Nucleating effect of surface modified MWNTs on crystallization of MWNTs/PA6 composites

The surface characteristic of multi-walled carbon nanotubes (MWNTs) plays an important role in the crystallization of polyamide 6 (PA6). In this paper, 1,6-hexamethylenediamine(HMD) are grafted on MWNTs. The MWNTs before and after modification are used to fabricate PA6 composites through melt-blending. The nucleating effect of MWNTs with different surface characteristic is investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD). The heterogeneous nucleating ability of MWNTs determined by the Dobreva method are higher for pristine than amine-functionalized MWNTs/PA6 composites with 1.0 wt% MWNTs. Addition of MWNTs induce more heterogeneous nucleation and retards the crystal growth of PA6. The presence of MWNTs facilitates the formation of crystalline form, while amino-functionalization weakens this trend. MWNTs act as effective nucleation agents for PA6, resulting in the increased number and decreased size of spherulites. MWNTs facilitate the formation of crystalline form of PA6. Amino-functionalization decreases the crystallization and nucleating effect of MWNTs on PA6