How to Measure Hardness of TPE Material

Basic Knowledge of TPE Hardness Measurement for Thermoplastic Elastomer
Introduction to articles:
1. Understand the hardness of TPE thermoplastic elastomer
2. Hardness Measurement of 2.TPE Thermoplastic Elastomer
3.TPE thermoplastic elastomer hardness measurement method
4. Relationship between 4.TPE Thermoplastic Elastomer Hardness Measurement Method and Other Properties
5. The relationship between different hardness scales
Text:
1. Understand the hardness of TPE thermoplastic elastomer
When selecting a thermoplastic elastomer (TPE), the hardness of the material is often one of the first indexes to be considered. Thermoplastic elastomer (TPE) can produce standard products with hardness ranging from Shore A 3 (softest) ⊙ to Shore A 95 (hardest). Hardness is defined as the dent resistance of a material when a static load is applied.
Hardness is also related to other important physical properties, such as tensile modulus and flexural modulus. Due to various measurement scales and hardness and the relationship with other material properties, confusion may occur when discussing hardness.
2. Hardness Measurement of 2.TPE Thermoplastic Elastomer
The most commonly used instrument for measuring hardness is called Shore durometer. The penetration depth measured by this instrument is zero to 0.100 inches. If the reading on the scale is zero, it means that the pressure head has penetrated the limit depth. Similarly, a reading of 100 indicates that the pressure head has not penetrated. The most common scale used is the Shaw A scale. Shore A durometer has a blunt pressure head and a spring with medium elasticity. When the reading exceeds 90, Shaw A instrument becomes inaccurate. When the hardness exceeds Shore A 90, it is more appropriate to use Shore D durometer.
This instrument uses a sharp pressure head and a spring with strong elasticity. The softer TPE uses the Shore 00 scale to measure materials with hardness less than Shore A 5. Most soft gels and soft foam rubbers are measured using the Shaw 00 scale.
3.TPE thermoplastic elastomer hardness measurement method
Most materials can withstand the initial pressure, but will yield over time due to creep and relaxation. The durometer reading can be read immediately or after a certain delay time, usually after 5 to 10 seconds. Immediate readings usually show higher (or harder) readings than delayed readings. Delayed readings are more representative not only for the hardness of the material but also for its resilience. Weaker and less elastic materials are more prone to creep than stronger and more elastic materials. Generally reported hardness is measured in degrees after 10 seconds.
4. Relationship between 4.TPE Thermoplastic Elastomer Hardness Measurement Method and Other Properties
Hardness is often confused with other characteristics, such as flexural modulus. Both reflect the tactility of the product. Flexion modulus represents the resistance of the material to flexure, and hardness represents the resistance of the material to indentation. Creep resistance is also directly related to tensile strength. The softer TPE has higher creep degree and lower tensile strength than the harder material. Friction coefficient (COF) is inversely proportional to hardness. As hardness increases, COF generally decreases. Generally, materials with higher hardness have better wear resistance.
5. The relationship between different hardness scales

Remark: The softest thermoplastic elastomer TPE material is mentioned in this article: The author's opinion is that Shore 3A may not be the softest TPE. Some TPEs have a hardness of 0A or even softer than 0A due to the particularly high proportion of oil added to the system. This is similar to OA's ultra-soft TPE. Measured by Shore C, the elastomer industry also uses the number of 0 to represent such ultra-soft TPE materials with a hardness softer than OA. Such ultra-soft TPE is used in products or industries such as adult products, medical mannequins, cushion pads and human body display props.