Polymer Modification

Cariflex Gloves

Kraton® polymers can be blended with many plastics; such as styrenics, polyolefins, and engineering thermoplastics to improve their performance, particularly their impact performance.

Kraton polymers can toughen such plastics both at room and low temperatures and can be clear or opaque depending upon the application. Kraton polymers can help compatibilize dissimilar plastics and bring out the best in each material. They can also revive the impact of scrap or regrind materials.

 

Styrenics

Kraton®s styrene end block products provide good compatibility with crystal polystyrene and high impact polystyrene (HIPS), making them good impact modifiers.

For opaque applications, Kraton D1101, D1102, or D1184 products may be used. D1184 is the most effective grade; however since it has the highest molecular weight; it is the most difficult to process. D1102 has the lowest molecular weight; therefore it is the easiest to process and is often used when only mild shear rate compounding equipment (e.g. single screw) is available.

 

Polypropylene

Unmodified polypropylene (PP) has the advantages of high rigidity and good heat resistance; however it also has poor impact, particularly at low temperatures. Combinations of Kraton® polymer and polypropylene have improved toughness at both room and low temperatures. These combinations can be quite clear.

Many applications areas for impact modified PP require an extreme balance of high flow, high stiffness, and excellent impact performance. In these applications, the PP used is a high melt flow (> 30g/10 min.) and it is often talc filled for stiffness. These combinations are used in thin walled part designs such as automotive instrument panels and exterior bumper systems.

For opaque applications, D1102, G1657, and G1652 are recommended.  D1102 and G1652 are small molecular weight grades and tend to give the best results due to their ability to form a fine dispersion. G1657 provides the best balance of flow, modulus, and impact strength in combinations with talc filled PP copolymer blends. Kraton G polymer should be used in applications that require good weatherability and aging performance.

For clear applications, MD6932 and MD6945 are recommended for use to modify clarified PP. Both products are dense pellets for easy handling and mixing.  When Kraton G polymer is combined with PP it can be steam, EO, EB, or gamma sterilized. Applications for Kraton impact modified PP includes tubing, film, and sheet.

 

Polyamides

To improve compatibility with polar Engineering Thermoplastics (ETP) such as polyamides (PA), Kraton has developed FG1901 and FG1924. These are functionalized block copolymers produced by maleation of an SEBS product. They can be an effective modifier for toughening PA-6 and PA-6.6. The saturated rubber mid block allows them to stand up to ETP processing conditions with heat aging resistance and good weatherability. 

 

Polyphenylene Ether

Kraton® polymers are compatible and effective impact modifiers for Polyphenylene ether (PPE). As in the case for styrenics, the higher molecular weight styrenic block copolymers are more efficient in toughening PPE. Kraton D1184, D1101, and D1102 compounds can be used to impact modify PPE. Caution should be taken to avoid degradation when processing these grades at higher temperatures. If weatherability is important or limiting degradation during processing is critical; G1651, G1654, G1650, G1652, G1701, and G1702 are recommended.

 

Polycarbonate

Polycarbonate (PC) is traditionally thought of as very tough material. Thinner parts (<1/8") can achieve a notched Izod at room temperature in the 18 ft-lb/in range. Thicker parts (1/4" or >) however become brittle with notched Izod of only 2-4 ft-lb/in range. Kraton® G 1651 polymer can be added to PC at 5% to increase the notched Izod 1/4" thick by a factor of six at room temperature.

 

Compatibilizer and Impact Modifier

Many finished products produced today are specialty products designed and engineered to meet certain needs. Most of these products require the use of many different types of polymers to meet the requirements. Kraton® polymers are unique in that they can act as a compatibilizer as well as an impact modifier for various types of resins. This can be applied to virgin and recycled resin. The following are examples of resin systems that can be compatibilized and impact modified with Kraton polymers:

  • Polypropylene / Polystyrene or PPE
  • Polyethylene / Polystyrene or PPE
  • Nylon / Polyethylene or Nylon / Polypropylene
  • Nylon / Polystyrene or PPE
  • Polypropylene / Polyethylene

 

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