Properties of Nanocomposite Foams

The properties of the polymer nanocomposites are dictated by the types of nanoparticle used and the foam morphology. The foam morphology, in turn, is largely determined by the nanocomposite synthesis (nanoparticle dispersion) and foaming conditions. Due to the complicated nature of the interactions between nanoparticles, bubbles, and matrix, the influence of nanoparticles on the properties of nanocomposite foams is still not fully understood (Bauhofer and Kovacs, 2009 Chen, Ozisik, and Schadler, 2010 Moniruzzaman and Winey, 2006). 

In addition, the authors developed a constitutive model for predicting the compressive mechanical properties of polymer nanocomposite foams with densities lower than 0.5. Finally, they clearly showed that the morphology controlled the final properties of nanocomposite foams since foams composed of small cells led to better mechanical properties. 

Ghasemi I, Farsheh AT, Masoomi Z. Effects of multi-walled carbon nanotube functionalization on the morphological and mechanical properties of nanocomposite foams based on polyfvinyl chloride)/(wood flour)/(multi-walled carbon nanotubes). J Vinyl Addit Technol 2012 18 161-7. 

A literature survey on polymer nanocomposite foam lays emphasis on the fact that nanofillers play a vital role in the enhancement of the mechanical properties of foams because they enhance the matrix and modify the foam structure. While huge progress has been made with respect to the understanding of the mechanical properties of polymer foams, more work is needed to fully reveal the relationships between various mechanical properties and foam structure, so that the properties of foams can be optimized. 

Overall, in this section, the role of nanofillers in the improvement of foam properties was discussed and recent studies regarding new nanocomposite foams with superior properties were reviewed. In general, nanofillers can improve the properties of polymer foams by improving the properties of the matrix, thereby changing the structure of the foams through heterogeneous nucleation and by providing additional functionality to the neat polymer foams. 

Recent publications describe the effects of silica on the conductivity and mechanical properties of a polyethylene oxide/ammonium bifluoride complex containing propylene carbonate [36], as a foam stabilizer in polyester polyurethane foams, and on the properties of polylactic acid nanocomposites prepared by the sol-gel technique [37] (see also Chapter 24), on the mechanical properties and permeability of i-PP composites [38], on the surface hardness of polymers for biomedical devices [39], on enhanced properties of polymer interlayers that are used in multiple layer glazing panels [40]. 

Frydrych M, Wan C, Stengler R, O Kelly KU, Chen B (2011) Stmcture and mechanical properties of gelatin/sepiolite nanocomposite foams. J Mater Chem 21 9103-9111... 

Quadrini et al. developed a solid-state process to yield epoxy foams with different contents of nanoclay (up to 10%wt) [86]. They demonstrated excellent shape memory properties for the nanocomposite foams with low filler loadings and were able to control porosity by varying the solid precursors during the foaming process. 

Frydrych, M., C. Wan, R. Stengler, K.U. O Kelly, and B. Chen. 2011. Stiucture and mechanical properties of gelatin/sepiolite nanocomposite foams. Journal of Materials Chemistry 21(25) 9103-9111. 

El-Kady, A.M., Rizk, R.A., Abd El-Hady, B.M., Shafaa, M.W., Ahmed, M.M., 2012. Characterization, and antibacterial properties of novel silver releasing nanocomposite scaffolds fabricated by the gas foaming/salt-leaching technique. Journal of Genetic Engineering and Biotechnology 10, 229-238. 

TABLE 17.3 Morphological Properties of Unfoamed and Foamed PLA/Nanocomposites [39, 41]... 

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