We live in a world of plastics, but not all plastics are created equal. Some are brittle and prone to cracking, while others are flexible and resilient. Enter TPE, or thermoplastic elastomer, a remarkable material that’s changing the game, making plastics tougher, more versatile, and more adaptable to a wide range of applications.
The Power of Blending:
TPEs are essentially blends of different polymers, combining the best of both worlds. Two popular types of TPEs are TPO and POE. TPO, or thermoplastic polyolefin, is a blend of rubber and polyolefins, while POE, or polyolefin elastomer, is a blend of α-olefins and polyolefin resins. These blends create materials with unique properties that make them ideal for a wide range of applications.
TPO: The Tough and Resilient Choice:
TPO is known for its toughness, resilience, and excellent compatibility with polyolefins. It’s often used in automotive applications, where it provides impact resistance, weather resistance, and heat resistance. Think of the dashboards, bumpers, and door panels in your car – chances are they’re made with TPO.
POE: The Flexible and Versatile Option:
POE, on the other hand, is known for its flexibility, high impact strength, and excellent compatibility with polyolefins. It’s often used in applications where flexibility and durability are key, such as wire and cable insulation, sporting goods, and medical devices.
The Future of TPE:
The future of TPE is bright, with ongoing research and development focused on enhancing its properties and expanding its applications. New blends, additives, and processing techniques are constantly being developed, leading to even tougher, more versatile, and more sustainable TPE materials.
TPE is a game-changer for the plastics industry, offering a way to create stronger, more durable, and more versatile materials. From automotive parts to medical devices, TPE is making a difference, making our lives safer, more comfortable, and more sustainable. So, the next time you encounter a product made with TPE, remember the remarkable properties of this versatile material and its potential to create a better future.
Olefin thermoplastic elastomer TPE includes two types: TPO and TPV (Thermoplastic Vulcanizate). Thermoplastic polyolefin elastomer (TPO) is a blend composed of soft segment (more than 20%) rubber and hard segment polyolefin.
Usually the rubber components are ethylene propylene diene rubber (EPDM), nitrile rubber (NBR), butyl rubber (IIR) and natural rubber (NR); the polyolefin components are mainly polypropylene (PP) and polyethylene (PE). ). Currently, the blend of EPDM and PP that is used more often is also called modified polypropylene or modified polyethylene.
The vulcanized elastomer after TPO vulcanization is called TPV. It is a thermoplastic polyolefin elastomer that is inseparable and complementary to TPO and is the main development trend of TPO in the future.
The main varieties and characteristics of polyolefin elastomers used for modified plastics:
1. Polyolefin thermoplastic elastomer
1. Ethylene-α olefin copolymer, propylene-α olefin copolymer, 1-butene homopolymer and copolymer, propylene-α olefin copolymer (metallocene catalysis)
①Amorphous or partially crystalline polyolefins still have good flexibility even at low temperatures;
②Colorless and transparent, the refractive index is not significantly different from other olefins, and the transparency of the new variety does not decrease;
③ It has good affinity with various polyolefins and can be molded under dry mixing conditions;
④ It has good uniformity, and there is no gel or glue lumps when the film is formed;
⑤Same as PE and PP, it has good heat aging resistance and weather resistance. After using metallocene catalysts, compared with XR, the molecular weight distribution is uniform, has a low melting point of 25°C to 35°C, and has good heat sealing properties to prevent adhesion.
2. Ethylene, 12-octene copolymer (EOM)
①Low crystallinity, with flexibility, rubber elasticity, compression permanent deformation, heat resistance, transparency and other properties;
②Using internal catalytic technology, a uniform molecular structure can be obtained;
③ It can graft long macromolecule chains onto the molecular main chain and has properties such as melt tension;
④ It can be well dispersed in PP. As a TPO impact-resistant modified material, the production cost is lower than EPDM.
3. Ethylene, 2-butene copolymer
① Improve process performance by expanding the molecular weight distribution range;
② By controlling the molecular weight of the grafted long chain, the melt tension is increased, and the melt destructiveness and extrusion swellability are improved. Maintains its mechanical properties;
③Due to the mechanical properties of the linear structure of new products with high molecular weight and high viscosity, the melt viscosity is increased.
