Pressure sensitive adhesives based on epoxidized soybean oil: correlation between curing conditions and rheological properties

Abstract

Renewable resources, including vegetable oils, can be used as feedstock for the manufacture of pressure sensitive adhesives (PSA) that can compete with those derived from petrochemical sources, but with the environmental benefit of being sustainable. Completely bio-based PSA with tunable viscoelastic properties were synthesized from mixtures of epoxidized soybean oil and sebacic acid by a solvent-free one-step reaction, in the absence of catalyst. Curing conditions and pot-life were determined for formulations with stoichiometric acid/epoxy ratio. Curing time ranged from the gel point (tgel) to tgel + 30 min at the selected temperature (170 °C) to study the correlation between the reaction, rheological behavior, and potential adhesive performance. These renewable PSA can be tailored by controlling the curing parameters according to the desired application, since the rheological profile and gel content were greatly dependent on the curing conditions. In particular, the obtained adhesives cured at 170 °C between 65 and 75 min showed the best balance between tack and cohesion.