Principles for Rheo-Optical Characterization

3 TENSILE AND RHEO-OPTICAL PROPERTIES 9.3.1 Principles for Rheo-Optical Characterization 

Mechanical properties in the blends of polyolefin materials and elastomers are of considerable importance for engineering applications (40,41). Various elastomers 

Rheo-optical techniques (46 8) afford information on the strain dependence not only of stress but also of optical quantities associated directly with the structure or molecular morphology. The techniques were developed extensively for crystalline polymers to investigate the molecular deformation mechanism underlying the tensile elongation. In this part, the chain orientation behavior is characterized by infrared dichroism measured simultaneously with tensile deformation at a constant rate of elongation. 

The stress-strain curves of iPP and iPP/EHR blends at room temperature, which is above Tg of all samples, are shown in Fig. 9.23. The tensile behavior of iPP is 

The temperature dependence of tensile behavior is summarized in Table 9.2. In this table, open circles represent ductile behavior without stress whitening, and closed circles brittle behavior with stress whitening. Bold lines in the table denote Tg. The table shows that the ductile-brittle transition in the immiscible blends is independent of temperature, suggesting that the fracture will be associated with the boundary separation at the interface between iPP matrix and EHR domains. However, the EHR51 material plays a role of a plasticizer for iPP because the addition of EHR51 lowers the Tg region. This will be because of the incorporation of the EHR molecules into the amorphous region of iPP. The similar results were obtained in the iPP/EBR blends (50). 

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