Condensation polymerization molar mass distribution

For a free-radical polymerization and a condensation polymerization process, explain why the molar mass distribution of the polymer product will be different depending on whether a mixed-flow or a plug-flow reactor is used. What will be the difference in the distribution of molar mass ... 

In a polymerization process the chain length distribution or molar mass distribution (MMD) is influenced by a large number of factors and conditions the kinetics of the reaction plays a very important role. The calculation of the resulting MMD is thus very complicated. For one of the simplest cases, a step reaction with polycondensation, a first-order approach is given here. As an example we take a hydroxy acid HO-R-COOH, which, upon condensation, forms the chain -[-O-R-CO-]n. 

One of the important properties of any polymeric molecule is its molar mass. Furthermore, since the polymeric material does not consist of molecules of the same length, it is important to know the molar mass distribution. To illustrate the typical calculation of the distribution we choose a linear polymer that might be produced by the condensation of an hydroxy acid to produce a polyester. Suppose that we consider the monomer... 

The disadvantage of the mo.st freqently used condensation reactions ( bad control of average molar mass and molar mass distribution ) can be avoided by use of ring opening metathesis polymerization ( ROMP ) for the precursor monomers. So a very accurate control of the length of the polymer backbone is achievable 2. 

Urea-formaldehyde (UF) adhesive resins as the most important type of amino resins were among the first commercially used adhesive systems and still dominate the production of wood based panels [8]. UF resins are based on the reaction of the two monomers urea and formaldehyde they consist of linear or branched oligomeric and polymeric molecules of various molar masses [9, 10]. The degree of condensation is one of the most important characteristics of condensation resins and determines several of their properties the viscosity at a certain solid content increases [11], and flowability and hence the equal distribution of the resin on the furnish (particles, fibers) and the penetration into the wood surface are hindered [12, 13]. 

---