Physical Characteristics
Durometer Hardness
Durometer is one of several ways to indicate the hardness of a material, defined as the material's resistance to permanent indentation.There are several scales of durometer, used for materials with different properties. The two most common scales, using slightly different measurement systems, are the ASTM D2240 type A and type D scales. Each scale results in a value between 0 and 100, with higher values indicating a harder material.
Color
The color of tubing often depends on the material being used and is often simply cosmetic. Color can be added to a tubing formulation for a custom look or to coordinate with an existing product.
Temperature
Since tubing is produced from a variety of polymers, elastomers and rubbers, temperature should be considered in the selection of a tubing formulation for an end-use application. As a rule, tubing will stiffen as ambient temperature is reduced from standard room temperature (73°F/23°C). At higher temperatures, the tubing will become more flexible and physical properties such as tensile strength will become lower.
Tensile Strength
Tensile strength measures the force required to pull a polymer material to the point where it breaks or permanently deforms. Once the tensile strength of the tubing has been surpassed, the tubing can become brittle causing reduced flow rates and contamination.
Ultimate Elongation
Ultimate elongation is the elongation of the tubing at the moment of rupture. The more flexible the material is, the greater the elongation. Elongation is inversely related to the materials hardness and tensile strength. The greater the hardness and tensile strength, the less the polymer will elongate.
Tear Resistance
Tear resistance measures the ultimate force required to tear a polymer material. This test is often used for material comparison where tear failures are possible. Tear resistance is an important property to consider, ensuring the product is performing the necessary functions.
Specific Gravity
Specific gravity is a way to express the relative density of a polymer material. It is measured as the ratio of the density of the material to the density of water. It is expressed as a number which indicates how much heavier the material is compared to an equal volume of water.
Water Absorption
Water absorption is the measure of the amount of water absorbed by a material when subjected to certain conditions. There are several factors which can affect the water absorption including material used, temperature and the fluid being transferred.
