Asphalt composition containing highly coupled radial polymers

Abstract

A bituminous composition comprising a compatible bituminous component and a completely non-tapered radial block copolymer of a conjugated diolefin and a vinyl aromatic hydrocarbon wherein the polymer has from 3 to 6 arms, a molecular weight of from 150,000 to 400,000, a coupling efficiency of at least 95 percent, and a polyvinyl aromatic hydrocarbon blockiness of at least 98.5%.

I claim: 
     
       1. A bituminous composition comprising a compatible bituminous component and a completely non-tapered radial block copolymer of a conjugated diolefin and a vinyl aromatic hydrocarbon wherein the block copolymer has from 3 to 6 arms, a molecular weight of from 150,000 to 400,000, a coupling efficiency of at least 95 percent, and at least 98.5% of the vinyl aromatic hydrocarbon is contained in the vinyl aromatic hydrocarbon blocks. 
     
     
       2. The composition of claim 1 wherein the polymer comprises from 8 parts to 15 parts by weight of the bituminous composition. 
     
     
       3. The composition of claim 1 wherein the polymer is hydrogenated. 
     
     
       4. A hot melt asphalt concrete composition comprising: (a) from 80 parts to 99 parts by weight of aggregate, and   (b) from 1 part to 20 parts by weight of the bituminous composition of claim 1.   
     
     
       5. The hot melt asphalt concrete composition of claim 4 wherein the bituminous composition is comprised of: (a) from 90 parts to 98 parts by weight per 100 parts of the bituminous composition of the bituminous component, and   (b) from 2 parts to 10 parts by weight per 100 parts of the bituminous composition of the polymer.   
     
     
       6. A roll roofing membrane comprising a membrane and the bituminous composition of claim 1. 
     
     
       7. The roll roofing membrane of claim 6 wherein the polymer comprises from 8 to 15 parts per 100 parts by weight of the bituminous composition.