In this article, we reexamine and extend a relationship proposed earlier be
tween entanglement density and chain dimensions in polymer melts. The power
-law equation presented in the earlier work, relating the entanglement mole
cular weight M-e, melt chain density rho, and the packing length p is teste
d with additional polymer species. Now included are additional polydienes a
nd their hydrogenated derivatives, the isotactic forms of polypropylene and
polystyrene, the essentially syndiotactic form of poly(methyl methacrylate
), along with poly(tetrafluoroethylene), poly(vinylmethyl ether), various p
oly(methacrylates), and polymeric sulfur. We find that within experimental
uncertainties, M-e/rho and p are related through an equation (M-e/rho = 218
p(3)) that is insensitive to temperature (25 degrees C less than or equal t
o T less than or equal to 380 degrees C) and which seems to be universal fo
r flexible Gaussian chains in the melt state. (C) 1999 John Wiley & Sons, I
nc.