Carbon nanotube network and interphase in buckypaper nanocomposites using atomic force microscopy

The CNT network and interphase in nanocomposites have not been studied quantitatively enough in the literature. The AFM peak force quantitative nanomechanics mapping technique was applied to polymer nanocomposites (PNC) reinforced with 0.5 wt% MWCNT and CNT buckypaper (BP). The DMA, BJH, SEM, and tension stress-strain curves were studied. BP is heterogeneous due to its local porous structure and nonuniform resin impregnation. The Interphase thickness for the CNT network is 26.8 ± 7 and 17.4 ± 5.1 nm in BP PNC and 0.5 wt% MWCNT PNC. The interphase thickness between infiltrated BP and polymer is ∼40 ± 4 nm. The CNT network sizes in BP PNC (108.5 ± 21.3 and 45.4 ± 10.3 nm) are influenced by the size of inter-bundle and intra-bundle pores. The interphase thickness normalized to the CNT network size is at least ∼7 times higher in BP PNC compared to 0.5 wt% MWCNT PNC, confirming pronounced interphase effects in the former. The Kolarik, Quali, and Takayanagi models for nanocomposite moduli were evaluated.