Hot-melt adhesives with vegetable resins

The study analyzed the effect produced by adding a tackifier of vegetal origin (Grindelia resin) to Ethylene Vinyl Acetate (EVA) copolymers. The adhesives were prepared at laboratory scale and rheological thermal and adhesive properties of the formulations with the base polymer and the natural resins were determined as well as the physical rheological and thermal properties of their components separately. By Differential Scanning Calorimetry good compatibility and miscibility of the systems was found due to the existence of a single glass transition temperature. Flow properties showed that consistency rates decreased with increasing temperature for Grindelia resin. The storage and loss modules (G'' and G'''') determined that the cross temperature decreased as the percentage of tackifier increased evidencing a temperature shift in the passage from elastic solid to viscous liquid. The results obtained from the characterization of the EVA/tackifier mixtures imply that they can be used in the packaging industry considering grindelia resin as a replacement for rosin resin.