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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of catalysts on the curing of acetylene-terminated monomers

Overend, Andrew Stuart January 1990 (has links)
No description available.
2

Rheological studies of non-aqueous poly methyl methacrylate dispersions stabilised using graft copolymer steric stabilisers

Savage, Matthew John January 1998 (has links)
Steric stabilisers were synthesised via the copolymerisation of styrene with acrylic macromonomers. The macromonomers were prepared by end capping reactions of poly 2-ethyl hexyl acrylate (PEHA) prepolymer with vinyl containing species. Preliminary reaction routes proceeded via the use of oxalyl chloride to create an acyl chloride intermediate followed by end capping with hydroxy ethyl methacrylate. This process was found to be inefficient due to the moisture sensitivity of the acyl chloride. The second route involved the direct end capping of the PEHA pre-polymer with glycidyl methacrylate (GMA). Macromonomer conversion levels were improved for the GMA route via the use of high temperatures and tertiary amine catalysts. An optimum set of conditions was achieved using 1.4 diazabicyclo [2.2.2.] octane as the catalyst and a reaction temperature of 160 QC. Non aqueous dispersion polymerisations of methyl methacrylate were performed. The factors affecting particle size in both single stage and twin stage polymerisation schemes were studied. Increases in the particle sizes of these dispersions were observed with increases in the total monomer concentration and also with decreases in the total stabiliser concentration. Increases in the particle size could also be achieved by increasing the proportion of the total monomer in the seed stage of the twin stage reaction and also by decreasing the proportion of the total stabiliser in the seed stage. The importance of the role of the seed upon the final particle size was firmly established. The rheology of these non aqueous dispersions was studied over a range of concentrations and under increasing shear stresses. At Iow and intennediate volume fractions the dispersions were observed to be predominantly Newtonian. Non-Newtonian behaviour was only observed at the extremes of the shear stress ranges studied. At high volume fractions of the dispersions non-Newtonian behaviour was observed over the range of shear stresses studied. Maximum volume fractions (~m) were calculated for these dispersions using the Kreiger-Dougherty equation. When these dispersions were blended in size ratios of 2:1 it was observed that 4 > m could be increased due to improved particle packing efficiency.
3

Structural Battery Electrolytes / Strukturella Batteri-Elektrolyter

Öberg, Pernilla, Halvarsson, Amanda, Rune, Julia, Bjerkensjö, Max January 2021 (has links)
Strukturella batterier är multifunktionella; de tillhandahåller lagring av elektrokemisk energi samtidigt som de bidrar med en lastbärande funktion. Tillsammans möjliggör detta att batteriet kan integreras i karossen hos ett elektriskt fordon eller apparat. Denna multifunktionalitet möjliggör således en avsevärd reducering i fordonets vikt. Kompositmaterialet är förstärkt av kolfiberelektroder, innesluten i en elektrolytstruktur. För att förverkliga detta koncept måste batteriets elektrolyt kunna motstå mekanisk belastning, samtidigt som den transporterar joner mellan batteriets elektroder. Denna studie syftar till att bygga vidare på konceptet av fas-separerade polymerelektrolyter, skapade från polymerisationsinducerad fasseparation via termisk härdning, vilket är en teknik utvecklad av Schneider et al. och Ihrner et al. Vidare undersöks effekten av att dels använda en elektrolytlösning baserad på EC:PC, men även att inkorporera tioler till polymernätverket. Tvärbindningsmolekylerna som användes i denna studie inkluderade trimetylolpropan tris(3-merkaptopropionat) (3TMP), pentaerythritol tetrakis(3-merkaptopropionat) (4PER), och dipentaerythritol hexakis-(3-merkaptopropionat) (6DPER). Dessa skiljer sig i antal funktionella tiolgrupper. Konduktivitet, termo-mekanisk prestanda och strukturberoende egenskaper undersöktes genom tre laborativa faser. Den första fasen behandlade inverkan på elektrolytsystemet av ändrat lösningsmedel, tiol-funktionalitet samt tiolgruppförhållandet gentemot allyl gruppen på den primära monomeren. Sampolymeren innehållandes 6DPER uppvisade bäst multifunktionalitet, varpå denna utvecklades vidare i fas två där en optimal sammansättning fastställdes som bestod utav 45 viktprocent jonlösning. I den slutliga fasen konstruerades en halv-cell baserat på den tidigare optimerade elektrolytkompositionen; den uppmätta kapaciteten visar tydlig förbättring jämfört med tidigare forskning. Resultatet som erhölls i denna studie bidrar till förståendet av strukturella batteri-elektrolyter samt den forskning som en dag kan komma att förverkliga strukturella batterier och dess tillämpningskrav. / Structural batteries are multifunctional; providing electrochemical energy storage synergistically with a load-bearing function that enables their integration into the body panels of electric devices and vehicles. Thus, massless energy can be achieved. As a composite material, it is composed of reinforcing carbon fibre electrodes embedded in an electrolyte matrix. To realize this concept, the electrolyte must simultaneously transfer mechanical load and transport ions between electrodes. The following study builds on a phase-separated polymer electrolyte, created using polymerization-induced phase separation via thermal curing, formulated by Schneider et al. and Ihrner et al.. The impact of the incorporation of thiols for copolymerization and as cross-linking agents for the polymer network was researched along with use of an EC:PC-based solvent. The three thiols studied were: trimethylolpropane tris(3-mercaptopropionate) (3TMP), pentaerythritol tetrakis(3-mercaptopropionate) (4PER), and dipentaerythritol hexakis-(3-mercaptopropionate) (6DPER). These differed in regard to the amount of thiol functional groups present. Ionic conductivity, thermo-mechanical performance and structure-property relationships were studied across 3 laboratory phases. The first phase concerned the effect of thiol-functionality, the thiol functional group ratio relative to the allyl group present in the primary monomer, and the solvent interaction. 6DPER was concluded to be the most promising cross-linking agent. During the second phase, the effect of electrolyte content was evaluated with an optimum of 45 weight% determined. The third phase concluded the study, wherein a half-cell was assembled with the optimized electrolyte formulation showing improved capacity relative to previous studies. The results developed here contribute to the understanding of structural battery electrolyte systems and their continued research to meet application demands.

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