Polymer–Clay Nanocomposite Foams Prepared Using Carbon Dioxide

Abstract

drop of the suspension on a TEM grid, and letting the solvent evaporate slowly in a fume hood. XRD patterns were recorded on powder samples using a Philips PW1710 diffractometer (Cu Ka radiation, k = 1.54056 ) at a scanning rate of 0.02 s ±1 for 2h in the range of 10 to 70. UV-vis spectra were measured using a diode array spectrophotometer (Hewlett Packard 8452 A, Palo Alto, CA) with a resolution of 2 nm. Photoluminescence spectra were recorded using a luminescence spectrophotometer (Perkin Elmer LS-50B, Norwalk, CT) with pulsed high pressure xenon source. Polymer±Clay Nanocomposite Foams Prepared Using Carbon Dioxide** By Changchun Zeng, Xiangmin Han, L. James Lee,* Kurt W. Koelling, and David L. TomaskoPolymeric foams (or porous polymeric materials) are used in many applications because of their excellent strength-toweight ratio, good thermal and sound insulation properties, flexibility of generating desired morphologies to meet specific applications, materials savings, etc.[1] Foams with nanometersized voids are under investigation for potential applications as the next generation materials of low dielectric constants.[2]However, compared to bulk polymers, foams have reduced mechanical strength and lower dimensional and thermal stability. Recently developed microcellular foams provide improved mechanical properties over conventional foams,

Nanoscaled Reinforcement of Polystyrene Foams using Carbon Nanofibers

“…The foam morphology and properties greatly depend on the inclusion of nanoparticles. It has been reported that nanoparticles exhibit improved nucleation efficiency in the polymeric foaming processes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. With a low particle loading, microcellular foams with improved uniformity in foam morphology can be produced.…”

“…On the contrary, traditional thermoplastic foams, especially those generally considered as the insulation materials, are less attractive for these applications due to their inferior mechanical strength, poor surface quality, and low thermal and dimensional stability. In light of this, using nanoparticles to reinforce polymer foams has gained particular attention lately [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The foam morphology and properties greatly depend on the inclusion of nanoparticles.…”

Low density polyethylene/silica nanocomposite foams. Relationship between chemical composition, particle dispersion, cellular structure and physical properties

“…Several authors have concluded that when nanofillers are dispersed properly an effective nucleating effect, accompanied by an improvement in physical properties, is obtained. For instance, Zhen et al [13] demonstrated the high impact of the filler delamination level on the polymer foamability. They observed a higher cell nucleation efficiency with the exfoliated nanoclays than with the intercalated ones in both polystyrene (PS) and poly (methyl-methacrylate) (PMMA).…”

Carbon dioxide‐induced crystallization in poly(L‐lactic acid) and its effect on foam morphologies

“…[1][2][3][4][5] The morphologies generated via CO 2 processing are dependent on treatment pressures and temperatures, the physical properties of the polymer and the modifications thus induced as a result of contact with CO 2 . The solubility of CO 2 in a polymer leads to relaxation, chain mobility and hence reduction in the polymer's glass transition temperature (T g ).…”