The solubility parameter value (SP value, 8) is one of the most important factors in bonding technology. It was found that various kinds of rubber, such as VMQ (delta = 7.3 cal(1/2)/cm(3/2)) compounds, EPDM (delta = 7.9 cal(1/2)/cm(3/2)) compounds, and X-NBR (delta = 9.3 cal(1/2)/cm(3/2)), can bond to poly(oxy-2,6-dimethyl-1,4-phenylene) in their vulcanization process. This means that this bonding mechanism depends less on SP values. In this study, the bonding mechanism is hypothesized as an interfacial radical reaction, and the hypothesis is validated by molecular orbital (MO) calculations and experiments. All experimental results and MO calculation results are consistent with each other. (C) 2004 Wiley Periodicals, Inc.