Page 122 - Handbook of Adhesives and Sealants

90 Chapter Two

in contact with a solid substrate, a visibly different structure in the
polymer near the interface—the so-called transcrystalline struc-
ture—is formed. This region has mechanical properties different from
the ordinary bulk structure of the polyethylene from which it came.
Interphase regions on metals are generally complex oxides. The me-
chanical properties of an oxide on a particular metal substrate depend
on the history of that particular piece of metal. Such interphase prop-
erties are determined by the conditions that generated them.
It is clear that interphases, which are quite thin relative to the
joints in which they are present, will not have much effect on small
deformation properties of the joint. However, they can have remark-
able effects on the ultimate properties such as the breaking stress of
the joint. This is particularly important if the interphase regions are
sensitive to various environments, such as temperate and moisture.
It is also highly probable that interphases are not homogeneous in
the sense that their composition, structure and, therefore, properties
vary across their depth. Research needs to be directed at answering
questions such as how to model the joint to include interphase regions,
what are the appropriate properties of the interphase to measure, and
how do you measure these properties.

References

1. DuNuoy, P. and Lecounte, J., Gen. Physiol., 1 (1919) at 521.
2. Wilhelmy, L., Ann. Phys., 119 (1863) at 177.
3. Harkings, W. D. and Brown, R. E., J. Am. Chem. Soc., 41 (1919) at 499; also Hark-
ings, W. D., Physical Chemistry of Surface Films (New York: Reinhold Publishing,
1952).
4. Young, T., Trans. Roy. Soc., 95 (1805) at 65.
5. Fox, H. W. and Zisman, W. A., J. Colloid. Science, 5 (1950) at 514; also Zisman,
W. A., ‘‘Relation of Equilibrium Contact Angle to Liquid and Solid Constitution’’,
Chapter 1 in Contact Angle, Wettability, and Adhesion, R. F. Gould, ed. (Washington,
D.C.: American Chemical Society, 1964).
6. Dupre, A., Theorie Mechanique de la Chaleur (Paris: Gauthier-Villars, 1869) at 369.
7. Ahagon, A. and Gent, A. N., J. Polym. Sci., Polym. Phys. Ed., 13 (1975) at 1285.
8. Lewis, A. F. and Saxon, R., ‘‘Epoxy Resin Adhesives,’’ Chapter 6 in Epoxy Resins
Chemistry and Technology, C. A. May and Y. Tanaka, eds. (New York: Marcel Dek-
ker, 1973).
9. Schneberger, G. L., ‘‘Chemical Aspects of Adhesive Bonding, Part II: Physical Prop-
erties’’, Adhesives Age, March 1970.
10. Pocius, A. V., Chapter 6, Adhesion and Adhesives Technology (New York: Hanser
Publishers, 1997).
11. Yen Lee, Sheng, ‘‘The Use of Fluoroepoxy Compounds as Adhesives to Bond Fluo-
roplastics Without Surface Treatment’’, SAMPE Quarterly, vol. 19, no. 3, 1988.
12. Bikerman, J. J., The Science of Adhesive Joints (New York: Academic Press, 1961).
13. Baier, R. E., et. al., ‘‘Adhesion: Mechanisms That Assist or Impede It’’, Science, vol.
162, December 1968 at 1360–1368.
14. Adam, N. K., The Physics and Chemistry of Surfaces (London: Oxford University
Press, 1941) at 9.
15. Wenzel, R. N., Ind. Eng. Chem., vol. 28, 1936, at 988.
16. Griffith, A. A., Phil. Trans. Roy. Soc. London, Ser. A, 221, 163 (1920).
17. Mylonas, C., in Proc. Seventh Int. Congr. Appl. Mech., London (1948).