Investigations the effects of different fillers and flame retardant materials on fire resistances of LDPE/EVA based cable insulation materials

Aluminum hydroxide (ATH) is widely used as a filler/flame retardant in low-density polyethylene/ethylene vinyl acetate (LDPE/EVA) polymers, which are considerably preferred for cable sheath production in the cable industry. In this thesis, the usability of huntite hydromagnesite (HHM) was investigated as a potential alternative to ATH. Additionally, the synergistic effects of zinc borate (ZnB) and calcite were explored. Although the combustion behavior of the composite materials is of great importance in terms of their final performance, evaluating this behavior together with mechanical and physical properties has been deemed essential for accurately determining the overall performance of the composites. The composite materials produced in the studies were subjected to tensile strength, elongation at break, density, tear resistance, melt flow index (MFI), gravimetric water absorption and thermal aging conditioning for mechanical and physical evaluations. For thermal analysis, thermogravimetric analysis (TGA) was performed, while for the evaluation of combustion performance, limiting oxygen index (LOI) and UL 94 vertical burning tests were conducted. The results indicated that a matrix polymer blend of 75% EVA / 25% LDPE suitable for achieving the desired properties in the composites. Furthermore, the experimental findings demonstrated the feasibility of using HHM as a complete replacement for ATH. However, it was determined that adding 50% ATH / 50% HHM mixture to the matrix is more advantageous for the composite material to be used in cable sheath production. Although 2.5% and 5.0% substitution of ZnB (based on filler content) resulted in acceptable reductions in the mechanical properties, it was determined that fire resistance was enhanced to a certain level through a synergistic effect. In contrast, 5 % and 10 % substitution of calcite (based on filler content) led to slight decreases in the mechanical properties, but no effect on fire resistance was observed.