Multi-walled carbon nanotubes (MWCNTs) incorporated polypropylene (PP) composites were prepared via a conical twin-screw micro-compounder, wherein MWCNTs were varied from 1-5 wt%. Morphological observation suggests 'agglomerate' dominated morphology in the respective composite, wherein 'remaining agglomerates' size is increased as a function of MWCNTs concentration. Oscillatory melt-rheological analysis indicates a rheological percolation threshold between 2-3 wt% of MWCNTs in the PP matrix, which manifested in the disappearance of the terminal behaviour in the lower frequency region of storage modulus versus frequency plot. In this context, it is to be noted that the influence of MWCNTs is more pronounced in the lower frequency region suggesting the dominant influence of various 'network-like' structures in the 'long-range' interaction between PP and MWCNTs. On the contrary, the respective composites show a lesser extent of 'short-range' interaction between PP and MWCNTs, in which all the composites merge to the value of pure PP in the higher frequency region. Further, MWCNTs were modified by a novel organic modifier (Li-salt of 6, amino hexanoic acid; Li-AHA) in combination with a polymeric compatibilizer (PP-g-maleic anhydride, PP-g-MA), which led to a higher fraction of 'individualized' MWCNT along with smaller MWCNTs 'agglomerates' in the PP matrix. In the context, a systematic investigation has been carried out to understand the role of Li-AHA modified MWCNTs plus PP-g-MA on the morphology and melt-rheological behaviour of PP/MWCNTs composites. It is important to mention that Li-AHA modified MWCNTs along with PP-g-MA led to a significant change in the high frequency behaviour along with low frequency behaviour in storage modulus versus frequency plot suggesting the dominant influence of 'individualized' MWCNTs on the 'short-range' and 'long-range' interaction in PP/MWCNTs composites.

Melt-rheology and morphology of multi-walled carbon nanotube-based polypropylene composites: Assessing the state of nanotube dispersion

2019 Spring National Meeting

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