There is provided composition comprising i) a thermoplastic polymer ii) a compound
having the formula
##STR1##
wherein R1, R2 and R3 are independently
selected from an acyl group or a hydrogen atom, wherein at least one of R1,
R2 and R3 is an acyl group (a short acyl group) having from
2 to 6 carbon atoms, wherein at least one of R1, R2 and R3
is a branched chain acyl group (a long acyl group) consisting of a saturated
chain having 10 to 20 carbon atoms and a hydrophilic branch group.