Continuous solid body structure deformation

Structure formation of polymer CM with low polymer content in the PE-P1 melt apparently takes the following path. Equilibrium phases a and (3 are nucleated during melt crystallization, although do not stratify fully with formation of a single interface because of high viscosity of the pol3uner system. Thus enriched by the polymer, the /3-phase approaches a solid body in its properties and forms a continuous porous matrix with the pol3uner-depleted a-phase. As a result, a gel structure typical of the biphasic polymer with characteristic deformation properties and inclination to syneresis is formed [70]. 

As is well known, classic strength theories are based on the hypotheses of continuity and uniformity of substance distribution in the body being deformed. It is supposed that any arbitrarily small solid particles possess the same properties. However, this does not correspond to reality. The heterogeneity of the structure consists in local distin"-bances of chemical composition, the presence of various impurities, polyciystalline material structure, microcracks, and other defects causing considerable concentration of stresses. This applies equally to adhesive joints of various materials. 

The problem with the semi-solid, self-bodied emulsion systems has been to measure their consistency. Measurements from continuous shear measurements, as they are the result of structural breakdown in the systems under study, have to be treated with some degree of caution. In order to obtain a true measure of consistency or body the systems should be tested in their native state, this requiring a method of measurement which does not disrupt the structures in the emulsion. Thus so-called creep measurements may be applied in which the emulsions are subject to only relatively minor deformities. In creep a shear is quickly imposed on the sample and maintained at a constant level the time-dependent strain or compliance response to this steady stress provides the creep curve. A recovery curve is obtained on removal of the stress, a typical diagram showing the profile for creep and recovery is given in Fig. 8.38. 

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