Chemistry Reference
In-Depth Information
Figure 2.
Comparison between experimental and modeled Crystaf profiles for ethylene/1-hexene copolymers measured at
several cooling rates.
M
MO
is the molecular weight of the mono-
mer (28 g/mol for ethylene).
Following the assumption that the long-
est ethylene sequence (LES) is the key
factor governing chain crystallizability,
instead of molecular weight as for homo-
polymers, we can rewrite Equation (3) to
(8) substituting
calculated fromEquation (11) into account,
the simulated Crystaf profile of copolymers
can be calculated as:
C
mod
el
ðT
C
Þ
1
¼
ð
W
ð
LES
Þð
X
ð
LES
;
T
C
ÞÞ
Þ
1
. Note that the
parameters A and B for binary copolymers
in Equation (5) are no longer constant as
the equilibrium dissolution temperature is a
function of comonomer content.
Taking the information from the weight
distribution function of LES, W(LES),
r
by
LES
r
¼
1
(16)
Using the same approach, the model
parameters (
) were determined
by minimizing the sum of the squares of
the differences between the simulated and
n
,
k
,
A
, and
B
