ASTM E595 is a standard test method developed by ASTM International to evaluate the outgassing properties of materials in vacuum environments. This test is particularly important for applications where materials are exposed to high vacuum and can release volatile compounds that may condense on sensitive components, such as in space, aerospace, and electronics industries.
ASTM E595 is designed to measure the potential outgassing of materials under high vacuum. It specifically evaluates two main outgassing metrics:
Passing ASTM E595 indicates that a material has low outgassing properties, which is crucial in environments where even minimal contamination could compromise the function of sensitive equipment. This standard is frequently referenced in industries that require stringent material performance, such as aerospace, defense, and high-performance electronics.
Critical mechanical properties of silicone rubber that are important, depending on the application. These include:
The measure of a material’s ability to return to its original thickness after prolonged compressive stresses, which is particularly important in sealing applications.
The ability of silicone to resist deformation under load, which is important for parts that will undergo repeated bending or flexing.
The capacity of silicone to return energy upon deformation, which is relevant for dynamic applications like gaskets or vibration dampening.
Often referred to as Young’s modulus, this measures the stiffness of the silicone and its resistance to elastic deformation.
The ability of silicone to withstand cyclic loading, important for applications involving repetitive motion or vibration.
Resistance to surface wear or rubbing, crucial for components that are in contact with moving parts or experience friction.
The tendency of silicone to deform under prolonged stress, which is relevant in load-bearing applications over time.
The ability of silicone to absorb energy and resist shock, useful for components that may encounter sudden impacts.
This measures properties like viscoelastic behavior over a range of temperatures and frequencies, important for assessing performance under varying conditions.
These mechanical properties help determine how well silicone rubber performs under specific conditions and are crucial for selecting the appropriate formulation for an intended application.
Here’s a table summarizing the key mechanical properties of silicone rubber, along with their definitions, testing methods, and the relevant ASTM standards:
| Mechanical Property | Definition | Testing Method | ASTM Standard |
|---|---|---|---|
| Tensile Strength | The maximum stress that silicone rubber can withstand while being stretched before breaking. | A tensile test is conducted by stretching a specimen at a constant rate until it breaks, measuring the force applied and elongation. | ASTM D412 |
| Elongation | The extent to which silicone rubber can be stretched before breaking, expressed as a percentage of its original length. | Measured during the tensile test, calculating the change in length relative to the original length of the specimen. | ASTM D412 |
| Hardness (Shore A) | The resistance of silicone rubber to indentation, using the Shore A durometer scale. | A durometer is pressed into the silicone surface, and the resistance is measured to determine the hardness value. | ASTM D2240 |
| Tear Strength | The resistance of silicone rubber to the propagation of a cut or nick when under tension. | A specimen is prepared with a small notch and then stretched, with the force required to propagate the tear being measured. | ASTM D624 |
| Compression Set | The measure of a material’s ability to return to its original thickness after prolonged compressive stress. | A specimen is compressed to a specific percentage of its thickness for a set time and temperature, and the remaining deformation after release is measured. | ASTM D395 |
| Modulus of Elasticity | The stiffness of silicone rubber and its resistance to elastic deformation. | The modulus is calculated during a tensile test, by measuring the stress/strain ratio in the elastic deformation range. | ASTM D412 |
| Fatigue Resistance | The ability of silicone rubber to withstand cyclic loading or repeated stress without failure. | Silicone samples are repeatedly deformed or cycled to evaluate fatigue behavior over many cycles. | ASTM D430 (specific to fatigue tests for elastomers) |
| Abrasion Resistance | The ability of silicone to withstand surface wear or rubbing. | Abrasion is evaluated by measuring weight loss or surface damage after rubbing against an abrasive surface. | ASTM D5963 |
| Compression Deflection | The force required to compress a sample to a specific deflection, indicating stiffness under compression. | Silicone is compressed, and the force required to achieve a defined deflection is measured. | ASTM D575 |
| Creep | The tendency of silicone rubber to deform under prolonged load or stress. | Specimens are subjected to a constant load over a defined period, and deformation is measured over time. | ASTM D2990 |
These mechanical properties and their corresponding ASTM standards help characterize the performance of silicone rubber under various conditions, ensuring that the material meets the application-specific requirements and performs consistently.
At Konark, manufacturing silicone parts and components is our passion. Silicone rapid prototyping and silicone engineering is what we do best. Our goal is to take our customers from the silicone prototyping phase to high volume production in a robust, efficient and economical process.
