Expandable graphite is recognised as an effective flame retardant because of its ability to absorb thermal energy by thermal liquid–gas conversion of the intercalant between the layers in its lamellar structure. Kevlar is widely used in protective clothing due to its excellent mechanical strength and thermal resistance; however, like many materials, it is vulnerable to degradation when exposed to high-energy laser systems, which causes carbonisation and material disintegration. This study demonstrates that coatings of expandable graphite can significantly enhance the thermal protection of Kevlar against 100 W laser radiation, up to 290 J/m2, with no detectable thermal damage on the side facing the wearer, using 25 g/m2 of expandable graphite. At the same loading (25 g/m2), the material containing expandable graphite provides adequate protection even at higher intensities, with degradation only starting at the highest intensity tested. Coating durability tests showed that the coating, especially when expandable graphite was included, protected the Kevlar substrate from abrasion for at least 10,000 cycles, making it suitable for applications such as laser-protective gloves.
Coetzee et al. (Thu,) studied this question.