Common Blending Components of SEBS And Their Effects on Properties

SEBS (Styrene-Ethylene-Butylene-Styrene) is often called the “golden rubber” due to its outstanding weather resistance, aging resistance, recyclability, and the fact that it does not require traditional vulcanization. It has been widely applied in automotive, wire & cable, medical devices, electronics, packaging and many other fields.

However, SEBS is rarely used alone. It usually needs to be blended with other components to optimize processing behavior, cost efficiency, and mechanical properties. Below are the most common compounding ingredients and their effects:

1. Plasticizer Oils (Paraffinic Oil, Naphthenic Oil)

Functions

• Improve processability: reduce melt viscosity and energy consumption.

• Lower cost: act as an extender to reduce SEBS dosage.

Effects on Properties

• Excellent compatibility with the polybutadiene phase of SEBS, but insoluble in the polystyrene phase.

• Can maintain or even enhance phase separation structure, ensuring stable performance.

2. Polypropylene (PP)

Functions

• Compensates for the strength loss caused by excessive oil loading.

• Balances rigidity and toughness.

Effects on Properties

• With increasing PP content: modulus, tensile strength, and hardness rise; elongation at break decreases.

Mechanism

• Works synergistically with the butadiene phase, improving elastic domain volume but reducing extensibility due to higher rigidity.

3. Polystyrene (PS)

Functions

• Provides reinforcement, increasing rigidity and dimensional stability.

Effects on Properties

• With increasing PS content: modulus and hardness rise; elongation at break decreases.

• Tensile strength first decreases, then increases significantly when PS exceeds 60 parts, due to strong reinforcing effects.

4. Inorganic Fillers (Calcium Carbonate Series)

Functions

• Cost-effective method to adjust hardness and stiffness.

Effects on Properties

• Increases hardness and modulus, but lowers tensile strength.

• Nano-CaCO₃ provides the best performance improvement but at higher cost.

• Ground/light CaCO₃ offers a more economical alternative.

Mechanism

• Enhances rigidity and hardness, but disrupts the elastomeric network, reducing toughness.

Conclusion

In SEBS compounding, selecting the right plasticizer oil, PP, PS, and inorganic fillers enables manufacturers to balance cost, hardness, strength, and toughness.

At TOLL, we supply a wide range of SEBS grades and provide technical support to help our partners optimize formulations and applications. For raw material inquiries or technical consultation, feel free to contact us anytime.