Using multiple melt blending to improve the dispersion of montmorillonite in polyamide 6 nanocomposites

Polyamide 6 (PA6) was multiple melt-blended with organically modified montmorillonite (MMT) Cloisite 20A and Cloisite 30B and unmodified MMT Na+ in order to make three types of PA6/MMT nanocomposites. According to the morphology observation, the dispersion of silicate layers in the 20A nanocomposites was improved until it scattered, whereas the dispersion of silicate layers in the 30B nanocomposites is satisfactory. Moreover, the dispersion of silicate layers in Na+ nanocomposites slightly improved with the increase in melt-blending cycles. After PA6 was melt-blended with MMT, its molecular weight (MW) decreased with the processing cycles, which resulted in easy degradation. The mechanical property tests show that multiple melt blending has a positive influence on the mechanical properties of three PA6/MMT nanocomposites. However, their elongation at break and impact strength both decrease as a result of the aggravating degradation of PA6. Increasing the melt-blending cycles causes the crystallization temperature to increase and the melting temperature to decrease.