Diffrence bitween mono dispers and polydispers system
Answers
Answer:
The biggest difference that comes to mind is melt viscosity. A monodisperse polymer (Dispersity index of 1.1 or less) will have little to no melt viscosity. This can make it very difficult to process. A polydisperse polymer will have more melt viscosity and can be processed through techniques like extrusion.
Answer:
Polymers consist of repeat units (monomers) chemically bonded into long chains. Chain length is often expressed in terms of the molecular weight of the polymer chain, related to the relative molecular mass of the monomers and the number of monomers connected in the chain. Monodisperse polymers are uniform polymers in which all molecules have the same degree of polymerization or relative molecular mass. The polymer has a polydispersity index (PDI, a measure of the broadness of a molecular weight distribution of a polymer) equal to 1. Many biopolymers, especially proteins, are monodisperse.
While, polydisperse polymer is non-uniform and contains polymer chains of unequal length, and so the molecular weight is not a single value - the polymer exists as a distribution of chain lengths and molecular weights. Man-made polymers are always polydisperse. The best controlled synthetic polymers (narrow polymers used for calibrations) have PDI of 1.02 to 1.10. Step polymerization reactions typically yield values of PDI of around 2.0, whereas chain reactions yield PDI values between 1.5 and 20.