and
(2.25)
In eqs. 2.24 and 2.25, x is the radial distance around a segment {x = r∕σ), uatt
— uatt∕e is the reduced potential function, and ghc is the average segment-segment
radial distribution function of the hard-chain fluid with temperature dependent seg-
ment diameter, d(T). The analytical evaluation of these integrals is tedious since the
expressions for the average segment-segment radial distribution functions for hard
chain fluid are lengthy. In addition these correlations become less accurate for long
chains and polymers [85]. Thereby these were approximated as a power series of the
packing fraction, with the coefficients being a function of the average chain length of
the mixture.
6
∕ι(τ∕, m) = ∑ai(ni)η', (2.26)
i=0
and
6
h(η,m) = ∑bi (m)ηl. (2.27)
i=0
The coefficients are given by
, . (m — 1) (m — 1) (m — 2)
αi(m) = a0i H--=---au 4---------α2O (2.28)
m mm
and
(2.29)
m mm
46