1. 1 Characterizing Molecular Weight Brazel & Rosen Ch. 5 Number average molecular weight: M n

2. 1H NMR 2 http://www.sigmaaldrich.com/materials-science/polymer- science/polymer-analysis.printerview.html

3. Weight average molecular weight: M w DP PDI Perfectly “monodispersed” Monodispersed Polydispersed 3 Living polymerization Free radical polymerization Condensation polymerization Coordination polymerization

4. M n and M w of mixtures 4

5. A polymer mixture is blended with three lots of polyethylene, A, B, C. How much of each lot is needed to make up a load of 50,000 kg with a M w =250,000 and PDI=3.65? LotMwMw PDIMnMn A500,0002.50 B250,0002.00 C125,0002.50 5 Sample problem

6. Methods of MW determination Absolute (M n vs. M w ) – Relative – 6