Study on properties of organic fiber/EPDM heat-insulating material

The effects of polyacrylonitrile (PAN) fiber and aramid fiber content on ablative rate and charring-layer porosity of EPDM insulation were studied respectively. The thermogravimetric (TG) curves of PAN fiber and aramid fiber in nitrogen and the SEM of charring-layer were analyzed. The results show that not only carbon residue ratio of PAN fiber is higher than that of aramid fiber, but also PAN fiber can be gradually pyrolyzed and carbonized within the wide temperature range; pyrolysis gas during the ablative process can be released quickly from charring-layer; the porosity of charring-layer is smaller, and the charring-layer is so tight and hard that it can effectively resist ablation and erosion of high temperature combustion gas flow; the ablative rate of insulating material is smaller. On the contrary, though aramid fiber has higher thermal stability, its thermal decomposition temperature range is very narrow; pyrolysis gas can hardly be released from the charring-layer quickly; the porosity of charring-layer is higher; the charring-layer is loose and presents lamellar, which cannot effectively resist ablation and erosion of high temperature gas, and the ablative rate is higher.