2. Performance and scope of use of polyolefin elastomer POE
POE is a polymer blend composed of octene and polyolefin resin. The continuous phase and dispersed phase present two-phase separation. Images from scanning electron microscopes or phase contrast microscopes show that it can form rubber as the continuous phase and resin as the dispersed phase. The phase may be rubber as the dispersed phase, resin as the continuous phase, or both present an interpenetrating network structure when the continuous phase is present. As the phase state changes, the properties of the blend also change.
If the rubber is a continuous phase, its performance is similar to that of vulcanized rubber; when the resin is a continuous phase, its performance is close to that of plastic.
3. Processing and Cooperation
POE does not require mixing and vulcanization. Common thermoplastic processing equipment can be used for processing and molding. The molding processing temperature and processing pressure should generally be slightly higher and can be processed at extremely high processing speeds. It can be injection molded, extruded, or processed into sheets or films using a calender, and can be blow molded. Products with complex shapes can be manufactured using thermoforming.
Various pigments can be added to make different colors as needed. Some manufacturers provide various grades of special batching materials according to the use requirements of the products, such as oil-resistant, flame-retardant, electrically stable and electrostatically paintable types.
Sometimes in order to improve the processing performance and performance of certain products or reduce costs, certain compounding agents, such as antioxidants, softeners, fillers, colorants, etc., can also be added. Offcuts and scraps can be recycled and reused. However, the general blending ratio does not exceed 30%, which has no impact on the performance and the impact of POE on the blending system.
POE is a thermoplastic elastomer that uses metallocene catalysts to achieve in-situ polymerization of ethylene and octene. Its characteristics are:
- Octene’s soft chain curl structure and crystallized ethylene chains serve as physical cross-linking points, giving it both excellent toughness and good processability.
- POE has no unsaturated double bonds in its molecular structure and has excellent aging resistance.
- POE has a narrow molecular weight distribution, good fluidity, and good compatibility with polyolefins.
- Good fluidity can improve the dispersion effect of fillers and also improve the weld line strength of products.
As the POE content increases, the impact strength and elongation at break of the system are greatly improved. It can be seen that POE has excellent toughening effect on PP and has good compatibility with PP and activated calcium carbonate.
This is because POE has a narrow molecular weight distribution, and the lateral octyl groups in the molecular structure are longer than the lateral ethyl groups. They can form connecting points in the molecular structure, which play a connecting and buffering role between the components, allowing the system to disperse and disperse when impacted. The function of buffering impact energy reduces the chance of silver cracks developing into cracks due to stress, thus improving the impact strength of the system.
When the system is subjected to tension, the network structure formed by these connecting points can undergo large deformation, so the elongation at break of the system increases significantly. When the POE content increases, the tensile strength, bending strength and bending strength of the system increase. The strength and flexural modulus have both decreased, which is determined by the properties of POE itself, so the POE content should be controlled below 20%.
The relationship between POE content and melt index. After adding POE, the melt index of the system increases. POE itself has good fluidity. Its addition also improves the fluidity of the entire system. When the POE content exceeds 15 parts, the melt index of the system basically does not change. If you want to continue to improve the fluidity of the system, you cannot completely Depends on POE.
Basic features
- POE has the general physical properties of thermoplastic elastomers, such as formability, waste recycling and vulcanized rubber properties.
- The price is low, and the relative density is small, so the volume is cheap.
- It has excellent heat resistance and cold resistance and has a wide range of uses.
- Good weather resistance and aging resistance.
- Oil resistance, resistance to compression set and wear resistance are not very good.
Application scope
It is mainly used to modify and toughen PP, PE and PA in the automobile industry to make bumpers, fenders, steering wheels, pads, etc. In the wire and cable industry, the insulation layer and sheath require high heat resistance and environmental resistance. Also used in industrial products such as hoses, conveyor belts, tapes and molded products. Medical equipment, household appliances, cultural and sports supplies, toys, etc., as well as packaging films, etc.