination (Sil-PH) with commercial amorphous silicas obtained from quartzite sand (Sil-Z) and from simply burned rice husks (Sil-B and Sil-C), as reinforcing filler in styrene-butadiene rubber (SBR) composites, which is the most used rubber in the tire manufacture industry. Studies were conducted on SBR 1502 rubber according to ASTM 3191-2010 in which amorphous silicas obtained from rice husk and quartzite silica were added at concentrations of 0, 10, 20, and 40 phr. Physical, chemical, mechanical, rheometric, dynamic-mechanical tests, thermal analysis, swelling studies in toluol and scanning electron microscopy of the silicas and composite specimens were made with objective to determine the nature of reinforcement. The number of crosslinks was evaluated and the energy of formation of these bonds calculated. The correlation between the methodologies of calculation of crosslink density was also evaluated, getting the characterization of this type of reinforcing filler not only by mechanical correlations but also by the energy of their formation. The results showed that the higher the content of added silica, the greater the interaction with rubber. According to the mechanical properties values Sil-Z achieved the highest properties values but Sil-PH showed better results compared to the other types of rice husk silicas. By evaluation by swelling in toluene (static), tensile tests and dynamic tests it was possible to affirm that the crosslink densities are correlated. By using the rheometry results and the Arrhenius equations the average bound was estimated to be of a covalent type. The silica in the compounds tends to lower the values of the glass transition temperature. The evaluation of tan ? showed that Sil-PH has more stickiness on the wet floor, which is an important property to tire application. Due to the lack of appropriate grinding of the Sil-PH the dispersion of the silica on SBR was irregular; partial wetting of the silica particles by rubber and silane had also occurred. Those facts had caused failures on the compound structural integrity, with a consequent lowering of the mechanical property values as compared to the compounds with Sil-Z addition.
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