Structural Evolution of Organo-Montmorillonite (Cloisite 15A) under High-Energy Ball Milling

Abstract

The structural evolution of organo-montmorillonite (Cloisite 15A) under high-energy ball milling was systematically investigated. Results show that frictional forces during milling promote layer peeling and increase structural disorder, enabling partial exfoliation of the clay. Exfoliation improved noticeably at higher milling speeds and lower ball-to-powder ratios. Using smaller milling balls further increased peeling efficiency by creating more intense frictional interactions, allowing similar exfoliation levels to be reached in shorter milling times. In contrast, larger ball-to-powder ratios increased collision effects, leading to structural deterioration and fragmentation of clay layers. Higher milling speeds also induced particle agglomeration, limiting exfoliation efficiency. Infrared spectroscopy and elemental analysis confirmed that the alkylammonium ions remained intact, indicating structural modification without loss of organic functionality. These findings highlight the distinct roles of friction and impact during mechanochemical processing and provide insights into optimizing ball milling conditions for effective exfoliation of organo-montmorillonite.