New mechanisms of failure of the polymer matrix

Conclusions

• 1. The fracture surfaces of polybutyleneterephthalate were examined in detail in a wide temperature and strain rate range and new types of fracture surfaces were specified.

• 2. It was observed that if failure of the crystalline polymers is brittle, the mirrorlike and rough zones form repeatedly at various resolving power levels.

• 3. A new type of fracture surface typical of the crystalline polymers, i.e., the surface with two zones with different roughness, was described. This type of fracture represents an intermediate stage of transition from brittle fracture to fracture with the formation of craters. Two forms of defects were found on the fracture surface.

• 4. The special features of formation of the new type of fracture surface for the crystalline polymers, i.e., craters, and their growth kinetics were examined. The results show that the number of the craters decreases with increasing strain whereas the area occupied by the craters increases.