Influence of hybrid nano-filler on the crystallization behaviour and interfacial interaction in polyamide 6 based hybrid nano-compositesElectronic supplementary information (ESI) available. See DOI: 10.1039/c5cp00018a

• Main Authors: Sreekanth, M. S, Panwar, Ajay S, Pötschke, Petra, Bhattacharyya, Arup R
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c5cp00018a

Expanded graphite (EG) and multiwalled carbon nanotubes (MWNTs) based hybrid nano-composites were prepared with polyamide 6 (PA6) matrix via melt-mixing technique using a conical twin-screw micro-compounder. A novel organic modifier (lithium salt of 6-aminohexanoic acid; Li-AHA) was employed to modify MWNTs, which was utilized to intercalate Li-AHA modified MWNTs into the partially exfoliated EG gallery. Morphological investigation showed the intercalation of Li-AHA modified MWNTs into a partially exfoliated EG gallery in an EG/MWNTs-m2h hybrid, whereas the unmodified EG/MWNTs-h hybrid mixture exhibited a separate identity in the mixture. Improved interaction via melt-interfacial reaction between the acid end group of PA6 and the amine functionality of Li-AHA in the EG/MWNTs-m2h hybrid filler was confirmed by Fourier transform infrared spectroscopic analysis. The extent of melt-interfacial reaction was increased as a function of Li-AHA concentration in the filler. Wide angle X-ray diffraction analysis showed the existence of the α-crystalline phase of PA6. The incorporation of MWNTs, EG and EG/MWNTs hybrid in the PA6 matrix has favoured an α-crystalline structure of the PA6 phase. Crystallization studies have indicated a significant increase in the bulk crystallization temperature of the PA6 phase in the presence of MWNTs, EG and the EG/MWNTs hybrid filler. Moreover, the formation of PA6 'trans-crystalline lamellae' on the MWNTs surface was facilitated in the case of composites with MWNTs and the EG/MWNTs hybrid filler. An attempt has been made to investigate the role of the EG/MWNTs hybrid filler in influencing the crystallization behaviour of the PA6 phase in the hybrid nano-composites. 'Agglomerated' and 'debundled' structure of EG/MWNTs hybrid providing hetero-nucleation to PA6 chain. The dispersion state of the hybrid filler in PA6 changes from 'agglomerated and stacked' state to 'debundled and exfoliated' state in the presence of Li-AHA modified hybrid filler.