Crazing environmental

In environmental crazing the specimen fails by the development of a multitude of very fine cracks in the presence of an organic liquid or its vapour. This phenomenon may manifest itself even without the presence of mechanical stress the internal stresses, always present in plastic specimens, can be sufficient. 

Li J, Arnold JC, Isaac DH (1994) Environmental stress cracking behavior of urethane methacrylate based resins - I. Environmental crazing and cracking under bending conditions. J Mater Sci 29(12) 3095—3101... 

We will only consider craze growth and breakdown in air. Environmental crazing has the extra complication of the sorption and diffusion of the environment the reader interested in comparing the mechanisms discussed here with those for environmental crazes are referred to an earlier review paper as well as more recent papers by Brown and others In addition, we will make no attempt to cover all of the older work on craze growth and breakdown in air. Excellent reviews of this work are available This chapter will concentrate on the more recent developments... 

Under dilatational stresses and in contact with solvents, polymers exhibit a cavitational mode of plasticity called environmental crazing. This phenomenon occurs at small strains in the order of a few percent well below the yield point of the polymer. Environmental crazes are normally observed at the surface of a specimen where the penetrating solvent produces a polymer-solvent mixture. Environmental crazing has been extensively discussed in the literature (see e.g. However, one basic problem in studying this phenomenon arises from the fact that the macroscopic state of the sample at craze initiation may differ considerably from the local one which is, in general, poorly defined. 

The influence of solvents has been touched on in Sect. 2.3.2. In fact, the influence of environment on crazing and fracture properties of polymers is of major importance in the practical uses of these materials. There are many ways for the environment to induce fracture by means of stress cracking, stress crazing, chain scission, chain crosslinking, etc. Therefore, environmental fracture has been widely studied, specially from the experimental point of view. Reference is a review of environmental cracking of polymers. Most work on environmental crazing has been done in liquid environments - (solvents and non solvents of the material), or high pressure gas environment, near condensation pressure (liquid nitro-... 

The most promising development of the method for the future will probably be the study of transparent multiphase polymers and environmental crazing, which is a difficult situation where interferometry is one of the rare applicable methods. It should be noted that the field of applicability is already one of the largest of all techniques used to study microscopial aspects of crack tips during propagation. 

Environmental crazing and environmental stress cracking are often the limiting factors in determining how long the properties (and especially the strength) of the polymer will remain sufficient for a plastic part to be useful. These phenomena are dependent upon the solution and diffusion of environmental agents in the polymer [15,16], and thus upon 5. 

Andrews, E. H. and Bevan, L. (1972) Mechanics and mechanism of environmental crazing in a polymeric glass, Polymer, 13, 337-346. 

J. C. Arnold, Environmental Stress Cracking Behavior of Urethane Methacrylate Based Resins. Part I Environmental Crazing and Cracking under Bending Conditions , J. Mater. Sci. 29, 3095-3101 (1994). 

Crazing in the presence of fluids and gases environmental crazing... 

Craze, environmental craze Craze, intrinsic craze Craze-like deformation zones Craze, macro craze Craze, mid-rib Debonding... 

Crazily in the Presence of FInids and Gases Environmental Crazing... 

Figure 13.16 Variation of Jq for PMMA with the solubility parameter of the solvent ( ) pure solvents (o) water isopropanol mixtures. (Reproduced from Andrews, E.H. and Bevan, L. (1972) Mechanics and mechanism of environmental crazing in a polymeric glass. Polymer, 13, 337. Copyright (1972) 1PC Business Press Ltd.)...

Imai, Y. and Brown, N. (1976) Environmental crazing and intrinsic tensile deformation in polymethylmethacrylate. 1. Mechanical behavior. J. Mater. ScL, 11,417. 

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