How to Calculate Polymer M W
What is Polymer M W?
Polymer molecular weight affects properties: higher MW = stronger, higher Tg, lower solubility; calculated from monomers and chain length.
Formula
Calculate M_w = n × M_monomer - (n-1) × 18 (water loss)
Step-by-Step Guide
- 1Input monomer molar mass and degree of polymerization (n)
- 2Calculate M_w = n × M_monomer - (n-1) × 18 (water loss)
- 3Show distribution effects
Worked Examples
Input
Polyethylene: C₂H₄ unit, n=1000
Result
M_w ≈ 28,000 g/mol (number average MW)
Common Mistakes to Avoid
- ✕Forgetting water loss in condensation polymerization
- ✕Confusing number-average vs. weight-average MW
Frequently Asked Questions
Why is molecular weight distribution important?
Broad distribution: poor flow processing, brittle; narrow: processable, stronger.
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