is less than 50 and the hardness exceeds 75 the touch as rubber switches is inferior or if the hardness is less than 50 and the impact resilience is over 75 injection molding properties are lowered the composite having such mechanical properties is obtained for example by melting and kneading 40 parts by weight of isobutylene isoprene rubber 46 parts by weight of hydroxy terminated polyethylene adipate 2 parts by weight of 1 4 butanediol and 12 parts by weight of diphenyl methane diisocyante in a twin shaft extruder at a cylinder temperature of 210 u00b0 c it is also obtained by melting and kneading 10 parts by weight of isobutylene isoprene rubber 73 parts by weight of hydroxy terminated polyethylene adipate 3 parts by weight of 1 4 butanediol and 14 parts by weight of diphenyl methane diisocyanate in a twin shaft extruder at a cylinder temperature of 210 u00b0 c the polymer composite of the invention possesses the flexibility and durability equivalent to those of silicone rubber and is excellent in injection molding properties and inexpensive besides the polymer composite of the invention can be manufactured in a short manufacturing process because it can be obtained by a one shot polymerization technique furthermore the polymer composite of the invention has excellent.