Asphalt modified with an sbs/mmwcnt nanocomposite and production method thereof

Abstract

The invention relates to a method for modifying an asphalt binder using, as an additive, a nanocomposite of: functionalized multi-walled carbon nanotubes dispersed in a styrene-butadiene-styrene polymer matrix (SBS/MMWCNT). The asphalt modified with the SBS/MMWCNT nanocomposite has substantially improved mechanical resistance to deformations and to loads at high temperatures, such that the life of the flexible paving is improved. The asphalt mixtures produced with this novel modified asphalt binder have considerably less rutting, are classified as high-modulus asphalt mixtures when produced from asphalt of medium (60/70) or greater hardness, and are not sensitive to moisture effects.

1 . A polymer nanocomposite comprising styrene-butadiene-styrene and multi-walled carbon nanotubes obtained by the process comprising:
 a) dispersing a multi-walled carbon nanotubes in a solvent by ultrasound and/or mechanical stirring in order to obtain a multi-walled carbon nanotubes dispersion;   b) dissolving a styrene-butadiene-styrene polymer in a solvent by mechanical stirring in order to obtain a styrene-butadiene-styrene solution;   c) mixing the multi-walled carbon nanotubes dispersion with the styrene-butadiene-styrene solution by ultrasound and/or mechanical stirring and obtaining a homogeneous viscous solution of styrene-butadiene-styrene polymer and multi-walled carbon nanotubes;   d) evaporating the solvent from the homogeneous viscous solution of styrene-butadiene-styrene polymer and multi-walled carbon nanotubes.   
     
     
         2 . The polymer nanocomposite of  claim 1 , wherein the multi-walled carbon nanotubes are functionalized with functional groups selected from the group consisting of hydroxyl groups, carboxylic acid groups, amino groups, phenol, and alkyl groups. 
     
     
         3 . The polymer nanocomposite of  claim 1 , wherein the styrene-butadiene-styrene polymer is in the form of pellets or crumbs. 
     
     
         4 . The polymer nanocomposite of  claim 1 , wherein the solvent is selected from the group consisting of xylenes, toluene, acetone, tetrahydrofuran, chloroform, cyclohexane, ethanol, methanol, propanol, dimethylformamide, and combinations thereof. 
     
     
         5 . The polymer nanocomposite of  claim 1 , wherein a solvent/polymer weight ratio is between 1 and 20. 
     
     
         6 . The polymer nanocomposite of  claim 1 , wherein a solvent/multi-walled carbon nanotubes weight ratio is between 10 and 10,000. 
     
     
         7 . The polymer nanocomposite of  claim 1 , wherein the multi-walled carbon nanotubes have a diameter between 5-50 nm and a length between 1-30 μm. 
     
     
         8 . The polymer nanocomposite of  claim 1 , wherein the styrene-butadiene-styrene solution and the multi-walled carbon nanotubes dispersion are mixed and homogenized for a period of not greater than 4 hours. 
     
     
         9 . The polymer nanocomposite of  claim 1 , wherein the solutions prepared from styrene-butadiene-styrene and multi-walled carbon nanotubes are mixed by means of ultrasound and/or mechanical stirring until they are homogenized. 
     
     
         10 . The polymer nanocomposite of  claim 1 , wherein the solvent is evaporated from the homogenized solution by means of a rotary evaporator, a dryer, an evaporator, a vacuum distillation system or any other means that allows the evaporation of the solvent until the solution becomes viscous. 
     
     
         11 . The polymer nanocomposite of  claim 1 , wherein sheets of the polymer nanocomposite are obtained and cut to pieces having a maximum size of 0.2 cm-4 cm. 
     
     
         12 . The polymer nanocomposite of  claim 1 , wherein the styrene-butadiene-styrene polymer is of radial or linear structure.