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According to the United States Department of Commerce, the domestic medical device market — the largest in the world — has a market size of $110 billion. The forecast points to an increase to $133 billion by 2016. In 2012, 6,500 medical device companies garnered a 38 percent share of the global marketplace for medical products and devices. The medical device industry consists of a broad range of products and technologies, including appliances, materials, apparatuses, and other items. These products function as standalone products or in combination with other parts and products for diagnosis, monitoring, mitigation, treatment, compensation, and prevention of diseases and other conditions.
The density, or its reciprocal, the specific volume, is a commonly used property for polymeric materials. Density is primarily used as a material control tool, as well as to compare the buoyancy of different materials, but it can also be used to calculate the mass of rubber required to produce a given volume of material. The density of compounds with fillers or different materials can be computed at any temperature using the rule of mixture. Density measurements are performed following the standard tests ISO 1183 and ASTM D792. The density of Liquid Silicone Rubber (LSR) is typically in the range of 1.10 – 1.50 g/cm3 (density of natural rubber: 0.92, EPDM: 0.86 g/cm3), so it will sink in water (density of water: 1 g/cm3).
Liquid Silicone Rubber (LSR) is often utilized for seals, valves and diaphragms, due to its high elongation (between 400 and 700% at room temperature) and tensile strength over a wide temperature range. The tensile properties of thermoset rubbers and thermoplastic elastomers need to be measured/tested in order to verify that the quality control standards of Silicone Rubber Liquid are met, as well as to determine whether or not the material is fit for its purpose. The test should be performed according to ASTM D412, which describes two test methods: A and B.
The hydrophobic methyl side groups of Liquid Silicone Rubber (LSR) account for its low surface energy and water repellence. An average value for silicones is 24 dynes/cm or 0.024 N/m. The surface hydrophobicity of a solid surface is determined by its free surface energy. ASTMD2578 (or ISO 8296) is the most employed technique to study loss and recovery of hydrophobicity of silicones, which is calculated by measuring the contact angle. The method is very time efficient, and inexpensive instruments can be utilized. It is often defined on the basis of the static contact angle between the surface and a water droplet, in which a surface can be considered hydrophilic if the contact angle is 90˚.