Functional nanomaterials on the basis of inorganic oxides and polysaccharides for electrorheology

About the group:

The problems of investigation:

Electrorheologic liquids are the so called “smart materials”, their rheologic properties (viscosity, yield point, shear modulus, etc.) being able to vary under external electric field. Electrorheologic liquids are colloidal systems and dispersions with solid phase particles size in the range of several nanometers to dozens of micrometers in dielectric liquids. Since electrorheologic liquids can reversibly change their properties under external electric field, transforming from fluid to viscoplastic state in a few milliseconds, they can be used as an actuating medium of electrically triggered transfer mechanisms (absorbers, clutches, claws, valves) in different spheres of modern engineering and industry.
 
Current state:
 
The laboratory works at electrorheologic effect peculiarities in electrorheologic liquids, synthesized on the basis of various components of dispersed phase. The objects under investigation are:   
 
Individual substances such as silicon dioxide, titanium, barium and strontium titanates, starch, cellulose, carboxymethylcellulose, activated by molecular activators: water, amines. 
 
Hybrid organic-inorganic nanocomposites, formed according to sol – gel technique, the bond being between inorganic and organic components. Among them the following systems: silicon dioxide - polypropylene glycol, titanium dioxide - polypropylene glycol, titanium dioxide - hydroxypropyl cellulose. 
 
Mezo-structured mezo-porous materials, synthesized on the templates of micelles, formed by surface-active molecules, such as stearic acid, dodecylamine and polymer surfactants, the shell forming components being the hydrolysis products of titanium, silicon and aluminium alcoholates. 
 
Superdispersed structures of the “inorganic core – organic shell” type, being  superdispersed inorganic oxides particles or metal particles covered by oxide film encapsulated into organic shells of polymer and molecular nature 
 
Because of the wide range of objects under investigation the above mentioned materials are synthesized in the laboratory with the application of sol – gel technique.
 
Equipment and techinques:
 
  • Electrorheoviscosimeter, constructed on the basis of rheometer Rheotest and Brookfield, 
  • Setting for the testing of physico-mechanical properties of electrorheologic liquids on stretching under the electric fields of different intensity,  
  • Solubility microcalorimeters, 
  • X-ray phase analysis, 
  • Infrared spectroscopy, 
  • Electron  microscopy, 
  • Setting for colloidal systems dielectric properties measurements, 
  • Equipment for the sol – gel synthesis under ultrasound fields. 
 

Electron  photomicrography  of  mezo-porous silicon dioxide. The surface area of the sample is 640 m2/g (enlargement of 20000 times).

Electron  photomicrography  of  mezo-porous silicon dioxide. The surface area of the sample is more than 800 m2/g (enlargement of  16000 times).

 

 
Electrorheologic liquids stretching test
The curves of electrorheologic liquids cyclic stretching test

The curves of electrorheologic liquids stretching under electric field

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The curves of electrorheologic liquids compression under electric field

 

Laboratory facilities

Photo 1. The setting for the test electrorheologic liquids physico-mechanical properties under electric fields (stretching – compressing). 
Photo 2. The setting for the dispersions dielectric properties measurements.
Photo 3. Electrorheoviscosimeter, constructed on the basis of rotation viscosimeter РН-1 rheotest.
Photo 4. The Brookfield viscosimeter.