Abstract-In this study, design experimental by two-level Factorial design to screen the factors to those factors that affect the ablation rate significantly. The following parameters were varied: amount of phenolic curing temperature and curing time. Factors that affect the ablation rate are as follows curing time, amount of phenolic resin, interaction between curing temperature and curing time, interaction between curing time and amount of phenolic resin, interaction between curing temperature and amount of phenolic resin and 3-way interaction of amount of phenolic resin, curing temperature and curing time. As the results of main effects analysis to determine 75 wt.% of phenolic resin, curing temperature 160 °C and curing time 35 min to give the ablation rate was 0.121 mm/s less than 0.14 mm/s according MIL-l-24768 standard.

Abstract. This study focused on improving the ablation properties and mechanical properties of natural rubber (NR)/ethylene propylene diene monomer (EPDM) blends by using two different commercial fillers: sepiolite and silica. The results showed that sepiolite and silica similarly improved both properties in the loading range of interest (0-12.5 phr). However, sepiolite was superior than silica as using less loading to acheive comparable mechanical and thermal properties. The optimum loading of sepiolite was 5 phr, while that of silica was 10 phr. For both filler systems, the minimum ablation rate found was approximately 0.17 mm/s, and the tensile strength and the hardness of corresponding NR/EPDM composite were improved after modification with sepiolite or silica.Thus, the composite reinforced with sepiolite or silica is suitable for many applications, such as internal insulations of rocket motor.

Abstract-To reinforce the mechanical properties of the rubber compounds, the silica was added. In this work, we measured the tensile strength and hardness of the compounds, in which the amounts of sulphur and silica were varied from 45 to 60 phr and 5 to15 phr, respectively. The experimental results showed that the addition of 10 phr silica 10 provides the maximum tensile strength and hardness. However for the amount of silica higher than 10 phr, the tensile strength tended to decrease. We also observe that the amount of sulphur 60 phr with 10 phr silica gives the maximum hardness (73 shore D).