Micromechanical mechanisms

Two parameters are of particular interest the diameter, D, of modifier particles and the distance, A, between particles (interparticle distance). Until now, the literature has given conflicting accounts of the influence of these parameters on different systems. HIPS and ABS have often served as model systems for producing new materials, but the fact that the morphologies as well as the micromechanical mechanisms of toughness enhancement can be different has not always been considered. 

To study the influence of these structural parameters on the micromechanical mechanisms of toughening, several techniques of electron microscopy were used. Electron microscopic techniques allow investigations not only of detailed morphology but also of the micromechanical processes of deformation and fracture (3, 9-11). 

G.H. Michler, Micromechanical mechanisms of toughness enhancement in nanoslnictured amorphous and semicrystalline polymers, in Mechanical Properties of Polymers Based on Nano-Structure and Morphology, ed. by F.J. Balta Calleja, G.H. Michler (Taylor and Francis, London, 2005), pp. 375-428... 

The mechanical behavior of these linear block copolymers is directly related to the composition and morphology (correlated stress-strain curves are presented in Fig. 3.8 in Part II). By changing the macromolecular architecture and processing conditions in block copolymers, very different morphologies with modified mechanical properties and partly new micromechanical mechanisms can be obtained (see Chapter II.3). 

Figure 2.22 Typical micromechanical mechanisms in p-iPP with the characteristic lamellar morphology after uniaxial tensile deformation at room temperature left orientation of the lamellae...

Henning S, Adhikari R, Michler G H, Balta Calleja F J and Karger-Kocsis J (2004) Micromechanical mechanisms for toughness enhancement in 3-modified polypropylene, Macromol Symp 214 157-171. 

Such tests not only provide us with information about the macroscopic properties of the material but also a deeper understanding of its deformation behavior at the micro- and nanoscopic scales. In situ tools allow the local morphology and the deformation in a material that is subjected to local mechanical stresses to be mapped out. Therefore, these studies open up a very direct way to determine structure-property correlations of polymers and to explain them on the basis of nano- and micromechanical mechanisms in dependence on real morphology [2],... 

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