Structure-property relationships in polyamide 12/halloysite nanotube nanocomposites

Polyamide 12 (PA12) nanocomposites based on halloysite nanotubes (HNTs) were obtained using a batch internal mixer or a twin-screw mini-compounder. In order to analyze the influence of HNTs dispersion on nanocomposite properties, morphological analysis (SEM and TEM) was combined with rheological and thermo-mechanical experiments. The linear viscoelastic properties and the dynamic storage modulus were expectedly found to increase with increasing HNT loading. Higher enhancements were observed for PA12/HNTs nanocomposites obtained by twin-screw mini-compounding. This finding was related to the better degree of dispersion and alignment of the silicate nanotubes throughout the matrix. Thermal stability was also improved by the halloysite nanotubes presumably by an entrapment mechanism of the volatile products inside the hollow tubular structure. DSC measurements further highlighted a nucleation effect of HNTs on the nanocomposites. In view of these results, halloysite nanotubes are promising candidates in the field of PA nanocomposites for structural applications.