Abstract: Disclosed is rubber composition which can preferably be used for the components requires high damping capacity such as rubber dampers for use in the structures, public works, vehicles, oversize powered machines, and heavy weight structures; and general purpose dumpers for use in sound products, a variety of meters, the components of the vehicles, and the like in the case of a little amount of use. The rubber composition is characterized by having a complex shear elastic modulus of 1-20 kg/cm.sup.2 and a Tan.delta. of 0.40-1.5 at 30.degree. C. under a frequency of 0.5 Hz.+-.50% comprising:a) 100 parts by weight of polyisobutylene;b) x parts by weight of filler for use in rubber;c) y parts by weight of carbon black having an iodine adsorption of 20-120 mg/g;wherein the value x and y satisfy the relation that:x.ltoreq.450, y.ltoreq.150, andx+y.gtoreq.100.

Abstract: Disclosed is a rubber composition having high damping capacity as well as other excellent performances, for example, dependence of elastic modulus on temperature, shear deformation, etc., which is suitable for the laminated vibrationproofing structure. The rubber composition contains carbon black for use in rubber having an iodine adsorption of 70 to 115 mg/g and DBP adsorption (method A) of 115 to 70 ml/g in an amount of 30 to 70% by weight based on 100 parts by weight of a base rubber. The rubber composition is characterized by further containing:an aromatic petroleum resin having a softening point of 70.degree. to 140.degree. C. and a bromine value of 0 to 0.2; andcumarone-indene resin and/or rosin in the ratio which satisfies the relation: ##EQU1## wherein A is a total amount of cumarone-indene resin and rosin formulated, B is an amount of an aromatic petroleum resin formulated and B is not 0.