An additional important factor when evaluating these products
is their biodegradability. It is known that alkyl phenol ethoxylates
are more difficult to degrade than the fatty alcohol ethoxylates.
An interesting feature is that the hydrophobic part of the
fatty alcohol ethoxylate is very easily degraded, while degradation
of the hydrophilic polyester residue is noticeably more difficult,
becoming more difficult with increasing chain length.