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Polymers most commonly used for asphalt modification were not specifically designed for this purpose. They were intended for use in adhesives, as plastic additives and for molding and extruding rubber goods. They are typically not very soluble in asphalt and a lot of energy is required to disperse them. In addition, the density of the polymer is usually lower than the density of the asphalt, so even after thorough digestion, the polymer may separate over time, usually by floating to the surface.

The problem is overcome by chemically reacting the polymer and the asphalt so that they can no longer separate. Using this chemical technology we can create a permanent chemical bond between the polymer and the asphalt. This will cross-link the asphalt and the polymer.

The Butaphalt® Reactants are very powerful cross-linking agents developed by SemMaterialsSM. They are very efficient – useful at levels of 0.05 to 0.1% of the weight of the polymer modified asphalt – very easy to use and fast acting. The chemical reaction between the polymer and the asphalt in the presence of Butaphalt® Reactants is usually 95% complete within four hours. It is also permanent SBS modified asphalt chemically reacted with Butaphalt® Reactants can be stored virtually indefinitely and is routinely stored over a winter with no ill effects.

Among the benefits obtained by the use of Butaphalt® Reactants are:

• More efficient use of polymer or reduced polymer loading
• Drastically reduced polymer separation
• Reduced aging
• Improved storage stability
• Improved high and low temperature performance
• Reduced sensitivity to base asphalt