Answer to Question #69183 in General Chemistry for natasha

Question

Describe the effect known as auto-acceleration in the context of polymerising/curing an acrylic denture base. Discuss possible defects arising from this effect and how the curing cycle (curing temperature programme) can be tailored in order to limit auto-acceleration.

Answer 1

Solution:
Autoacceleration (gel effect) is a dangerous reaction behavior that can occur in free-radical polymerization systems. It is due to the localized increases in viscosity of the polymerizing system that slow termination reactions. The removal of reaction obstacles therefore causes a rapid increase in the overall rate of reaction, leading to possible reaction runaway and altering the characteristics of the polymers produced.
The polymerization of methyl methacrylate, deviates strongly from classical mechanism behavior around 20% conversion; in this region the conversion and molecular mass of the polymer produced increases rapidly. This increase of polymerization is usually accompanied by a large rise in temperature if heat dissipation is not adequate.
Autoacceleration can be reduced by adding a solvent or by introducing an inert polymer into the system. And we need to control the temperature.
Source: https://en.wikipedia.org/wiki/Autoacceleration