Figure 5 shows the ratio of the rate of diffusion to the rate
of reaction. The ratio decreases throughout the reaction time
in the region before the gel point in which many monomers
that diffuse together diffuse apart before reacting. In the region
after the gel point, the rate of diffusion decreases to zero as the
viscosity of the polymer increases to high values. The rate of
reaction proceeds through the intra-molecular mechanisms of
polymer segments.
Figure 6 shows an example of the concentration profile of one
encounter complex. The trend is similar to the profile of the inter-molecular mechanism except it shows a low but significant rate of
reaction after the gel point. Other encounter complexes decrease
to zero at the same time when the maximum reaction temperature is attained.
Figure 4. Experimental data and simulation results of reaction temperature,
viscosity profile, isocyanate moieties and polyol moieties considering the intra-and inter-molecular movement approach. Circles and squares refer to experimental data of temperature and viscosity respectively. Black, green, blue, and
orange lines refer to the simulation results of temperature, viscosity, isocyanate
moieties, and alcohol moieties respectively.
Figure 5. Ratio of the rate of diffusion to the rate of reaction for inter- and
intra-molecular diffusion. Blue and green lines represent the ratio and viscosity
profile respectively.
Table 4. Kinetic parameters used in the simulation code.
