Patent ID: 7717139

Claim:
A method for improving barrier properties of a structure to alcohol-containing fuels comprising: a) forming a structure consisting of the following successive layers which adhere to one another in their respective areas of contact: 1) an outer layer ( 1 ) formed from a polyamide chosen from PA-11 and PA-12; 2) a tie layer ( 2 ) made of one or more copolyamides; 3) an optional layer ( 3 ) formed from an EVOH; 4) an optional a tie layer that does not exist if no layer ( 3 ) is present; and 5) an inner layer ( 4 ) formed from a polyamide/polyolefin blend having a polyamide matrix, containing 0.1 to 10% carbon nanotubes per 90 to 99.9% polyamide/polyolefin blend, wherein said carbon nanotubes are tubes or hollow fibres having a diameter of about 5 to 20 nanometers (nm) and a length of 100 to 1000 times the diameter, wherein said polyamide portion of the polyamide/polyolefin blend is from 40 to 75 percent by weight of said blend, and the polyolefin portion of the polyamide/polyolefin blend is from 25 to 60 percent by weight, and wherein said carbon nanotubes concentrate in the polyamide, wherein said inner layer has both good barrier properties to alcohol-containing fuels and antistatic properties; b) exposing said structure to an alcohol containing fuel.