Deformation and Fracture Tests

Bulk sample deformation is followed by the observation of surface changes via SEM, ESEM, AFM, or after replication by TEM. Changes inside the bulk material are studied by preparing semithin or ultrathin sections using an ultramicrotome and investigation by TEM or AFM. 

Deformation of thin films or semithin or ultrathin sections in a tensile device and investigation after deformation or in situ by TEM, HEM, ESEM, or AFM. Changing from Method 1 to Methods 2 and 3 allows larger magnifications and yields more details on the micromechanicai processes and their dependence on the actual morphology. 

Ductile behavior can be studied using a modification of Method 2, a bending experiment see Fig. 1.53. A bent specimen is illustrated in Fig. 1.53(a), and a result of deformed rubber-toughened PVC is shown in a TEM micrograph in Fig. 1.53(b). The sample from the loaded area is a chemically stained thin section prepared by ultramicrotomy, showing fibrillated crazes between the acrylic rubber particles (both stained dark). 

Brittle crack or craze propagation can be studied by TEM, where the crack or craze was stabilized by filling the notch tip with epoxy resin see Fig. 1.54. A small sample was cut from the material in front of the notch tip and was chemically treated for fixation and staining. Using an ultramicrotome, ultrathin sections are produced from the stained region, containing the crazed zone and the area ahead of the craze (such an area near a craze tip in HOPE is shown in Fig. 2.47 in Part 11). 

Hgure 1.53 Bending test of a ductile polymer sample (rubber-toughened PVC)  

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