Views:1 Author:Site Editor Publish Time: 2021-04-06 Origin:Site
The formal definition of thermoplastic rubber or elastomer (TPE) is "a polymer mixture or compound that exhibits thermoplastic characteristics above its melting temperature, enabling it to be formed into products with tpe rubber granules extruder, and within its design temperature range, having an elastomer features, no cross-linking during the manufacturing process. This process is reversible, and the product can be reprocessed and reshaped.
The following knowledge points are listed below:
The properties of TPE extruder
Grades available in the TPE industry
Even though thermoplastic elastomers are thermoplastic, they exhibit elasticity similar to crosslinked rubber. A key indicator is their softness or hardness value measured on the Shore hardness tester scale. Like cross-linked rubber, thermoplastic elastomers can be used as very soft gel materials, ranging from 20 Shore OO to 90 Shore A. At this point, they enter the Shore D scale and can be formulated to a hardness value of up to 85 Shore D, which means the material is very hard.
Since thermoplastic elastomers can be processed on plastic machinery, their cost may be greatly reduced, so designers are increasingly using thermoplastic elastomers. Traditional rubber, whether it is natural rubber or synthetic rubber, is a thermosetting material, which must undergo a chemical cross-linking reaction during the molding or extrusion process, usually called vulcanization or vulcanization. Due to this reaction, it usually cannot be processed in standard thermoplastic equipment. The time required for the completion of the vulcanization reaction is affected by many factors, but it is usually between 1 minute and several hours. On the other hand, the thermoplastic molding and extrusion process for thermoplastic elastomers avoids the crosslinking step and can achieve very fast cycle times, as short as 20 seconds. Environmental and cost pressures require more and more materials to be recyclable. TPE granules extruding machine processing waste, scrap or end-of-life products can be easily reprocessed, and most thermoset elastomers will eventually be used as reclamation materials.
Compared with thermoplastic elastomers, thermoplastic elastomers have excellent colorability and lower density.
There are seven major thermoplastic elastomers on the market, and they are arranged in roughly ascending order:
SBS is based on a two-phase block copolymer with hard and soft segments. The styrene end blocks provide thermoplastic properties, and the butadiene middle blocks provide elastomer properties. SBS may be the TPE-S material with the highest production volume.
It is commonly used in footwear, adhesives, asphalt modification, and lower specifications of seals and handles, where chemical resistance and aging resistance are low. SBS becomes SEBS during hydrogenation.
Because the C=C bond in the butadiene component is eliminated to generate ethylene and butene mid-blocks, it is referred to as SEBS. SEBS is characterized by greatly improved heat resistance, mechanical properties and chemical resistance. Monprene®Tekron® and Elexar® products from Teknor Apex are good examples of hydrogenated styrene block copolymers.
These materials are a mixture of polypropylene (PP) and uncrosslinked EPDM rubber. In some cases, low crosslinking can improve heat resistance and compression set performance. They are used in applications that require higher toughness than traditional PP copolymers, such as car bumpers and dashboards. Performance is limited to the high end of the hardness scale, usually >80 Shore A, and elastomer performance is limited.
In the past, these products were mechanical blends of two polymers. Teknor Apex's Telcar® is an example of this type of TPE-O. However, with new catalyst technology, it is now possible to mix EPDM rubber and polypropylene in the reactor, so these types of thermoplastic elastomers are now available from major polymer manufacturers. These products are suitable for high-volume, low-cost applications, but there is still a market for customized mechanical hybrid TPE-O
These materials are the next advancement in TPE-O performance. These materials are also compounding of PP and EPDM rubber, but they have been dynamically vulcanized during the compounding step.
In automotive seals, tube seals, and other applications that require heat resistance up to 120 degrees Celsius, the replacement of EPDM is growing strongly. The Shore hardness value is usually between 45A and 45D.
Teknor Apex's Uniprene® series is a good example of TPE-V materials, which can be selected from Shore hardness a to Shore hardness 50. Compared with standard TPE-V materials, Uniprene XL increases the upper temperature limit to 140 degrees Celsius and greatly improves the long-term compression and permanent deformation performance.
Many new thermoplastic elastomers are being introduced, called "super thermoplastic elastomers". They are a mixture of engineering plastics and high-performance elastomers, which can greatly improve heat resistance and chemical resistance.
These materials can be based on polyester or polyether polyurethane types, and are used in applications that require excellent tear strength, abrasion resistance and bending fatigue resistance. Such as shoe soles, industrial belts, ski boots, wires and cables. Hardness is limited to the high end of the Shore A scale, usually >80 Shore A.
It is used where it is necessary to increase chemical resistance and heat resistance up to 140 degrees Celsius. They also have good fatigue resistance and tear strength, so they are used in automotive applications such as blow-molded jackets and corrugated pipes, wire and cable, and industrial hose applications. Usually between 75D and 85D.
It is designed for applications requiring higher chemical resistance, especially oil and grease resistance, in which MPR replaces cross-linked nitrile rubber. It also has similar properties to vulcanized rubber in noise reduction applications, and has similar stress relaxation properties.
MPR applications include automotive parts, such as weather strips and handles, which require good adhesion with PVC, polycarbonate or ABS. The compression set value is still much higher than that of thermoset elastomers, so the opportunity to enter the high-performance sealing market is limited.
These products have good heat resistance, chemical resistance and adhesion to polyamide engineering plastics. Their applications include cable jackets and aerospace components.
Now you know what TPE extruder is.