Toughness tensile impact

The properties of immiscible polymers blends are strongly dependent on the morphology of the blend, with optimal mechanical properties only being obtained at a critical particle size for the dispersed phase. As the size of the dispersed phase is directly proportional to the interfacial tension between the components of the blend, there is much interest in interfacial tension modification. Copolymers, either preformed or formed in situ, can localize at the interface and effectively modify the interfacial tension of polymer blends. The incorporation of PDMS phases is desirable as a method to improve properties such as impact resistance, toughness, tensile strength, elongation at break, thermal stability and lubrication. 

The flaw spectrum approach may be capable also of correlating failure data obtained under conditions which appear to give different material behavior. For example, tensile, Izod, and dart drop impact tests all give different impact energies or toughness measures. In part, this may be explained by the simple idea that a different fraction of flaws is active in each test. Equal biaxial loading (as in dart drop) and uniaxial tension (as in tensile impact) give rise to different flaw activities thus it is to be expected that the number of crazes produced in each test will be different. 

The following Tables 4.15. 17 summarize values of tensile-impact toughness a,u and notched tensile-impact toughness tN for some materials. It must be regarded that this test method is not widely spread why no large data pool is available. 

Table 4.15 Tensile-impact and notched tensile-impact toughness of thermoplastic films...

Material Tensile-Impact Toughness (hxj [kJ m ] Notched Tensile-Impact Toughness [kJ m ] Test Conditions Ref. 

Table 4.16 Notched tensile-impact toughness of rigid thermoplastics ...

Fig. 4.62 Tensile-impact toughness <2tN of filler reinforced HNBR and EPDM material as a function of the exposure time test speed vh = 3.7 m s specimen thickness B = 2 mm [09Kah].

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