9860

Molecular Weight Distribution in Equilibrium Step-Growth Polymerizations

Step-growth polymerization is a very important process for producing different types of intermediate, commodity, and specialty polymers. For example, polyamides, polycarbonates, polyesters, and polyurethanes can all be synthesized using step-growth polymerization.
In step-growth polymerization, the functionality of the repeating units has a major role in determining the structure of the polymer. Monomers with two functional groups lead to linear polymers. The main parameters that control length and the distribution of the polymeric chains are the conversion or extent of reaction and the amount of the limiting reactant.
The weight chain length distribution in a linear step-growth polymerization (functionality = 2) can be given by:
,
where is the chain length and is the extent of reaction of the limiting reactants.
At the same time, the number chain length distribution can be calculated with:
.
Using these two equations and, as shown in the snapshots, a high degree of polymerization (determined by chain length) can be achieved only with a very high extent of reaction. At the same time the distribution will become broader as the conversion approaches 1.
Finally, values of the weight and mole average degree of polymerization are calculated.

SNAPSHOTS

  • [Snapshot]
  • [Snapshot]
  • [Snapshot]
  • [Snapshot]

DETAILS

Reference
[1] A. Rudin, The Elements of Polymer Science and Engineering, San Diego: Academic Press, 1999.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.









 
RELATED RESOURCES
Mathematica »
The #1 tool for creating Demonstrations
and anything technical.
Wolfram|Alpha »
Explore anything with the first
computational knowledge engine.
MathWorld »
The web's most extensive
mathematics resource.
Course Assistant Apps »
An app for every course—
right in the palm of your hand.
Wolfram Blog »
Read our views on math,
science, and technology.
Computable Document Format »
The format that makes Demonstrations
(and any information) easy to share and
interact with.
STEM Initiative »
Programs & resources for
educators, schools & students.
Computerbasedmath.org »
Join the initiative for modernizing
math education.
Step-by-step Solutions »
Walk through homework problems one step at a time, with hints to help along the way.
Wolfram Problem Generator »
Unlimited random practice problems and answers with built-in Step-by-step solutions. Practice online or make a printable study sheet.
Wolfram Language »
Knowledge-based programming for everyone.
Powered by Wolfram Mathematica © 2014 Wolfram Demonstrations Project & Contributors  |  Terms of Use  |  Privacy Policy  |  RSS Give us your feedback
Note: To run this Demonstration you need Mathematica 7+ or the free Mathematica Player 7EX
Download or upgrade to Mathematica Player 7EX
I already have Mathematica Player or Mathematica 7+