a polyamide p 1 and a polyolefin po 1 having a p 1 polyamide matrix optionally a layer formed from evoh a layer formed from a blend of pa 6 12 copolyamides one comprising by weight more 6 than 12 and the other more 12 than 6 a layer formed from a polyamide p 3 it being possible for p 1 and p 3 to be identical or different the layers and being successive and adhering to one another in their respective contact regions application_number US 97840804 A description with regard to the polyamide p 1 or p 1 a matrix of the layer 1 or 1a it is possible to use any polyamide the term lt lt polyamide gt gt is understood to mean products resulting from the condensation of one or more amino acids such as aminocaproic 7 aminoheptanoic 11 aminoundecanoic and 12 amino dodecanoic acids or of one or more lactams such as caprolactam oenantholactam and lauryllactam of one or more salts or mixtures of diamines such as hexamethylenediamine dodecamethylenediamine metaxylylenediamine bis p aminocyclohexyl methane and trimethylhexamethylenediamine with diacids such as isophthalic terephthalic adipic azelaic suberic sebacic and dodecanedicarboxylic acids aliphatic diamines are u03b1 u03c9 diamines containing between the amino terminal groups at least 6 carbon atoms preferably 6 to 10 carbon atoms the carbon chain may be linear polymethylenediamine or branched or even cycloaliphatic preferred diamines are hexamethylenediamine hmda dodecamethylenediamine and decamethylenediamine the dicarboxylic acids may be aliphatic cycloaliphatic or aromatic the aliphatic dicarboxylic acids are u03b1 u03c9 dicarboxylic acids having at least 4 preferably at least 6 carbon atoms excluding the carbon atoms of the carboxylic groups in the linear or branched carbon chain the diacids are azelaic sebacic and 1 12 dodecanoic acids as an illustration of such.