How to Choose SBS Molecular Weight, Structure, and Styrene Content for the Best Cost-Performance in Toughening Recycled PS

SBS (Styrene-Butadiene-Styrene) is an effective toughening agent for recycled PS, addressing its inherent brittleness while maintaining processability. To balance performance and cost, here are key principles for selection:

Molecular Weight Control: Optimal range is 80,000–200,000.

• Below 80,000: SBS tends to precipitate in recycled PS, forming weak networks and showing minimal impact resistance improvement.

• Above 200,000: Melt viscosity rises sharply, causing extrusion and injection molding issues such as melt fracture and poor part formation.

Styrene Content Optimization: Keep 30%–40%.

• <30%: Poor compatibility with PS matrix, leading to phase separation.

• 40%: Reduced elastic soft segment, weakening toughening effect.

Structure Type: Prefer linear SBS.

• Linear SBS offers better dispersion, adapting well to recycled PS with impurities or wide molecular distribution.

• Star-shaped SBS, though offering higher impact strength, disperses less easily and is only suited for special applications like low-temperature impact-resistant packaging.

Addition Amount: Recommended 8%–15%.

• <8%: Incomplete network, limited improvement.

• 15%: Loss of rigidity and heat resistance, plus higher cost.

Comparison with EVA:

• EVA is cheaper, but its toughening effect is weaker.

• EVA reduces rigidity and heat resistance, limiting high-temperature use.

• At high dosage, EVA also causes processing instability.

We provide a range of SBS grades at competitive prices. If you need raw materials or have technical questions, feel free to contact our service engineers.