Silylation of Organoclay (Cloisite 30B) with trifunctional 3-(trimethoxysilyl)propyl methacrylate

The silylation reaction as a surface modification method of clay minerals plays a key role in determination of their application as fillers for polymeric materials. This reaction uses alkoxysilanes and exploits the OH reactive sites of the montmorillonite structure. Grafting of commercially available organoclay (Cloisite 30B) platelets with trifunctional 3- (trimethoxysilyl)propyl methacrylate (MPS) as a coupling agent has been reported in the present work. The effect of different parameters such as the amount of the silylating reagent, reaction time and temperature on the properties of modified organoclay was investigated using Taguchi experimental design method. Qualitative evidence of the presence of chemically attached silane molecules and its effect on d-spacing of the clay were confirmed by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. A slight increase in basal spacing of Cloisite 30B was observed after MPS treatment, which was attributed to the grafting reaction between the silane groups of MPS and the hydroxyl groups on the edge of Cloisite 30B. Furthermore, grafted amount and grafting yield were determined by thermogravimetric analysis (TGA). The thermograms exhibited three main decomposition regions. The region between 200 and 600 °C, which corresponds to the thermal decomposition of the organic molecules, was considered for quantitative determination of the silane coverage. At the optimum conditions, about 30% weight loss was observed in the thermogram of MPS/30B in the temperature range of 200-600 °C because of the combineddecomposition of ammonium ions and organosilanes. The obtained results showed that the initial trifunctional silane concentration and reaction time had a significant effect on the grafting efficiency of the final products whereas the reaction temperature (up to 45 °C) exhibited nearly no effect on the grafting of trifunctional silylating reagent.

کلیدواژه ها:

Cloisite 30B ، 3-(trimethoxysilyl)propyl methacrylate ، grafting ، experimental design