Unveiling coumarone resin as a tackifier in SBS-based PSA systems—a comprehensive viscoelasticity study

Styrene–butadiene–styrene (SBS) is an attractive block copolymer for Pressure Sensitive Adhesives (PSA) for labels, tapes, and hygiene products due to its good tack and easy processability. A key challenge in PSA formulation is overcoming the inherent trade-off between adhesion (tack) and cohesion (shear strength). This study is aimed to explore the potential of coumarone resin as a dual-phase tackifier for SBS based PSA. Owing to its aromatic structure and flexible side groups, cumarone-SBS blend offers a unique viscoelastic spectrum. Our findings confirmed strong resin–polymer compatibility and improved thermal stability. Rheological studies further showed that SBS formulations with coumarone develop a broader viscoelastic plateau and achieve a well-balanced relationship between elasticity (G′) and viscosity (G″) across frequencies relevant to PSA applications. Optimal formulation satisfies the Dahlquist criterion, achieving maximum peel strength (∼27 N/25 mm) and SAFT (∼70 °C), thus enabling tailored, cost-effective removable PSA.