Phase polymers, strength-morphology

A Strength-Morphology Study of Transparent Two-Phase Polymers... 

The optimum morphology is another property necessary for good impact strengths of two-phase polymer systems. According to a theory that attributes improved impact resistance to the presence of rubbery particles, it is necessary to obtain a solid dispersion made of rubber particles of 1000-2000 nm in diameter within the glassy polymer matrix, as shown in Fig. 3.4 [44]. On the other hand, another theory assumes that the rubbery modifier functions as a continuous lattice-like phase having a honeycomb structure [45-47]. If the... 

This drawback can be at least partially eliminated by blending PLLA with other polymers (26-29). In addition, ABS has been used for blending (30). The blends were prepared laboratory mill equipped with a twin-screw. It turned out that uncompatibilized blends of PLLA and ABS have a morphology with big phase size and a weak interface. The blends exhibit poor mechanical properties with low elongation at break and decreased impact strength. 

Given the morphological complexity of AB diblock and ABA triblock copolymers, it might be expected that the phase behaviour of ABC triblocks would be even more rich, and indeed this has been confirmed by recent experiments from a number of groups. From a practical viewpoint, ABC triblocks can also act as compatibilizers in blends of A and C homopolymers (Auschra and Stadler 1993). In addition to the composition of the copolymer, an important driving force for structure formation in these polymers is the relative strength of incompatibilities between the components, and this has been explored by synthesis of chemically distinct materials. 

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