Determining the best flame retardant for rigid polyurethane foam—Tris(2‐chloroisopropyl) phosphate, expandable graphite, or silica aerogel

Although rigid polyurethane foams (RPUFs) have great thermal insulating properties such as its low density, low thermal conductivity, and high compressive strength, they have limited usage because pristine PU foams are highly flammable. Therefore, in order to have widespread applications, much attention has been invested in the discovery and study of a vast number of flame retardants. In this work, analysis on the physical, chemical, mechanical, and thermal properties of RPUF composites prepared with industrially‐used flame retardants, namely tris(2‐chloroisopropyl) phosphate (also known as TMCP or TCPP) and expandable graphite (EG), together with the highly promoted silica aerogel, was performed. Taking into account the overall performance, it was found that EG was the best among the three flame retardants investigated.