Hydrophobic modification of polypropylene/starch blend foams through tailoring cell diameter for oil-spill cleanup

Abstract

Frequent oil spillages and industrial discard of many organic solvents have created severe environmental and ecological problems. Therefore, it is imperative to find effective absorbent materials with high performance. Simultaneously, a green process of preparing such absorbent materials should be developed. Herein we present a facile approach to prepare open-cell polypropylene (PP)/starch blend foams with low density by twin-screw extrusion using water as a physical blowing agent and starch as an effective water carrier. The cell diameter of the prepared PP/starch blend foams was controlled by using different nucleating agents and changing the die geometry. Foams with mean cell diameter in the range of 0.4–4.5 mm and open-cell content larger than 90% were successfully obtained. Moreover, a remarkable improvement of hydrophobicity of the foams was obtained when decreasing the cell diameters. Consequently, the water contact angle and oil recovery efficiency were increased up to 142.2° and 98.4%, respectively, when the mean cell diameter was reduced to 0.4 mm. These characteristics make this foam a promising candidate absorbent material for use in oil-spill cleanup.