Morphology, crazing

Lagaron JM, Capaccio G, Rose LJ, Kip BJ (2000) Craze morphology and molecular orientation in the slow crack growth failure of polyethylene. J Appl Polym Sci 77(2) 283—296... 

Fig. 20. Craze morphology in the diblock copolymer PS/PB 600/256 (from Argon et al. > courtesy of Plastics and Rubber Institute)...

More than thirty years ago Hsiao and Sauer published the first important paper dealing with craze initiation in glassy polymers. In subsequent years several hundred publications have appeared, which were mostly concerned with the phenomenology of crazing (stress and environment effects, craze morphology and kinetics). The first two major reviews on crazing were written ten years ago by Kambour and by Rabinowitz and Beardmore, and they are still serving as a basis of reference. 

To examine craze microstructure, and to study the effect of molecular variables on craze morphology, the method described by Kramer was followed. Samples of polymers were cast in the form of thin films, strained in tension while bonded to carbon-coated grids, and examined in the transmission electron microscope either before or after staining. The TEM observations were made with an Hitachi HU-11 A unit or with a JEOL JEM-IOOCX unit, operating usually at 75-80 kV. Fracture surfaces of many bulk samples were coated with a thin layer of gold-palladium and examined by an Etec scanning electron microscope. 

Figure 10.7 Craze morphology and schematic representation of crazing growth. Reproduced with permission from Ref. [61, 62] (2002,1993), John Wiley and sons.

The following is a brief overview of the subject matter which introduces the reader to the main features of craze morphology and current theories on their initiation, growth, and failure. The reader is pointed in particular to excellent reviews on many aspects of crazing by Rramer (116), Kramer and Berger (117), Kambour (118), and Donald (119,120), and much of the subsequent discussion follows the development in those reviews. 

---