Characterization of perlite powders from Izmir, Türkiye region

Perlite is an amorphous volcanic glass-type rock which is collected in open mines in various parts of the world. In this study, eight different perlite samples, supplied from the mines located in the Bergama, Izmir region, were used. The perlite samples were structurally, morphologically, and mineralogically characterized via a wide range of analytical techniques such as Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) Surface Area Analysis, Optical Microscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and a liquid pycnometer. Platelet shaped-like structures were observed in the SEM analysis of the expanded perlites in contrast to the images of spongy or cracked expanded perlites reported in literature. The O-H bending and Si-O-Si vibrations (both asymmetric and symmetric stretching) of perlite structures were confirmed by FTIR. Highly amorphous phases with a rather low percentage of crystalline phases were observed by XRD. In the BET surface area analysis, expanded perlite materials exhibited higher surface area compared to unexpanded ones. A detailed characterization of perlite structures is essential as there is a significant potential to use these minerals in various biocomposite applications and it is useful to explain structure-property relationships in this class of materials.