Adhesive composition and structure comprising at least one layer of said composition

A polyamide consisting of the following units:

• at least one unit denoted A with a mean number of carbon atoms per nitrogen atom, denoted CA, ranging from 4 to 8.5;
• at least one unit denoted B with a mean number of carbon atoms per nitrogen atom, denoted CB, ranging from 7 to 10;
• at least one unit denoted C with a mean number of carbon atoms per nitrogen atom, denoted CC, ranging from 9 to 18;
• and
• optionally at least one unit Z other than an amide unit;
• one of the units A, B or C being in very predominant proportion in the polyamide and representing from 80% to 97% by weight relative to the total weight of the polyamide,
• the mean number of carbon atoms per nitrogen atom of the units A, B and C also corresponding to the following strict inequality:
• CA<CB<CC,
• the heat of fusion of the polyamide being greater than 25 J/g (DSC),
• the melting point of the polyamide being greater than 150° C. (DSC), and
• wherein unit B is the very predominant unit in the polyamide.