  A string link S can be closed in a canonical way to produce an ordinary
closed link L. We also consider a twisted closing which produces a knot K. We
give a formula for the Conway polynomial of L as a product of the Conway
polynomial of K times a power series whose coefficients are given as explicit
functions of the Milnor invariants of S. One consequence is a formula for the
first non-vanishing coefficient of the Conway polynomial of L in terms of the
Milnor invariants of L. There is an analogous factorization of the
multivariable Alexander polynomial.
