Effect of aramid and carbon fibers with nano carbon particles on the mechanical properties of EPDM rubber thermal insulators for solid rocket motors application

Abstract The effect of varying compositions (5, 10, 15, 30 Phr) of aramid fiber in the pulp form Kevlar (KP), carbon mono fiber (CMF), and nano-carbon black (NCB) as filler for Trilene liquid polymers - Ethylene propylene diene monomer (EPDM) on mechanical properties were examined. All formulations contained 100 Phr EPDM, 60 Phr Ammonium polyphosphate (AP), and 5Phr Peroxide Crosslinking Agent (PCA). To improve the mechanical properties such as tensile strength, elongation, and hardness of EPDM Rubber thermal insulation used in the solid rocket motors, Twenty -Four samples with different formulations were tested at a tensile rate 50 mm/min and temperature 25 °C. The results indicated that composition containing KP has high storage modulus and tensile strength. EPDM rubber composite containing a ratio of 10 Ph kP+ 5 Phr CMF+ 5 Phr NCB showed better mechanical properties comparable with those of the KP/CMF, KP/NCB, or CMF/NCB filled EPDM. The tensile strength, hardness, and elongation have been slightly improved, fulfilling the thermal insulation requirement for solid rocket motors and the requirement of aging of thermal insulation for good pot life.