TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The inherent viscosity of the copolyamide is 0.5-2, preferably 0.8-1.8. (A) comprises: 0.5-0.7 mole of X/1 mole of Y1 (or 1 mole of Ar1); 10.10/10.T and X are the proportions of 0.5 mole/1 mole of Y1 and 1 mole/0.05 mole of Y1; and 11/10.T resulting from the condensation of aminoundecanoic acid, 1,10-decanediamine and terephthalic acid, 12/12.T resulting from the condensation of lactam 12, 1,12-dodecanediamine and terephthalic acid or 10.1/10.T resulting from the condensation of isophthalic acid, 1,10-decanediamine and terephthalic acid. The structure comprises: an outer layer consisting of aliphatic polyamide, polyolefin or a compatibilized mixture of aliphatic polyamide and polyolefin, optionally a binder layer and an inner layer made of the composition; the outer layer, optionally a binder layer, a central layer consisting of the composition, optionally a binder layer, an inner layer, optionally conductive layer consisting of aliphatic polyamide, polyolefin or a compatibilized mixture of aliphatic polyamide and polyolefin, and optionally, a conductive layer of aliphatic polyamide or mixture of aliphatic polyamide and polyolefin; an outer layer consisting of the composition, optionally a binder layer, an inner layer and optionally the conductive layer; the outer layer, optionally a layer of aliphatic polyamide or a mixture of aliphatic polyamide and polyolefin, optionally a binder layer, a middle layer made of a barrier material comprising ethylene vinyl-alcohol, fluorinated polymers, polyphenylene sulfide, polybutylene naphthalates, an aliphatic polyketone, polyarylamide (PA-MXD6), liquid crystal polymer, nanocomposites polymers and an alloy having a matrix of such materials, optionally a binder layer, an inner layer, and optionally, the conductive layer; the outer layer, optionally a layer of aliphatic polyamide or a mixture of aliphatic polyamide and polyolefin, optionally a binder layer and the inner layer; or the outer layer, optionally a binder layer, the middle layer, optionally a binder layer and the inner layer. Preferred Definitions:    Ar1 = terephthalic acid; and    Y1 = 9-14C alpha omega diamine, preferably 1,10-decanediamine.