High hardness silicone rubber filled with fumed silica or alumina

?High hardness silicone rubber was prepared by addition of fumed silica or alumina on the basis of Wacker R401/70S.Research indicated that the addition of fumed silica or alumina could improve the hardness of silicone rubber from 70(Shore A)to 90(Shore A).Much more alumina were added to achieve the same hardness of silicone rubber as compared with the silica.The silicone rubber stock prepared by the addition of alumina exhibited preferable performance of heat stability.Mechanical properties and heat stability of silicone rubber stock were improved evidently by the addition of silane coupling agents.The performances could be further improved by addition of the additives pretreated with silane coupling agents.The addition of cerium oxide could improve evidently the heat stability of the silicone rubber stock with exceptional hardness.