Response of Stress and Nanoscopic Strain

In all tests the macroscopic response a (i) to the applied signal (i) is rather simple. The monotonous branches of the saw-tooth function (f) are immediately responded by monotonous branches of 7(f). Thus little phase-shift is observed in these low-frequency load-cycling experiments. 

6 P6HY(20/70/10) load cycling. Mechanical and nanostructure parameters, a Material cycled about low pre-strain, b Material cycled about high pre-strain. Mechanical parameters stiain e and stress a. Nanostructure parameters nanostrain e , lateral nanostrain, /, and scattering power Q 

Compatlbilization increases (Fig. 6.6) the stress a(t) for the material reinforced by PA6, as compared to the uncompatibilized sample (Fig. 6.5). At = 0.06 the stress increases from 62 MPa to about 80 MPa. The plus with respect to the PA12-reinforced blend is readily explained by the more effective compatibilization in PA6. Due to its different molecular structure, i.e. the lower amounts of CH2-groups in the repeat units, the chemical bonds between N-atoms from the PA6 and the anhydride 

The response of the nanoscopic strain e to the macroscopic strain e during plain straining is reported in Fig. 6.9. The nanoscopic strain is smaller than the macroscopic strain (e e). e measures only the deformation of the HDPE semi-crystalline stacks. Humbert et al. [20] have monitored tensile tests of isotropic PE by SAXS. They report relative nanoscopic strains e /e 0.5 for 0 e 0.35. Our measurements on oriented blends (cf. Fig. 6.9) return values that are closer to the identity 

6 HDPE/PA Microfibrillar Composites Under Load-Cycling 

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