In situ deformation test

Figure 3. Electron microscopic techniques used to study micromechanical processes in polymers (a) investigation of fracture surfaces by SEM (b) investigation by TEM of ultrathin sections prepared from deformed and selectively stained bulk material and (c) deformation of samples of different thicknesses (bulk, semithin, and ultrathin)9 using special tensile stages with SEM, HVEM, and TEM. The technique in (c) shows the possibility of conducting in situ deformation tests in the electron microscope.

Figure 14. Deformation of toughened PP, showing an increasing number of cavi-tated particles with increasing elongation (SEM image produced in an in situ deformation test). The deformation direction is horizontal.

Some aspects of the first stage of deformation are visible in the in situ deformation test of a PE blend by sfm in Figures 16 and 17 and are also revealed by tern studies of crack-tip crazes in PE (48). 

Figure 4.13 HDPE/VLDPE (80/20) blend in an AFM in situ deformation test. Left before deformation middle and right after average deformation of 16% and 56%, respectively arrows with letters a, b, c, and d mark areas of different elongation at and between soft VLDPE particles (bright) [13]...

SBR filled with 50 phr carbon black, in situ deformation test ... 

Figure 5.9 Sequence of micrographs from an in situ deformation test of HIPS crack propagation in crazes and crack stop at rubber particles crack starts from above deformed SDS in HEM...

The development of such a craze-like deformation band is shown in Fig. 6.3 in SEM in a sequence from an in situ deformation test of HDPE filled with 28 wt.% of about 1 pm AI2O3 particles [9]. The starting step is phase separation and void formation at the larger filler particles and agglomerates (a). Thin matrix strands between closely connected voids are plastically stretched and transformed into long fibrils (b). With increasing strain, craze-like deformation bands appear in the sample (c). Under an optimum balance of size and volume content of particles, as well as of matrix ductility, a remarkable Increase In toughness of such composites can be realized [9,10]. 

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