Homogenization process caused by competition between phase separation and ester-interchange reactions in immiscible polyester blends: A Monte Carlo simulation
Jh. Youk et al., Homogenization process caused by competition between phase separation and ester-interchange reactions in immiscible polyester blends: A Monte Carlo simulation, J POL SC PP, 38(4), 2000, pp. 590-598
The homogenization process caused by competition between phase separation a
nd ester-interchange reactions in immiscible polyester blends was investiga
ted via the Monte Carlo simulation method. Phase separation and ester-inter
change reactions were performed simultaneously with the one-site bond fluct
uation model on a homogeneous blend of immiscible polyesters. Three differe
nt values of the repulsive pair-interaction energy (E-AB) between segments
A and B and two trial ratios of phase separation to ester-interchange react
ions at a given E-AB were introduced to examine the competition between the
m. Phase separation was monitored by the calculation of the collective stru
cture factor, and copolymerization was traced by the calculation of the deg
ree of randomness (DR). In all cases, as the homogenization proceeded, the
maximum intensity of the collective structure factor initially increased, r
eached a maximum, and finally decreased, whereas the peak position where th
e structure factor had a maximum shifted downward in the early stage and th
en remained unchanged after the intensity of the collective structure facto
r reached the maximum. This indicates that during the homogenization proces
s, the domain size did not change significantly after phase-separated struc
tures were developed distinctly. In this simulation, phase-separated struct
ures were traced until the DR was above 0.8. This result indicates that hom
ogenization can be accomplished via homogeneous ester-interchange reactions
over most of the polyester chains because copolyesters resulting from este
r-interchange reactions do not act as an efficient compatibilizer. (C) 2000
John Wiley & Sons, Inc.