Development Of High Temperature Insulation Compound Based On EPDM/Polyimide/CNF Nanocomposite

Elastomers are extensively used in thermal insulation system. Among different elastomers, EPDM has interesting properties, such as excellent resistance to ageing and oxidative degradation due to its saturated back bone. It has been found that launch vehicles essentially need highly thermally stable casing over the propellant metal case. This casing should have ablative materials with low density and low thermal conductivity. During navigation, launching system of rocket is subjected to intense heat and immense pressure and hence insulation system is required for thermal protection at extremely high temperature. Furthermore, introduction of polyimide (PI) to the base elastomer is responsible for increasing its thermal stability. On the other hand, carbon nano fiber (CNF) reinforces the matrix to enhance the mechanical properties with an additional advantage of better char yield. To achieve better rubber-filler compatibilization, modification of EPDM was carried out by grafting with maleic anhydride (MAH). The maleic anhydride grafted EPDM (EPDM-g-MAH) was then compounded with PI and CNF. A workable formulation of maleated EPDM with ablative polyimide and CNF can be used under extreme environmental conditions and hence can act as an insulator on rocket motor case. Morphological studies by SEM and HRTEM exhibited uniform dispersion of nanofillers throughout the EPDM-g-MAH matrix. Thermal properties of the EPDM/polyimide nanocomposites were characterized by TGA, DSC and DMA. Besides these, thermal conductivity, thermal diffusivity and specific heat were also measured. Desirable physical and thermo-mechanical properties were achieved in frozen formulation of PI and CNF filled maleated EPDM matrix.