Viscoelastic behavior of pressure-sensitive adhesive based on block copolymer and kraft lignin

Practical adhesion of pressure-sensitive adhesives (PSAs) is strongly dependent on their viscoelastic properties. The use of biobased materials emerged as an effective approach to modify the rheological, mechanical, and adhesive properties of PSAs. The biopolymer kraft lignin (KL), a by-product of pulp and paper manufacturing, appeared as a potential candidate for modifying the adhesive behavior of PSAs. In this study, we developed a block copolymer-based PSA by incorporating a hydrocarbon resin (HCR) and kraft lignin into the block copolymer polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS). "Viscoelastic windows", which describe the potential application of a PSA based on its viscoelastic behavior, were constructed for PSAs with the addition of KL. These results demonstrate the potential for application as a high-shear PSA due to the increased energy dissipation of the samples. Practical adhesion was evaluated using probe tack tests and lap shear strength measurements, which effectively demonstrated an increase in the cohesive strength of the PSA with an optimized concentration of 5 wt% KL.