Elastic steric stabilization of polyethylene-asphalt emulsions by using low molecular weight polybutadiene and devulcanized rubber tire

Emulsions containing 3% polyethylene were stabilized against coalescence in an asphalt medium by low molecular weight virgin polybutadiene and recycled styrene-butadiene stabilizers. The recycled styrene-butadiene steric stabilizer precursor was obtained as a thermo-mechanical devulcanized ground rubber tire in asphalt. The low molecular weight butadiene and styrenebutadiene rubbers were in situ reacted with sulfur in order to increase the compatibility of the stabilizer with the asphalt phase.Because of the high molar volume of the asphalt phase and the similarity in contact energy between stabilizer and matrix phase, it is assumed that the stabilization is caused by entropic effects only. The fundamental aspects of elastic stabilization of polyethylene-asphalt emulsions are discussed. The total interaction free energy profile between the polyethylene particles shows that the efficiency of the steric stabilizer formation reaction can be improved significantly.The use of devulcanized rubber tire as a replacement for the virgin polybutadiene precursor in the in situ stabilization process can significantly reduce the cost of the technology.