- 4 molecules with degree of polymerization 2
- 3 molecules with degree of polymerization 3
- 2 molecules with degree of polymerization 7
Number Average Molecular Weight
Example numbers: 2,2,2,2,3,3,3,7,7
4(2) + 3(3) + 2(7) 8 + 9 + 14 31
-------------------- = ------------ = ---- = 3.444
4 + 3 + 2 9 9
From this it should be obvious that the numbers 2,3, and 7 correspond to
"molecular weights" which are represented by the variable M(i), and the
numbers 4,3 and 2 correspond to "number average counts", which are
represented by the variable N(i).
The symbol i is just an index. For the above data we would have
M(1)=2, N(1)=4 M(2)=3, N(2)=3 M(3)=7, N(3)=2
Weight Average Molecular Weight
Example numbers: 2,2,2,2,3,3,3,7,7
2 2 2
4(2) + 3(3) + 2(7) 16 + 27 + 98 141
---------------------- = ------------ = ----- = 4.548
4(2) + 3(3) + 2(7) 31 31
It should be clear that M(i) and N(i) are the same as for the
Number Average Molecular Weight example.Z Average Molecular Weight
Example numbers: 2,2,2,2,3,3,3,7,7
3 3 3
4(2) + 3(3) + 2(7) 32 + 81 + 686 799
---------------------- = --------------- = --- = 5.666
2 2 2 141 141
4(2) + 3(3) + 2(7)
