Chemistry Reference
In-Depth Information
5-11
It
Huggins interaction parameter
depends not only on the temperature but also on the composition of a
binary polymer solution. For solutions of polystyrene in cyclohexane, the
Flory
is generally observed that
the Flory
Huggins interaction parameter is determined to have the following
relation:
90
65
T
1
:
2
χ
5
0
:
2035
0
:
3092
φ
1
0
:
1554
φ
1
where T is the temperature in the unit of K and
φ
is the polymer volume
fraction.
(a) Assuming that volume change of mixing is negligible, what is the
Gibb's free energy change of mixing 1 g of polystyrene with a number
average molecular weight of 10
5
g/mol and 1 mol of cyclohexane (J/
mol) at 400 K? The molar volumes of polystyrene and of cyclohexane
are 9.5
10
4
and 108 cm
3
/mol, respectively. Note that R
8.314 J/
3
5
mol K.
(b) What is the critical Flory
Huggins interaction parameter of the poly-
styrene/cyclohexane system?
(c) Does the polystyrene/cyclohexane system have a UCST or LCST?
(d) Determine the theta temperature (K) at
φ
5
0.1.
5-12 A composite consists of 45% by volume of continuous, aligned carbon
fibers and an epoxy resin. The tensile strength and modulus of the fibers is
3000 Mpa and 200 GPa, respectively, while the corresponding parameters
of the cured epoxy are 70 MPa and 2.5 GPa, respectively. Determine (a)
which component of the composite will fail first when the material is
deformed in the fiber direction, and (b) the failure stress of the composite.
References
[1] G. Scatchard, Chem. Rev. 8 (1931) 321.
[2] J.H. Hildebrand, J.M. Prausnitz, R.L. Scott, Regular and Related Solutions, Van
Nostrand Reinhold, New York, 1970.
[3] P.A. Small, J. Appl. Chem. 3 (1953) 71.
[4] K.L. Hoy, J. Paint Technol. 42 (541) (1970) 76.
[5] S. Krause, J. Macromol. Sci. Macromol. Rev. C7 (1972) 251.
[6] E.A. Grulke, in: J. Brandrup, E. Immergut (Eds.), Polymer Handbook, third ed.,
Wiley, New York, 1989, p. VII/519.
[7] A. Beerbrower, L.A. Kaye, D.A. Pattison, Chem. Eng. (December 18, 1967) 118.
[8] P.J. Flory, J. Chem. Phys. 9 (1941) 66010, 51 (1942)
[9] M.L. Huggins, J. Chem. Phys. 9 (1941) 440; Ann. N.Y. Acad. Sci. 43, 1 (1942)
[10] C.M. Hansen, J. Paint Technol. 39 (1967) 104511.
[11] C.M. Hansen, Ind. Eng. Chem. Prod. Res. Dev. 8 (1969) 2.
[12] P. Choi, T.A. Kavassalis, A. Rudin, IEC Res. 33 (1994) 3154.
