Physical properties of silicone rubber.

2 Mechanical engineer, USAMBRL. 3 Major, Army Medical Specialist Corps, USAMBRL. ROOM-TEMPERATURE-VULCANIZING (RTV) silicone rubber is a versatile material and easy to handle. The ingredients from which it is formed are thick liquids that vulcanize at room temperature within a short period of time after the catalyst is added. Depending upon the relative amounts of solid and foam ingredients, the consistency of the resultant rubber may range from a hard solid to a soft foam. Increasingly numerous applications of silicone rubber are being made in prosthetics and orthotics; for example, in fabricating distal pads for above-knee and below-knee sockets, shoe fillers for certain types of foot amputations, finger pads for prosthetic hands, and pads for braces. The material has been used successfully in medical implants. It is also useful as an exercising medium for strengthening the hand grasp, because a wide range of compressive forces can be obtained by varying the consistency of the foam rubber. An evaluation of the physical properties of silicone rubber made with varying proportions of ingredients was conducted at the U.S. Army Medical Biomechanical Research Laboratory. The results should enable users of this material to prepare foam specimens with predetermined characteristics to meet particular requirements. During this evaluation, samples were prepared and tested for density, compressive forces, and tear resistance. The material considered was a composition of RTV 385 solid elastomer, RTV 386 foam elastomer, and catalyst 386.