Biaxial flow-induced alignment of silicate layers in polypropylene/clay nanocomposite foam

Via batch process in an autoclave, we conducted foam processing on polypropylene (PP)/clay nanocomposite (PPCN) by using supercritical CO2 as foaming agent under 10 MPa at 134.7 degreesC. Through transmission electron microscopy observation, the biaxial flow-induced alignment of clay particles along the cell boundary was identified. Such aligning behavior of clay particles helps cells to withstand the stretching force from breaking the so thin cell wall and to improve the modulus of the foam.