Styrenic Block Reinforcing Additives in Pressure Sensitive Adhesives

Styrenic block copolymers are one of the most used constituents in pressure sensitive adhesives due to their rubbery, yet viscous nature that allows them to flow out and adhere to substrates and yet have resiliency to resist creep. This study focused on high temperature performance benefits certain styrene-miscible or styrene-associating resins, referred to as styrenic block reinforcing additives (SBRAs), imparted to styrenic-block-copolymer-based pressure sensitive adhesives. The experimental design focused on varying the compositions of the SBRAs to control the glass transition temperatures and plateau moduli and compare results to those predicted by the Einstein, Graessley, and Fox equations. Eight SBRAs, loaded in three different ratios to the styrene fraction, allowed for rheological, shear adhesion failure temperature (SAFT), and peel adhesion testing. Sabic SA-90 poly(phenylene ether) resin, added in a 2.0:1.0 ratio to polystyrene content, provided the highest temperature performance of any SBRA tested, with an increase in the G'(100°C) storage modulus of 160%, a 34°C increase in SAFT, and peel adhesion increased by 50% - all compared to the control with no SBRA.