IFR is a new flame retardant system, typically composed of acid sources, carbon sources, and gas sources. When heating, the polymer containing this flame retardant forms a uniform carbon foam layer on the surface, which provides heat insulation, oxygen isolation, smoke suppression, and prevents molten drips, thus delivering excellent flame retardancy.

✦Inferior compatibility with polymer substrate. Because of incompatibility of intumescent flame retardants and polymers, it leads to a reduction in electrical and insulating properties, especially significant drop in mechanical properties such as tensile strength and impact resistance.

✦Moisture absorption. For example, in the APP/PER/MA intumescent systems, it is easy to absorb moisture along with stickiness and lower thermal stability. Moreover, the components are prone to alcoholysis, causing inferior water resistance in flame-retardant polymers.

✦Based on low molecular weight, the common intumescent flame retardants tend to migrate to the polymer surface and deteriorate the physical and mechanical properties, particularly affecting the appearance.