Single particle contact versus particle packing behavior: model based analysis of chemically modified glass particles

Smooth spherical micro glass particles are the reference particle system to demonstrate the correlation between single contacts and the particle packing properties. To investigate the influence of the van der Waals attraction force, the particles will be functionalized to obtain hydrophilic and hydrophobic surfaces. To remove the impurities and hydrophilize the particle surfaces a very strong oxidizing agent is used-the peroxymonosulfuric acid. In order to generate a hydrophobic glass surface, the process of silanization is applied. The comprehensive force displacement model of elastic-plastic and adhesive contacts are discussed. Therefore the model 'stiff particles with soft contacts' is used to quantify and compare the elastic-plastic contact properties. In this work, the particle contacts are experimentally investigated by means of atomic force microscopy (AFM), nanoindentation and shear tests. While the AFM and nanoindenter measurements are aimed to analyse single particle contacts, shear tests are used for particle packing studies. The fundamental challenge and question is addressed and answered: How do the micro mechanical material properties change when the glass surfaces are functionalized? Do we obtain the same behavior for the used micro glass particles when we compare the different methods?.