A method to prepare open cellular polymeric foams with uniform porous, low density and mechanical strength is developed using environmentally friendly processes. A polyolefin �blend� with bimodal molecular weight distribution is prepared by adding a small amount of polyolefin with higher MW to the one of lower MW. The �blend� is then saturated with carbon dioxide at prescribed pressure and temperature. By subsequent releasing of carbon dioxide to the atmosphere, an open-cellular porous materials is prepared. The open-cellular morphology occurs when the foaming temperature is above the melting point of the polyolefin when bubbles collapse (Figure 1 left); while for the bimodal �blend�, the almost perfect open-cellular morphology is obtained throughout the sample (Figure 1 right). A set of rheological measurements indicates the higher storage modulus at low frequency region for the bimodal �blend� due to the increased chain entanglement , which prevents the collapse of cells. Figure 1. Cell morphologies obtained from a polyolefin (left); and a bimodal blend (right)  Figure 2. Complex viscosity and storage modulus vs. angular frequency for a polyolefin and a bimodal �blend�

Carbon dioxide-assisted preparation of open-cellular polymer foams

248th National Meeting (2014)

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