Effect of Nanoparticle Dispersion

The effect of nanoparticle dispersion on the foam cell morphology is readily understood by the nucleation theories described above (Equation 1.1). As nanoparticles were better dispersed, higher effective particle concentration would have been achieved at the same nominal concentration. However, dispersion is critically important in obtaining good foam morphology. If the nanoparticle dispersion is not sufficient, nonuniform cellular structure may result (Manninen et al., 2005). 

Zeng et al. (2003) prepared PMMA nanoelay nanocomposites with different dispersions intercalated (PMMA/20A) versus exfoliated (PMMA/MHABS). 

FIGURE 1.11 (Continued) SEM micrographs (c) PMMA/5% MHABS nanocomposite foams at 120°C and COj pressure of 13.8 MPa. (d) Summary of cell size and cell density. (Reprinted with permission from Zeng C. et al., Advanced Materials 2003, 15, 1743-1747. Copyright 2003, John Wiley Sons.) 

Yeh et al. (2009) also found that the nature of the dispersion of organoclay plays a vital role in controlling the size of the cell during foaming and in exfoliated nanocomposites in particular, the individual particles enable a much larger interfacial area between clay particles and the polymer matrix to be used for cell nucleation. 

FIGURE 1.12 Bimodal cell size distribution observed in PMMA-lwt% CNT nanocomposite foams prepared at 13.8 MPa and different temperatures (a) 100°C (b) 120°C. 

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Chandran, S., Basu, J. Effect of nanoparticle dispersion on glass transition in thin films of polymer nanocomposites. Fur. Phys. J. E 34(9), 99 (2011)... 

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