Foaming and Physical Properties, Flame Retardancy, and Combustibility of Polyethylene Octene Foams Modified by Natural Rubber and Expandable Graphite

Abstract

Flame‐retardant blends of polyethylene‐octene elastomer (POE) and natural rubber (NR) filled with expandable graphite (EG) were melt‐mixed with azodicarbonamide to prepare elastomeric foams. The effect of the NR incorporation on the properties of EG filled POE foam was investigated. Gel content and microstructure observations revealed that the addition of NR into the POE/EG blend induced change in molecular structure, which produced a finer cellular structure during foaming. The compressive strength and elastomeric recovery of the POE/NR/EG blend foams were found to increase with increasing NR content. Based on the limiting oxygen index and horizontal burning measurements, all the POE/NR/EG blend foams were found to have good flame‐retardant properties. On the other hand, these POE/NR/EG blend foams exhibited higher combustion rates with an increasing NR content under high heat radiation and temperature in a cone calorimeter test. This study demonstrates that the combined use of NR as a modifier and EG as a flame retardant in POE foams provides an effective and practical method of obtaining well‐balanced improvements in cellular structure, mechanical properties, and flame resistance.