Abstract
The effect of plasticization on the fatigue crack propagation response in polyamides was examined by conducting fatigue tests on specimens of nylon 66 (N66), nylon 6 (N6) and nylon 612 (N612) which had been equilibrated at various levels of absorbed water. In N66 and N6, crack growth rates decreased as the water content was increased to about 2.5wt%; with increasing moisture content, FCP rates increased and at saturation (8.5 wt% H2O) FCP rates were higher than those observed in the dry polymer. Crackgrowth rates in N612 decreased monotonically as the water content increased to saturation (3.2 wt% in this polyamide). These results were interpreted in terms of the competition between enhanced crack-tip blunting and lowering of the specimen modulus. Crack-tip blunting was believed to dominate fatigue behaviour at low water contents (⩽2.5wt%) and contributed to reduced FCP rates. The higher crack-growth rates observed at higher moisture levels were believed to be caused by reductions in material stiffness.
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References
“Zytel” Design Handbook (E. I. duPont de Nemours and Company, 1972).
N. G. McCrum, B. F. Read and G. Williams, “Anelastic and Dielectric Effects in Polymeric Solids” (John Wiley and Sons, New York, 1967).
R. Puffr and J. Sebenda, in “Macromolecular Chemistry, Prague, 1965”, edited by O. Wichterle and B. Sedlacek (Interscience, New York, 1967) p. 79.
P. E. Bretz, R. W. Hertzberg and J. A. Manson, J. Mater. Sci. 14 (1979) 2482.
P. E. Bretz, R. W. Hertzberg, J. A. Manson and A. Ramirez, in “Water in Polymers”, ACS Symposium Series 127 (1980) Paper 32.
M. I. Kohan, “Nylon Plastics”, (John Wiley and Sons, New York, 1973).
“Handbook of Tables for Applied Engineering Science”, 2nd Edn. (CRC Press, Cleveland, 1976).
G. B. Taylor, J. Amer. Chem. Soc. 69 (1947) 635.
A. Mattiussi, G. B. Gechele and R. Francesconi, J. Polymer. Set 7(A-2) (1969) 411.
W. G. Clark, Jr and S. J. Hudak, Jr, J. Test. Eval. JTEVA 3 (1975) 454.
ASTM Standard E647-78T, Annual Book of ASTM Standards (1979).
P. C. Paris, “Fatigue — A Interdisciplinary Approach” (Syracuse University Press, Syracuse 1964) p. 107.
P. E. Bretz, Ph.D. Dissertation, Lehigh University (1980).
J. A. Manson and R. W. Hertzberg, CRC Rev. Macromol. Sci. 1 (1973) 433.
J. A. Manson, R. W. Hertzberg and P. E. Bretz, submitted to the International Conference on Fracture V, Cannes, France, April 1981.
C. G. Bragaw, Proceedings 6th Plastic Pipe Symposium (AGA Gas Research Institute, Columbus, Ohio, 1978) p. 36.
R. P. Burford and D. R. G. Williams, J. Mater. Sci. 14 (1979) 2872.
Idem, ibid, p. 2881.
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Bretz, P.E., Hertzberg, R.W. & Manson, J.A. Influence of absorbed moisture on fatigue crack propagation behaviour in polyamides. J Mater Sci 16, 2061–2069 (1981). https://doi.org/10.1007/BF00542365
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DOI: https://doi.org/10.1007/BF00542365