The esters of hydroxylated aliphatic carboxylic acid are chosen especially from among:a) the partial or total esters of saturated linear monohydroxylated aliphatic monocarboxylic acids; b) the partial or total esters of unsaturated monohydroxylated aliphatic monocarboxylic acids; c) the partial or total esters of saturated monohydroxylated aliphatic carboxylic polyacids; d) the partial or total es