Monomer polymer solution, glass point

At conversion levels near the glass point of the monomer/ polymer solution, the free volume is low enough that the propagation reaction becomes diffusion controlled. In a development analogous to that for kt> the k behavior is written as... 

We will furthermore present data showing the effect of polymerization temperature on limiting conversion. With polymerizations below the glass transition point of the polymer, the monomer-polymer solution reaches its glass transition point at a conversion <100%. At this point reactions involving small molecules, such as propagation, become diffusion controlled. This causes the rate of polymerization to fall to virtually zero in the normal polymerization time scale, i.e. in practice the reaction rate reaches a limiting conversion <100%. 

This sequence of monomer addition and molecular weight determination by GPC was continued until the maximum molecular weight was observed. At this point, stirring was stopped, and the reaction mixture was filtered through a sintered glass funnel to separate the polymer solution from the urea byproduct. The solution was then added dropwise to 1 L of well-stirred methanol, from which a white, rubbery polymer precipitated. After decantation, the polymer was dried at 80 °C in a vacuum oven. Table III lists the yield and elemental analysis. 

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