Toughening efficiency

The above hypothesis, that the toughening efficiency is enhanced by the formation of local agglomerations, requires intensive theoretical calculations of stress distributions as well as the preparation and characterization of morphologies with a controlled level of dispersion and local agglomeration respectively. 

Mechanical Properties. The mechanical properties of the selected blends studied, including the results of tensile, Izod impact, and falling-weight impact tests, are summarized in Table I. Generally, lower-than-expected toughening efficiency (especially for Izod impact) and data scattering were obtained because it is hard to maintain consistent moisture content of the specimens (especially for blends in which PA is the major component). The presence of the compatibilizer in all the blends resulted in consistent and substantial improvement in properties (Nos. 2, 3, and 4 vs No. 1, and No. 20 vs... 

The rubber addition results, as expected, in the presence of a low temperature rubber loss maximum. The DMA measurements also show, however, that a part of the added rubber phase influences the intensity of both PP relaxation effects. Such an effect might be important for the toughening efficiency of the used type of rubber. 

The difference in loss relaxation area between the amorphous C2C3 rubbers (including Vistalon 5600) and that of the amorphous phases of the semi-crystalline C2C3 rubbers is striking. It might be (one of) the reason(s) for the differences in toughening efficiency between these rubbers. Futhermore, the amorphous phase loss areas of the in-situ... 

Comparison of Reactivity vs. Toughening Efficiency of Various Functional Rubbers. . . 216... 

Toughening Efficiency of Maleated Styrene-Ethylene/Butylene-Styrene (M-SEBS) Block... 

Crucial to the high toughening efficiency of the maleated rubbers is the reaction between the bound anhydride functionality and the amine end groups of polyamide (Scheme 8.3) to form the critical graft copolymer at the interface. The graft copolymer effectively compatibilizes the rubber by reducing the interfacial tension according to the currently... 

Since the anhydride functional (maleated) rubbers have been found by many investigators to be one of the most useful system for polyamide toughening, this system will be discussed in more detail, particularly with respect to the effect of various parameters such as the polyamide end groups, rubber composition, and particle size on the toughening efficiency. 

The differences in the observed impact efficiency were attributed to the differences in the average rubber particle size between these systems. The rather small rubber particle size (0.05 p) obtained in the case PA6/m-SEES blends was considered to be too small to be effective for obtaining high fracture toughness. It was suggested that there may be not only an upper limit, but also a lower limit for the rubber particle size for optimum rubber toughening efficiency [32]. 

Similarly, when a mixture of maleated EPR (0.7% MA) and non-reactive EPR was blended at a total of 20% rubber loading in PA6, a maximum in impact improvement could be achieved only with a high content (>70%) of the maleated EPR in the rubber mixture. Thus the degree to which a reactive (maleated) rubber can be diluted with a non-reactive rubber seems to depend on the maleic anhydride content of the reactive rubber. In each of these cases, both the degree of grafting and the consequent rubber particle size seem to reach the optimiun requirement for the toughening efficiency at a particular ratio of the mixtures of reactive and non-reactive rubbers. 

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