Lightweight and High Impact Polypropylene Foam Fabricated via Ultra-Low Gas Pressure Injection Molding

Abstract

Foamed materials play an important role in a lightweight design. Foam injection molding (FIM) is an advanced and convenient way to fabricate lightweight structural materials. Recently, a new foam injection molding machine is developed, which only needs ultra-low gas pressure to fabricate microcellular foam. As a universal plastic, polypropylene (PP) is widely used due to its good mechanical properties. But after foaming, the toughness of the PP tends to decrease. Herein, a lightweight and high-impact polypropylene foam is fabricated via the new FIM technology with an ultra-low nitrogen pressure of 6.5 MPa. PP/polyolefin elastomer (POE) foam with a tiny cell size of 4.13 µm and high cell density of 2.7 × 109 cm−3 is successfully obtained. Owing to the superior cellular structure, compared with the pure PP foam, after adding the POE component, the maximum impact performance is increased by 465%. In this work, an easy-to-industrialized method for preparing lightweight and high-impact injection-molded PP foams are presented.