Hardness of TPE Thermoplastic Elastomer

Hardness of TPE Thermoplastic Elastomer

 

1: TPE hardness measurement

2: TPE measurement standard

3: relationship between hardness of thermoplastic elastomers and other properties

4: relationship between different hardness scales

 

Hardness definition

When choosing a thermoplastic elastomer (TPE), the hardness of the material is one of the first factors to be considered. Thermoplastic elastomers (TPE) produce standard products with hardness ranging from Shaw's A 3 (softest) to Shaw A 95 (hardest). Hardness is defined as the sagging resistance of the material under static loading. Hardness is also related to other important physical properties, such as tensile modulus and flexural modulus. Due to different measurement scales and hardness and their relationship with the properties of other materials, there may be confusion in discussing hardness.

Hardness Measurement of TPE Thermoplastic Elastomer

The most commonly used instruments for measuring hardness are referred to as Shao’s durometer. The penetration depth measured by the instrument is 0 to 0.100 inches . If the reading on the scale is zero , it means that the ram penetrates the limit depth . Similarly , a reading of 100 indicates that the ram does not penetrate . the most common scale is the shore a scale . The Shore A durometer has a blunt pressure head and a resilient middle spring . When the reading exceeds 90 , the Shao ' s A device becomes more accurate . When the hardness exceeds Shore A 90 , it is suitable to use a Shore D durometer . the use of such an instrument A sharp pressure head and spring with strong elasticity. The softer TPE uses Shao's 00 scale to measure the hardness of materials less than Shaw A 5. Most soft gels and flexible foams are measured using Shao's 00 scale.

Test method for hardness of TPE thermoplastic elastomers

Most materials can withstand initial pressure, but over time they succumb to creep and relaxation. Hardness meter readings can be read instantly or after a specific delay, usually after 5 to 10 seconds. Instant readings usually show higher (or harder) readings than delayed readings. The delay reading is more representative not only for the hardness of the material but also for its resilience. Weaker and less elastic materials are more likely to creep than elastic materials. Generally reported hardness is 10 seconds after the use of degrees.

 

Relationship between TPE hardness and other properties

Hardness is often confused with other properties, such as flexure modulus. Both reflect the touch of the product. The flexural modulus represents the resistance of the material to the flexure, and the hardness represents the resistance of the material to the compression. Creep resistance is also directly related to tensile strength. The softer TPE has a higher degree of creep and less tensile strength. The coefficient of friction (COF) is inversely proportional to hardness. When hardness increases, COF usually decreases. Generally, materials with higher hardness have better wear resistance.