Diffusion Control Integration for High Temperature Thermoset Kinetic Calculations during Mold Cure
Integrating diffusion control into thermoset kinetic calculations prevents overestimating late-stage mold cure rates near vitrification.
Diffusion Control Integration
Meaning
Kinetic modeling techniques incorporate the slowing effects of restricted molecular mobility on chemical reaction rates. The use of diffusion control integration allows for a more accurate prediction of the final stages of a resin cure. Traditional models often overestimate the speed of the reaction as the material turns solid.
Molecular Mobility
Reactants must move through the resin to find one another and bond. During diffusion control integration the model calculates how the increasing density of the polymer network blocks this movement. This blockage becomes the primary limit on the speed of the cure.
Reaction Retardation
Conversion rates drop significantly once the resin enters a glassy state. The math behind diffusion control integration accounts for this drop by modifying the reaction constant based on the free volume of the material. This ensures the simulation matches the reality of the workshop floor.
Glassy Transition
Achieving a full cure is difficult when the material effectively locks itself in place. If the process does not account for diffusion control integration the parts may be pulled from the mold before they are truly finished. This error leads to parts that deform or fail when they are exposed to service temperatures.
The integration provides the data needed to determine the correct length and temperature of the postcure cycle.