Thermal behaviour and flame retardancy of modified polyurethane coatings
A study by Polish researchers provides information on the thermal behaviour and flame retardancy of polyurethane high-solid coatings modified with cyclophosphazene.
Hexakis(2,3-epoxypropyl)cyclotriphosphazene was employed for the preparation of high-solid hybrid organic-inorganic poly(urethane-cyclophosphazene) coatings based on epoxy-terminated urethane oligomer which were cured with ethylenediamine.
Thermal degradation occurrs in two stages
The flame retardancy, thermal degradation behaviour and some surface properties of the coatings were investigated. The results of thermogravimetric analysis suggested that thermal degradation of poly(urethane-cyclophosphazene) occurred in two main stages and the introduction of cyclophosphazene resulted in increase of thermal stability. The main gases released during thermal decomposition of the samples were carbon dioxide, ammonia, water and tetrahydrofuran.
Flame retardancy confirmed
The microscale combustion calorimetry revealed that the maximum specific heat release rate and the heat release capacity of the hybrid materials decreased significantly with incorporation of cyclotriphosphazene. The water contact angle and gloss decreased while hardness increased with the increase of hexakis(2,3-epoxypropyl)cyclotriphosphazene contribution in the coating.
The study is puplished in: Progress in Organic Coatings, Volume 108, July 2017, Pages 51–58
