Title : Synthesis of macrodisperse silica as a filler for rubber technical goods
In this work m acrodisperse silica was synthesized by the hydrolysis of diluted liquid glass (≈15w.% of SiO2, molar SiO2/Na2O≈3.0) with 1N H2SO4. The liquid glass was added to the solution of sulfuric acid while continuous mixing until the pH of the reaction mixture achieved 3±0.2. Then the synthesized gel was washed with distilled water, dried at 100°C and milled. A part of the synthesized silica gel was modified. For this purpose, the silica gel was mixed with 0.6N CH3COOH and held in these conditions for 3 days. The determination of particle size distribution was defined via the laser diffraction method using a laser particle sizer “Analysette 22” (Fritsch GmbH, Germany).
According to the obtained results, the differential curve of the particle size of the modified and unmodified silica gel corresponds to the normal distribution along a bell curve. The main (about 75%) size of the particles of the unmodified silica gel ranges from 14 to 70 μm. The content of the particles with the size of less than 14 μm is about 15% and the content of the particles with the size of more than 70 μm is around 10%. Modifying the silica gel using CH3COOH allowed us to obtain a sample with a narrower particle size distribution. In accordance with the results of the laser diffraction method about 75% of the particles correspond to the size 15–60 μm. The content of the particles with the size of less than 15 μm is about 15% and the particles with the size of more than 60 μm – 10%. This modifying influence of acetic acid can be caused by dispersing effect of the CH3COOH on the macrostructure of the silica gel when the decreasing of the size of globules occurs. It is shown that synthesized macrodisperse silica gel can be used as a filler for rubber materials.
Audience Take Away:
- The found relation between the dispersity of silica gels and the conditions of their synthesis and modifying can be used in physical, colloidal and applied chemistry. This knowledge is also of interest for technology of rubber technical goods.
- The results of the work have a practical importance and can be used in the production of rubber technical goods.
- The obtained knowledge can be used in teaching physical and colloidal chemistry.