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## Testing the impact of ultrasounds in process of silica deagglomeration in water – organic systems

### Miranda Milena Tomasik

#### Abstract

The area of scientist interest are shear thickening fluids, which are based on colloidal silica [1]. In this type of liquid, silica is the solid phase of the suspension. To a suspension of the silica to have good properties, must be examine their rheological features. The obstacle which is facing researchers is disadvantageous agglomeration of its particles [2]. One way of dealing with with the process of agglomeration is ultrasonic breaking the agglomerates. Used for this purpose ultrasound washers. The effectiveness of an ultrasonic disintegration tested by the method of dynamic light scattering (DLS). It allows to obtain information on the average particle size of the silica. The aim of this study was to find the right concentration of silica suspension in water – polyethylene glycol system, or in an aqueous system. The next task was to determine the optimal time and frequency, enabling an effective deagglomeration of silica particles. The final objective was to compare the tested silicas differing in average particle size and choose this with better characteristics which have a direct impact on the formation of shear thickening fluids [3]. Five samples with the suspension were prepared. The solid phase was a colloidal silica having two average particle sizes. In the case of the first four samples average particle size of colloidal silica was in the range 200 - 300 nm. The diameter of the silica used in the last - fifth sample was 7 nm. The continuous phase in the system was polyethylene glycol having a molecular weight of 400 g / mol (PEG 400) and water in various proportions. Proportions of scattering medium used in the remaining four suspensions were sequentially: 1. 50% water / 50% polyethylene glycol (PEG400) 2. 10% water / 90% polyethylene glycol (PEG400) 3. 5% water / 95% polyethylene glycol (PEG400) 4. 5% water / 95% polyethylene glycol (PEG400) 5. 100% water Another scattering medium used in the case of the last sample was water. The next step was subjecting the suspension to ultrasound at different frequencies with a ultrasonic washer ULTRON. One of the used frequency was 21.5 kHz and the other 35 kHz. After the expiry of the relevant time needed for the sonication process samples were taken. The last stage of this study was to analyze samples with silica using analyzer Zetasizer Nano-ZS. The aim of this study was to determine how the average particle size of the solid phase changes relative to the pre-sonication process. In the case of using water as a dispersing phase, the agglomeration process occurred in a very small extent. The use of polyethylene glycol having average molecular weight 400 g / mol with water led to the formation of agglomerates of colloidal silica. The optimal concentration of the suspension, so that an efficient way possible was deagglomerated was the proportion of water and polyethylene glycol (PEG400) amounting to 50:50. The particle size after the deagglomeration then reached a minimum value. Colloidal silica having a particle diameter 7 nm were created in the same phase diffusion agglomerates of approximate size silica at 200 - 300 nm. For the testing samples the optimum time to deagglomerating process ran as effectively as possible was 120 minutes. For sample IV and V longer duration of action of ultrasound worked adversely affect the process of deagglomeration of the silica. The effect was to increase the average size of the particles. Better results can be observed in the case of sample V. The applied frequency was 35 kHz. However, this effect could affect another type of silica used. It had a smaller diameter, so could more easily undergo deagglomeration. The difference in concentrations did not alter depending on the charts. It is not, however, explored how the results would influence a greater concentration.
Diploma type
Engineer's / Bachelor of Science
Diploma type
Engineer's thesis
Author
Miranda Milena Tomasik (FC) Miranda Milena Tomasik,, Faculty of Chemistry (FC)
Title in Polish
Supervisor
Mariusz Tryznowski (FC/CPCT) Mariusz Tryznowski,, Chair Of Polymer Chemistry And Technology (FC/CPCT)Faculty of Chemistry (FC)
Certifying unit
Faculty of Chemistry (FC)
Affiliation unit
Chair Of Polymer Chemistry And Technology (FC/CPCT)
Study subject / specialization
, Technologia Chemiczna
Language
(pl) Polish
Status
Finished
Defense Date
22-01-2016
Issue date (year)
2016
Reviewers
Michał Młotek (FC/CChT) Michał Młotek,, Chair of Chemical Technology (FC/CChT)Faculty of Chemistry (FC) Mariusz Tryznowski (FC/CPCT) Mariusz Tryznowski,, Chair Of Polymer Chemistry And Technology (FC/CPCT)Faculty of Chemistry (FC)
Keywords in Polish
krzemionka koloidalna, aglomeraty, ciecze dylatancyjne, DLS, dynamiczne rozpraszanie światła, deaglomeracja, sonikacja, ULTRON, Zetasizer NANO-ZS, glikol polietylenowy
Keywords in English
fumed silica, agglomerates, shear thickening fluids, DLS, dynamic light scattering, deagglomeration, sonication, ULTRON, Zetasizer NANO-ZS, polyethylene glycol
Abstract in Polish
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Miranda_Tomasik_praca_inzynierska.pdf
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Identyfikator pracy APD: 8423

Uniform Resource Identifier
https://repo.pw.edu.pl/info/bachelor/WUTf193ee2cb2af4ccba77577ae9c7cff89/
URN
urn:pw-repo:WUTf193ee2cb2af4ccba77577ae9c7cff89

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