Field emission scanning electron microscopy
Fig. 7.7A—F shows FESEM images of the fractured cross-sectional surfaces of neat PLA, P/MT5 nanocomposite, P/MT5/CW-CS1, P/MT5/CW-CS3, P/MT5/CW-AH1, and P/MT5/CW-AH3 hybrid nanocomposites, respectively (Arjmandi et al., 2015b, 2016). Fig. 7.7A shows that neat PLA has a typically smooth fracture surface (Jiang et al., 2007). Fig. 7.7B presents the fractured cross-sectional surfaces of P/MT5 nanocomposites. It can be seen that MMT disperses uniformly throughout the PLA due to its finer particle size, as indicated by arrows (Chang et al., 2003a). As can be observed from Fig. 7.7C—F, there is no clear evidence about the presence of the individual CNW-CS and CNW-AH in the hybrid nanocomposites because of nanosize shapes of CNW-CS and CNW-AH. From Fig. 7.7C, E, it can probably suggest that the CNW-CS and CNW-AH disperses uniformly throughout the PLA; MMT fillers are indicated by the white arrow and the CNW-CS and CNW-AH particles by the red arrows. Accordingly, the interaction between the matrix and the fillers has enhanced considerably, as reflected by an increased tensile strength. Meanwhile, at higher filler content filler— filler interactions are more favorable than
Figure 7.7 FESEM micrographs of fractured cross-sections of (A) neat PLA; (B) P/MT5 nanocomposite; (C) P/MT5/CW-CS1; (D) P/MT5/CW-CS3; (E) P/MT5/CW-AH1; and (F) P/MT5/CW-AH3 hybrid nanocomposites.
Source: Aijmandi, R., Hassan, A., Eichhorn, S.J., Haafiz, M.M., Zakaria, Z., Tanjung, F.A., 2015b. Enhanced ductility and tensile properties of hybrid montmorillonite/cellulose nanowhiskers reinforced polylactic acid nanocomposites. J. Mater. Sci. 50 (8), 3118—3130 and Arjmandi, R., Hassan, A., Haafiz, M.K.M., Zakaria, Z., Islam, M.S., 2016. Effect of hydrolysed cellulose nanowhiskers on properties of montmorillonite/polylactic acid nanocomposites. Int. J. Biol. Macromol. 82, 998—1010.
filler—matrix interactions, leading to filler agglomeration (Fig. 7.7D, F). From Fig. 7.7D, F, agglomeration of the MMT filler (circled area) and the CNW particles (red arrows) in the P/MT5/CW-CS3 and P/MT5/CW-AH3 hybrid nanocomposite can be seen. This agglomeration plays a major role in decreasing the tensile strength of the hybrid nanocomposites.