Metal ions deformation, resistance

A widely applied concept in the evaluation of metal ion interaction is that of hardness and softness. In general terms, hard and soft suggest the resistance to deformation in response to electric forces. Thus, hard ions have greater resistance to deformation of the electron cloud and soft ions have lesser resistance to deformation. Quantitative scales for metal ion hardness or softness were developed in the 1960s, starting with the HSAB theory developed by Pearson (see Section 3.3.1). 

The TMA experiments showed that the softening points of the PLA ionomers increased upon incorporation of the metal salt groups. The order of the softening points eorresponded to the increase in Tg values (i.e., the dependence on q/a), observed from DSC. Association of the ionic groups produces a physical network, which suppresses chain mobility, and, thus, deformation required higher temperatures. The greatest resistance to penetration was observed for the PLA ionomers with multivalent metal ions. 

Metals, both pure and alloyed, consist of atoms held together by the delocalized electrons that overcome the mutual repulsion between the ion cores. Many main-group elements and all the transition and inner transition elements are metals. They also include alloys—combinations of metallic elements or metallic and nonmetallic elements (such as in steel, which is an alloy of primarily Fe and C). Some commercial steels, such as many tool steels, contain ceramics. These are the carbides (e.g., FeaC and WgC) that produce the hardening and enhance wear resistance, but also make it more brittle. The delocalized electrons give metals many of their characteristic properties (e.g., good thermal and electrical conductivity). It is because of their bonding that many metals have close packed structures and deform plastically at room temperature. 

---