The Effect of Various Flame Retardants on Thermal Properties of Cable Insulation

Cables are used in many areas of industry. Their insulation system is mainly made of polymeric materials, so its flammable properties limit its use. For this reason, flame retardant fillers are added during production to improve heat resistance. Aluminium hydroxide (ATH - Al(OH)3) and magnesium hydroxide (MDH - Mg(OH)2) belong among the most frequently used flame retardants. Generally, flame retardancy occurs during the decomposition of these substances. The process is associated with the release of water and the absorption of heat (endothermic reaction). As the two flame retardants mentioned above have different decomposition temperatures, the properties of the resulting insulation are affected. Therefore, this paper compares the behavior of three cable insulations with different flame retardant incorporation. Simultaneous Thermal Analysis (STA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and Fourier Transform Infrared Spectroscopy (FT-IR) were used for the comparison of samples. The results indicate the different behavior of these insulations over a wide temperature range. The evaluation was based on analyzing the glass transition temperatures, decomposition temperatures, and mechanical moduli change during thermal heating.