Monte–Carlo kinetic simulations are performed to study exchange reactions in PET/PEN blends. Chain distribution of the blend is simulated at various mixing conditions. The average length of PET and PEN repeating units decreases with increasing exchange reactions. Derivative of heat flow is modeled at Tg region during mixing. Two peaks are observed on the derivative of heat flow curve at the early stages of mixing, indicating formation of an immiscible blend. With increasing mixing time, miscibility between two phases increasea and the peaks converge toward each other and finally form a single peak. The Monte–Carlo simulation results are in fine agreement with experimental data obtained from different systems. magnified image
The Monte Carlo kinetic simulation method was performed to simulate the entire process of the dispersion polymerization of styrene stabilized by polyvinyl pyrrolidone (PVP) in ethanol. The equilibrium distributions of each component between the continuous phase and the particle phase were calculated by a thermodynamic model. In order to calculate the time course of the concentration of different species in each phase a kinetic model was proposed for the mechanism of dispersion polymerization which took into account the reactions both in the ethanol phase and particles. The role of the stabilizer and aggregation by Brownian diffusion and aggregation by the shear stress of the fluid was quantified for simulating the time course of particle concentration and particle size. The simulation results indicated that aggregation due to Brownian diffusion was the dominant mechanism of aggregation in dispersion polymerization. The effect of monomer concentration was investigated on the particle formation stage by simulating the monomer conversion, particle diameter and particle concentration. Subsequently, the particle growth stage was simulated after sufficient stabilizer was absorbed on the particle surface. The Monte Carlo simulation results for the monomer conversion, particle diameter and particle concentration were in agreement with experimental data.
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