Fabrication strategy for long‐chain branched polypropylene foams with high resilience and compressive strength

Abstract

A flexible and controllable is proposed for fabricating long-chain branched polypropylene (LCBPP) foams with high resilience and strength. LCBPP was blended with thermoplastic polyester elastomer (TPEE) using polyethylene octene elastomer grafted glycidyl methacrylate (POE-g-GMA) as a compatibilizer at different mass ratios, and the blends were then used to prepare foams at different temperatures by the supercritical CO 2 batch foaming method. The foams were then tested for their compressive permanent strain and compressive strength. The results showed that introducing TPEE and POE-g-GMA increased the resilience. In particular, the permanent strain of the LCBPP/ TPEE/POE-g-GMA foam at a ratio of 90/10/7 decreased from an initial 14.5% for the original LCBPP foam to 5% after five compression cycles. However, the compressive strength decreased from 65.59 to 39.82 kPa. Therefore, the foam density (ρ) and cell size (d) were adjusted to balance the resilience and strength. Increasing ρ/d from 0.32 to 3.10 increased the compressive strength significantly from 39.82 to 91.67 kPa while the permanent strain only increased 3.5%. Thus, the proposed strategy realized LCBPP foams with high resilience and compressive strength.