Chemistry Reference
In-Depth Information
NCO% or OH
number
Functionality
Composition, wt%
Component A
Polyisocyanate
11.7
3
100
Component B
Polyol 1
35
2
83.2
Polyol 2
107.5
2
10.8
Polyol 3
290
3
6.0
(a) Determine the equivalent weights and molecular weights of all the
reactants;
(b) For 1 kg of component A used in the formulation, calculate the
amount of component B needed if a 1.2 molar ratio of NCO to OH is
used;
(c) Calculate f
avg
of the formulation;
(d) Would you expect gelation to occur?
(e) If the amount of polyol 3 used in component B is increased while the
amount of polyol 1 is reduced, what do you expect the mechanical
properties of the resultant coating to be (the molar ratio of NCO/OH
is maintained at 1.2)?
References
[1] W.H. Carothers, J. Am. Chem. Soc. 51 (1929) 2548.
[2] P.J. Flory, Principles of Polymer Chemistry, Cornell University Press, Ithaca, NY,
1953.
[3] R.W. Lenz, Organic Chemistry of Synthetic High Polymers, Wiley (Interscience),
New York, 1967.
[4] P.W. Morgan, S.L. Kwolek, J. Polym. Sci. Part A 2 (1964) 181.
