7Effects on Thermal and Ablative Properties of Phenolic Resin (Novolac) Blended Acrylonitrile Butadiene Rubber

In this work we investigated the ablative response and thermal properties of phenolic resin (PR) blended acrylonitrile butadiene rubber (NBR) composites. PR was added to NBR in the proportion of 0, 5, 10, 20, 30, 40 and 50 phr by means of two-roll laboratory mill. PR remarkably improved ablation resistance and thermal properties of NBR/PR composite. The linear and mass ablation rates reduced to 21.3 % and 26.1 % respectively. The char content deposition increased from 0.19 to 26.8 %. Char layer produced by PR, obviously reduced the erosion rate of the NBR/PR composite relative to neat NBR (without PR). Detailed morphological studies of the composite and post-test (ablation) microstructure of char revealed that higher loading of PR in the rubber composite produced dense char layer firmly intact to the substrate. Furthermore, thermal stability of the composite improved by 22–23 oC, however, thermal conductivity of the composite slightly increased by 0.115 W/mK for 50 Phr of PR loading as compared to the neat.