A craze consists of a dense array of fibrils separated by voids, and there are two distinct mechanisms responsible for
crazing [3-11].
Company tests show the material is highly resistant to surface
crazing caused by food and beverage contact or extensive dishwashing, out-performing competitive resins such as polycarbonate, SAN and straight acrylic.
2), the craze fibrils bear the
crazing stress [[sigma].sub.cr] as the maximum tensile stress, which is equal to the cohesive stress near the crack tip.
They concluded that
crazing is the dominant deformation mechanism for high impact polystyrene (HIPS) blends, regardless of the strain rate, and the difference in capability to initiate crazes is a dominant factor for the significantly different fracture energy of the two HIPS at the highest strain rate.
A review of the literature addressing
crazing in polymers indicates that a number of different models have been proposed to predict craze formation, growth, and subsequent separation in polymers.
The occurrence of
crazing in semicrystalline polymers, particularly in polyethylene, is well documented [1, 2].
There is also evidence of multiple
crazing in PE100 and BMPE, but there are fewer secondary crazes.
The residual mechanical properties of crazed polycarbonate were then correlated to the
crazing stress, relative craze density and strain rate.
The Design of Experiments (DOE) approach was used to build quantitative empirical models of the residual mechanical properties of crazed polycarbonate as functions of relative craze density,
crazing stress, and strain rate.
Crazing in polymers may arise at crack tips owing to high stress concentration, as reviewed by Kramer and Berger [1, 2].
The present study is being conducted to experimentally measure when and to what extent these stress fields will cause
crazing. Results will be used to support the development of models to predict stress-induced
crazing in these structures.
2) SEM (scanning electron microscope) and TEM (transmission electron microscope) observations on the broken surface revealed that shear yield and
crazing occurred in a whitened portion, and
crazing was observed only near the surface of the broken section in a non-whitened portion.