How do you determine the end group of a polymer?
Analysis of polymers using end groups Because of the importance of end groups, there have been many analytical techniques developed for the identification of the groups. The three main methods for analyzing the identity of the end group are by NMR, mass spectrometry (MS) or vibrational spectroscopy (IR or Raman).
What is end group of analysis?
End group analysis is the most important absolute method of obtaining number-average molar mass values for polymers of the step-growth polymerization type. It is shown that large differences may arise between the value determined by titration and the actual amino end group content.
What happens at the end of a polymer?
Mechanisms of termination A method of termination that applies to all polymer reactions is the depletion of monomer. With step-growth polymerization, the reaction can be terminated by adding a monofunctional species containing the same functionality as one or more of the types of monomer used in the reaction.
What is meant by end group?
Definition of end group : a group at the end of a chain of a molecule especially : a functional group at the end of the chain of a linear polymer the amino and carboxyl end groups in a polypeptide.
How do end groups of polymers affect viscosity?
Polymer viscosity is affected by a number of factors, such as the salinity, temperature, concentration, molecular weight, and shear rate. The polymer concentration has a direct relationship with the polymer viscosity. The polymer viscosity increases when the polymer concentration increases, as shown in Figure p27.
What is end group analysis in protein?
Determination of both the nature and the number of terminal groups in a macromolecule, e.g. in proteins, the N‐ and C‐terminal amino‐acid residues; in polynucleotides, the 3′‐ and 5′‐terminal nucleotide residues.
How end groups of polymer affects viscosity?
What is termination by disproportionation?
Termination by disproportionation gives two terminated chains. In this case, one terminated chain will have an unsaturated carbon group while the other terminated end is saturated. Termination by chain transfer can be achieved by hydrogen abstraction from an initiator, monomer, polymer or solvent molecule.
What is the MFI of PP?
3.3. 1 Melt Flow Index
| Plastic/Polymer | ASTM Standard Conditions (°C/kg) |
|---|---|
| Polycarbonate (PC) | 300/1.2 |
| Polypropylene (PP) | 230/2.16 |
| Polyphenyl sulfone (PPSU) | 365/5.0, 380/2.16 |
| Polystyrene (PS) | 200/5.0, 230/1.2, 230/3.8, 190/5.0 |
How do polymers affect viscosity?
The larger the polymer, the more drag and also the more intermolecular attraction, and so the higher the viscosity. So, the viscosity increases with the molecular weight, but not necessarily in a linear way.
What is PDI in polymers?
PDI means polydispersity index. In polymer language this usually refers to ratio of weight average molecular weight (Mw) to number average (Mn) sometimes also called as molecular weight distribution. PDI is used to indicate distribution of polymer chain molecular weights in a given polymer.
Why are end groups important in polymer analysis?
If we know the skeletal structure of a polymer (i.e., how many end groups there are per molecule of polymer) and the end groups are in some way distinguishable from other chemical moieties on the polymer, then end group analysis can be a powerful tool to allow us to “count” the number of molecules in a sample and hence solve for M n.
How to quantify the functionality of a polymer?
There has to be some way to quantify the end group functionality in the first place, usually by titration, elemental analysis, or spectroscopy. Other functional groups on the polymer or in the solution can’t interfere with measurement of your target end groups.
Are there other functional groups on a polymer?
Other functional groups on the polymer or in the solution can’t interfere with measurement of your target end groups. The concentration of end groups has to be sufficient to get an accurate measurement (so may not be good for very high molecular weight samples).
What are the requirements for end group analysis?
There are several requirements that must be met in order for end group analysis to be useful: There has to be some way to quantify the end group functionality in the first place, usually by titration, elemental analysis, or spectroscopy.