Single craze

Investigation of the crack tip of PMMA after a stable crack growth reveals that, at room temperature, a single craze is present. 

In the higher temperature range, where a single craze develops at the crack tip, it has been shown [46] that a breaking time r of the craze fibrils under a stress, ac> can be defined from the craze length S and the crack-craze velocity vc by ... 

Shearing Shearing + crazing A Multiple eraring x Single craze... 

From the present results, and as long as the crack propagates by a single craze, the calculations indicate that thermal blunting alone cannot be invoked as the explanation of the brittle-to-ductile transition observed at high load-... 

The deformation mechanism in S/DPE is the same as in polystyrene, namely by crazing [11,12]. Figure 25.9 shows an SEM picture of such a single craze on... 

At present there is only very little and indirect information available on the crazing behavior at the tips of fast running cracks in glassy thermoplastics (e.g. s.se.wi) Hence this Section will confine itself to a discussion of the behavior of single crazes at the tips of stationary or slowly moving cracks. 

Differences in the growth behavior between surface crazes and the single craze at a crack tip have been reported. 

The transition from a smooth fracture surface (a single craze has been broken in its midrib) to a rough surface (multiple crazing has occured at the crack tip) has been encountered in many polymers, only the temperature at which the transition occurs... 

A single craze is produced at a running crack-tip in PMMA at 20 °C (or perhaps at any temperature from —25 to 70 °C), at a l.Opm/s velocity, under static loading. The craze is kept stretched and cooled to —25 °C to freeze-in any subsequent relaxation. The load-thickness curve of that craze is measured at 11 Hz. 

Analysis of the fracture toughness of PMMA and of the shape of a single craze at a... 

During the DCG process, a single craze forms the crack tip plastic zone (CTPZ). The craze progressively weakens during each successive load cycle, while the... 

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