Characterization of Crazing Behavior in Polystyrene

Polystyrene 의 Crazing 거동 특성

  • 전대진 (금호타이어 기술연구소) ;
  • 김석호 (금호타이어 기술연구소) ;
  • 김완영 (전북대학교 화학공학과)
  • Published : 2004.06.30


Tensile tests of two types of injection-molded polystyrene(PS) samples have been carried out over a wide range of temperature and strain rates in order to characterize their crazing behaviors. Mechanical properties were affected by the formation of crazes as well as test variables. Below the brittle-ductile transition temperature, the tensile stress and the ultimate elongation increased with the molecular weight, strain rate, and with decreasing temperature while the number and average length of crazes also increase. The crazing stress increased with molecular weight, strain rate, and with decreasing temperature. However, the dependence was small compared to the tensile stress. The gap between crazing stress and tensile stress which represents time fur craze formation and growth increased with molecular weight, strain rate, and with decreasing temperature. Crazing was activated near the ${\beta}$-relaxation temperature; crazing stress abruptly decreased at this temperature. During the tensile test, the craze density changed exponentially with the applied stress. At the initial stage, crazes formed slowly. Once a certain number of craze formed, however, the craze density increased rapidly. Craze nucleation and growth occur simultaneously.


  1. R. P. Kambour, 'A Review of Crazing and Fracture in Thermoplastics', Macromol. Rev., 7, 1(1973).
  2. E. J. Kramer, 'Microscopic and Molecular Fundamentals of Crazing' in 'Advances in polymer Science', H. H. Kausch Ed., VoI.52/53, Springer-Verlage, Berlin (1983)
  3. R. P. Kambour, Crazing. in 'Encyclopedia of Polymer Science and Engineering' J. I. Krischwitz Ed., 2nd Ed., Vol.4, John Wiley & Sons, N. Y. (1985)
  4. E. J. Kramer and L. L. Berger, 'Fundamental Processes of Craze Growth and Fracture. in 'Advances in Polymer Science', H. H. Kausch Ed., VoI.91/92, Springer-Verlage, Berlin (1990)
  5. J. Murry and D. Hull, 'Nucleation and Propagation of Cracks in Polystyrene', Polymer, 10, 451 (1969)
  6. J. Murry and D. Hull, 'Fracture Surface of Polystyrene: Mackerel Pattern', J. Polym. Sci., 8, 583 (1970)
  7. B. D. Lauterwasser and E. J. Kramer, 'Microscopic Mechanisms and Mechanics of Craze Growth and Fracture', Phil. Mag., 39(4), 469 (1979)
  8. J. Hoare and D. Hull, 'The Effect of Temperature on the Deformation and Fracture of Polystyrene', J. Mater. Sci., 10, 1861 (1975)
  9. J. Hoare and D. Hull, 'Craze yielding and Stress-Strain Characteristics of Crazes in Polystyrene', Phil. Mag., 26, 443 (1972)
  10. R. N. Haward. B. M. Murphy, and E. F. T. White, 'Relationship between Compressive Yield and Tensile Behavior in Glassy Thermoplastics', J. Polym. Sci., A-2, 9, 801 (1971)
  11. K. Matsushige, S. V. Radcliff, and E. Baer, 'Relationship Between Compressive Yield and Tensile Behavior in Glassy Thermoplastics', J. Appli. Polym. Sci., 20, 1853 (1976)
  12. B. Wunderlich and D. M. Bodily, 'Dynamic Differential Thermal Analysis of the Glass Transition Interval', J. Polym. Sci., C, 6, 137 (1964)
  13. R. F. Boyer, 'Dependence of Mechanical Properties on Molecular Motion in Polymers', Polym. Eng. Sci., 8(3), 161 (1968)
  14. J. R. Martin, J. F. Johnson, and A. R. Cooper, 'Mechanical Properties of Polymers: The Influence of Molecular Weight and Molecular Weight Distribution', J. Macromol. Sci.-Revs. Macrmol. Chem., C8, 57 (1972)
  15. O. Inhai, 'Delayed Yielding of Epoxy Resin Under Tension, Compression, and Flexure. I. Behavior Under Constant Strain Rate', J. Polym. Sci., 11, 963 (1967)
  16. A. E. Moehlenpah, O. inhai, and A. T. Dibenedetto, 'The Effect of Time and Temperature on the Mechanical Behavior of a 'Plasticized' Epoxy Resin Under Different Loading Modes', J. Appl. Polym. Sci., 13, 1231(1969)
  17. J. E. Fellers and B. F. Kee, 'Crarzing Studies of Polystyrene. I. A. New Phenomenological Observation', J. Appli. Polym. Sci., 18, 2355(1974)
  18. N. Brown and X. Wang, 'Direct Measurements of the Strain on the Boundary of Crazes in Polyethylene. Polymer', 29, 463 (1988)
  19. G. H. Michler, 'Correlation Between Craze Formation and Mechanical Behavior of Amorphous Polymers', J. Mater. Sci., 25, 2321 (1990)