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 (<i>G</i>') and viscosity (<i>G</i>″) 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.