Sepiolite as replacement of short glass fibre in polyamide composites for injection moulding applications

Abstract Sepiolite polyamide 6 nanocomposites were prepared via melt compounding and in situ polymerization. The effects of the preparation approach, the amount of the clay and the surface clay modification were evaluated in order to check their influence on morphology, thermal, mechanical and flow behaviour of the final nanocomposites. Regardless of the preparation method, all nanocomposites showed good dispersion of the sepiolite in the matrix and significant improvements in Young's modulus, tensile strength and heat-distortion temperature were achieved. However, the nanocomposites obtained in one-step by in situ polymerization presented slightly better mechanical properties, than the obtained by melt compounding, due to the greater dispersion of the nanoclay within polyamide matrix. Especially interesting were the materials reinforced with modified sepiolite, where the grafting of an aminosilane onto the sepiolite surface produced important increases in the elongation at break and impact values as consequence of the improved stress transfer between the sepiolite and polymer matrix. Furthermore, nanocomposites with 10 wt% of sepiolite have been compared with higher loaded glass fibre polyamide. The nanocomposites presented similar or even better performances than commercial composites offering an important weight reduction for final applications.