Fatty acid diamide, characterized in that it comprises the products derived from a reaction mixture comprising: a) at least one cycloaliphatic diamine comprising a ring of 6 carbon atoms and in particular globally comprising, including the said ring, from 6 to 18 carbon atoms, the said diamine preferably being chosen from: 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane (1,4-BAC), 1,2-bis(aminomethyl)cyclohexane (1,2-BAC) and isomer mixtures thereof, decahydronaphthalenediamines, isophoronediamines, more preferentially 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane (1,4-BAC), and even more preferentially 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), b) a fatty hydroxy acid from 12-hydroxystearic acid (12-HSA), 9-hydroxystearic acid (9-HSA), 10-hydroxystearic acid (10-HSA), 14-hydroxyeicosanoic acid (14-HEA) or binary or ternary or quaternary mixtures thereof, preferably 12-hydroxystearic acid or a binary or ternary mixture of 12-hydroxystearic acid with the other hydroxy acids mentioned, c) at least a second diamine selected from linear primary aliphatic C 2 to C 12, preferably C 2 to C 8 and more preferentially C 2 to C 6 diamines, d) optionally, at least one monoacid selected from saturated and non-hydroxylated linear C 6 to C 18, preferably C 6 to C 15 and more preferentially C 6 to C 12 carboxylic acids, e) optionally, at least a third primary diamine different from c) selected from linear aliphatic C 2 to C 12, preferably C 2 to C 8 and more preferentially C 2 to C 6 diamines, f) at least one aromatic diamine chosen from xylylenediamines, preferably from m-, p-xylylenediamines (m-, p-XDA), more preferentially m-xylylenediamine (m-XDA), the said aromatic diamine possibly being partially replaced with a cycloaliphatic diamine as defined in point a) and in that - the said cycloaliphatic diamine a) is in the presence of at least one aromatic diamine f) chosen from xylylenediamines, - the said diamine a) represents from 50 mol% to 99 mol% of the total number of moles of diamines a) + f) and - the molar percentage of (a+f)/(a+c+e+f) ranges from 30% to 80%. a) at least one cycloaliphatic diamine comprising a ring of 6 carbon atoms and in particular globally comprising, including the said ring, from 6 to 18 carbon atoms, the said diamine preferably being chosen from: 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane (1,4-BAC), 1,2-bis(aminomethyl)cyclohexane (1,2-BAC) and isomer mixtures thereof, decahydronaphthalenediamines, isophoronediamines, more preferentially 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane (1,4-BAC), and even more preferentially 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), b) a fatty hydroxy acid from 12-hydroxystearic acid (12-HSA), 9-hydroxystearic acid (9-HSA), 10-hydroxystearic acid (10-HSA), 14-hydroxyeicosanoic acid (14-HEA) or binary or ternary or quaternary mixtures thereof, preferably 12-hydroxystearic acid or a binary or ternary mixture of 12-hydroxystearic acid with the other hydroxy acids mentioned, c) at least a second diamine selected from linear primary aliphatic C 2 to C 12, preferably C 2 to C 8 and more preferentially C 2 to C 6 diamines, d) optionally, at least one monoacid selected from saturated and non-hydroxylated linear C 6 to C 18, preferably C 6 to C 15 and more preferentially C 6 to C 12 carboxylic acids, e) optionally, at least a third primary diamine different from c) selected from linear aliphatic C 2 to C 12, preferably C 2 to C 8 and more preferentially C 2 to C 6 diamines, f) at least one aromatic diamine chosen from xylylenediamines, preferably from m-, p-xylylenediamines (m-, p-XDA), more preferentially m-xylylenediamine (m-XDA), the said aromatic diamine possibly being partially replaced with a cycloaliphatic diamine as defined in point a) and in that - the said cycloaliphatic diamine a) is in the presence of at least one aromatic diamine f) chosen from xylylenediamines, - the said diamine a) represents from 50 mol% to 99 mol% of the total number of moles of diamines a) + f) and - the molar percentage of (a+f)/(a+c+e+f) ranges from 30% to 80%. - the said cycloaliphatic diamine a) is in the presence of at least one aromatic diamine f) chosen from xylylenediamines, - the said diamine a) represents from 50 mol% to 99 mol% of the total number of moles of diamines a) + f) and - the molar percentage of (a+f)/(a+c+e+f) ranges from 30% to 80%.