Organosilane-functionalized halloysite for high performance halloysite/heterophasic ethylene–propylene copolymer nanocomposites

•Organomodification depends on the silane precursor and the reaction conditions.•Successful organomodification plays a key role in morphology and properties.•Hal modified with a hydrophobic silane can broaden polymer applications.

The surface modification of hydrophilic inorganic clays with organosilanes is a promising strategy to improve its dispersion as filler and interaction with hydrophobic polymers. Successful organomodification strongly depends on the characteristics of the silane precursor (functional group, chain size and concentration) and the reaction conditions (solvent polarity). This study correlates these factors with the morphological, thermal and mechanical properties of the final halloysite/heterophasic ethylene–propylene copolymer nanocomposites. When the halloysite (Hal) silane-modification was conducted in nonpolar solvents, the most efficient filler dispersion was achieved. Additionally, a good balance in the mechanical properties was obtained by using the more hydrophobic silane-modifier, improving the Young modulus in 38%, without loss of the impact properties at 23 °C. These optimized clay polymer nanocomposites exhibit properties suitable for many industrial applications.