Kraton polymers are blended with plastics such as styrenics, polyolefins, and engineering thermoplastics to improve performance, particularly impact, by toughening these plastics at low or room temperatures. Depending on application needs, either transparent or non-transparent solutions can be offered. These polymers help compatibilize different plastics to bring out the best in each material, enhance the impact strength of scrap or regrind materials, and improve processability to allow for higher filler or reinforcement loadings.
Polymer Modification Applications
Kraton polystyrene end blocks offer exceptional compatibility with crystal polystyrene and high-impact polystyrene (HIPS), making them excellent impact modifiers, particularly for low-temperature applications like food packaging.
Regarding non-transparent applications, USBC polymers such as Kraton™ D1101, Kraton™ D1102, Kraton™ D1155, and Kraton™ D1157 can be used. Among these, Kraton D1101 stands out for its superior impact strength, while Kraton D1102 is favored for its ease of processing, especially when using mild shear rate compounding equipment such as single screws. For upgrading recycled polystyrene and high-impact polystyrene from the waste stream, Kraton D1155, and CirKular+™ C3000 are the preferred products.
Unmodified polypropylene homopolymer (hPP) is known for its high rigidity and excellent heat resistance, but unfortunately, it falls short in impact resistance, especially at low temperatures. However, combining hPP with Kraton polymers significantly improves toughness at room and low temperatures.
Regarding impact-modified PP, a fine balance is required between high flow, high stiffness (modulus), and excellent impact performance. While PP offers high melt flow (> 30g/10 min.), it’s often necessary to incorporate talc, silica, or other natural fillers to increase stiffness (modulus). That’s where Kraton polymers come in, as they can help to enhance impact strength for use in thin-walled part designs such as automotive instrument panels and exterior bumper systems.
For non-transparent applications, low molecular weight grades supplied in dense pellet form are recommended. This helps to achieve a homogeneously dispersed blend composition, ensuring optimal results. Various Kraton HSBC products provide a best-in-class balance of flow, modulus, and impact strength in combination with talc-filled PP copolymer blends. Moreover, Kraton HSBC polymers deliver excellent weatherability and heat-aging performance.
Kraton enhanced rubber segment (ERS) is the ideal solution to modify random copolymer PP to improve transparency. These products are delivered in dense pellet form, ensuring easy handling and mixing. Kraton ERS polymers can be sterilized by steam, EO, EB, or gamma radiation, and they meet the most stringent food and medical regulations.
CirKular+™ Performance Enhancement Series is a versatile multi-resin compatibilizer designed to enhance the performance of recycled PP and polyolefinic blends across various applications.
Kraton polymers are suitable for tubing, film, sheet, and injection-molded products. Contact a Kraton Sales Representative for specific grade recommendations to achieve the best formulation and performance results.
Kraton offers a range of hydrogenated styrenic block copolymers (HSBC) that are functionalized to improve compatibility with polar engineering thermoplastics (ETP) like polyamides (PA) and high-temperature polyamides (HTPA). These maleated SEBS block copolymers act as effective modifiers for toughening various polyamide chemistries. Their saturated rubber midblock enables them to withstand ETP processing conditions while delivering good weatherability and heat aging performance. For recycled polyamide and nylon streams, CirKular+™ Compatibilization Series is a high-performance multi-resin compatibilizer.
Kraton polymers are compatible and effective impact modifiers for polyphenylene ether (PPE). Like polystyrene, the higher molecular weight styrenic block copolymers (SBC) are especially effective at toughening PPE and providing a unique microstructure. Kraton™ G1651, Kraton™ G1654, Kraton™ G1650, Kraton™ G1701, and Kraton™ A1536, or a blend thereof, are highly recommended for applications where heat aging performance, weatherability, and limited degradation during processing are critical.
Polycarbonate is known for its exceptional toughness, but thicker parts (6.4 mm) can be prone to brittleness and have lower notched Izod values (125 J/m) compared to thinner parts (3.2 mm) which can achieve notched Izod values up to 950 J/m at room temperature. To address this issue, Kraton™ G 1651 polymer can be added to the material at just 5 percent, significantly increasing notched Izod (6.4 mm) by a factor of six at room temperature, effectively toughening the thick polycarbonate parts.
Thermoplastic Polyester Elastomer
Thermoplastic polyester elastomer (TPE-E), or COPE or TPC-ET, boasts impressive low-temperature impact strength, chemical resistance, and heat aging performance. However, the material is limited by its hardness. Kraton™ A polymers were specifically designed to address this limitation. These polymers are compatible with TPE-E and improve isotropic properties, making them ideal for manufacturing very thin parts via injection molding. Compared to traditional Kraton HSBC, Kraton A polymers exhibit greater polarity, resulting in superior dispersion of fillers and color concentrates in such compositions. For the ultimate in TPE-E formulation hardness reduction, look no further than the ultra-high flow Kraton™ MD6951 grade.
Compatibilizer and Impact Modifier
In today’s world, plastics are being used in increasingly challenging applications. To meet the specific demands of these applications, plastics are designed and engineered using a combination of polymer types. Kraton styrenic block copolymers (SBC) offer a versatile solution for modifying various resin combinations, serving as both a compatibilizer and an impact modifier for virgin, bioplastics, and recycled resins. Our CirKular+ product line has been specially developed to meet the needs of a wide range of recycled streams.
Features & Benefits
- Polyolefins/Polystyrene or PPE
- Polyamide/Polystyrene or PPE