The hydrophilic monomer, acrylic acid (AA), has been grafted onto hydrophobic silicone rubber (SR) film via the gamma-ray preirradiation graft technique. The AA percent graft in SR-g-AA film increases with increasing irradiation dose rate. The iron powder in monomer solution serves as one source of ferrous ion that is generated by the oxidation reaction with water. The swelling effect shows that the amount of chloroform taken up by an SR-g-AA membrane decreases with the increasing AA grafting, and the amount of water, alcohol, and glycerol taken up by an SR-g-AA film increases with increasing AA percent grafting. The contact angle, ultimate stress, and elongation at break of SR and SR-g-AA copolymers decrease with increasing AA percent grafting. The oxygen/nitrogen selectivity in these films can be enhanced by the graft modification. The thermal behaviors of SR-g-AA copolymers show the characteristics of SR and polyacrylic acid. Finally, the dielectric properties show that the SR-g-AA film has a superior dielectric property than the original SR and poly(AA) matrix.