Do you know what thermoplastic elastomer (TPE) products are like? They are flexible material with low modules. These products can also be stretched frequently to double their actual length at normal temperature. Thermoplastic elastomers are so flexible that they return to their actual length when the pressure is released from the material. The traditional material with the aforementioned property include the thermoset rubbers. However, several varieties of injection-moldable thermoplastic elastomer products are now replacing conventional rubbers. TPEs can also be used to alter the properties of firm and inflexible thermoplastics to enhance impact strength.
Different Stretch Properties of TPE
Before discussing about the properties of TPE, it’s important to know about the tensile properties. Tensile properties refer to the measurements used to ascertain how an elastomer product functions when pulled or stretched. Here are some of the commonly used testing methods to indicate how well a TPE would function in end-use environments:
Tear Strength: When you use elastomers, you should know how much resistance the product has against tearing. For measuring this, the test bar is notched on one side. This offers a propagation point. You can stretch the material and note the amount of pressure with which the test bar breaks. The units are usually in kiloNewtons per meter (kN/m) or in per square inch (psi).
Tensile at Break: You can test TPEs by pulling and stretching an elastomer until it snaps. When you test the tensile at break value, the amount of pressure or force employed to break it should be measured. The units are in megaPascals (Mpa) or psi. Elastomeric products with better tensile properties is harder to break by pulling than those with lesser values on the test.
Elongation at Break: This value is not about how easy or difficult it is to stretch the material. It’s about how far the material can be stretched before it snaps. This is described as the percentage of the actual length of the material. A few of the soft elastomers can be stretched to more than 1000 percent of their actual length before they snap or break. This implies that a soft elastomeric TPE will have a much higher value than an inflexible or hard material.
Tensile Modulus: In this particular test, the elastomer is pulled and resistivity to the stretching is calculated over a range of different elongation points. This is frequently described as tensile at different percentages of the actual length of an elastomer product. Initially, an elastomer may be resistive to stretching, but will gradually become delicate as the material is elongated. This is also known as ‘necking’.
Do TPEs have a service temperature? When it comes to the term ‘service temperature’, it generally refers to the highest temperature at which a material becomes suitable for use. It depends on a host of factors such as the period of exposure, performance requirements, part design and existence of a load. Some of the commonly used techniques of measuring service temperature include Heat Deflection Temperature (HDT), Vicat Softening Temperature, Half Tensile Strength, Underwriter’s Laboratory (UL) or any other proprietary methods based on the industry.
What are the applications that require higher service temperatures? Well, they are hydraulic hoses, mining cables and automotive or transportation. The applications that don’t require high service temperature are the commonly used indoor applications like kitchenware, grips on personal care items, toys and telephone cords.
Choose thermoplastic elastomer products based on your requirements and the quality, properties, service temperature of the particular material. If you are not sure, consult a supplier dealing with elastomers. Explain your requirements as thoroughly as you can so that you can get an optimum solution.