Particular mechanical properties

The crucial aspect of NEMS fabricated structures is the realisation that one is dealing with mechanical vibrations of much higher frequencies. In the case of MEMS the resonance frequencies of the fabricated structures are in the range of tens to hundreds of kHz. For NEMS the frequencies are well into the RE range (1-100 MHz). Such a high frequency mechanical vibration needs investigation of physical properties (particularly mechanical properties) in a length scale that has not been done previously. 

Taken together, the new NMR methods enable studies of almost any dynamic process in polymers, and promise to contribute significantly to an improved understanding of the relations between chain motions and macroscopic—in particular mechanical—properties of polymer materials. 

Structure formation that takes place in disperse systems is the result of spontaneous thermodynamically favorable processes of particle aggregation that lead to a decrease in free energy of the system. These processes include coagulation of dispersed phase or condensation of substance in the zones of direct particle contact. The development of spacial networks (disperse structures) of different kinds defines the ability of disperse system to be converted into a material with particular mechanical properties. Such system becomes qualitatively different from its initial, unstructured state. 

The two major classes of proteins are the fibrous proteins and the globular proteins. Fibrous proteins are distinguished from globular proteins by their filamentous, elongated form. Most of them play structural roles in animal cells and tissues, holding things together. Fibrous proteins have amino acid sequences that favor a particular kind of secondary structure which, in turn, confer particular mechanical properties on the proteins. 

On the other hand, in different realizations of the P-i-LMWL state equations, concerning the location of the configurative point and the features of its motion on the state diagram, the system may show different morphological (in particular, mechanical) properties. 

Physical properties of common polymers and elastomers are reported in Tables 11.4 and 11.5, while physical quantities commonly used in the previous table to describe polymers characteristics are listed in Table 11.6 with the corresponding ASTM standards. On the other hand, particular mechanical properties are briefly described below. 

With adhesive bonding, a large variety of substrates can be joined, such as glass, ceramics, plastics, fibre-reinforced plastics, metals and wood. Many more substrates and combinations are possible and each can have significantly different properties, in particular mechanical properties and surface conditions. 

Some particular mechanical property measurements carried out by DMA and discussed in this text include ... 

For his first experiments in polycondensation, Carothers utilized aliphatic diacids and diols. The poor mechanical properties of the corresponding condensation polymers prevented further investigations on aliphatic polyesters. However, polyesters acquired a renewed interest when relationships between molecular structure and physical—particularly mechanical—properties were precisely established. 

Fillers are usually sohd additives that are incorporated into the polymer to modify its physical (particularly mechanical) properties. The fillers commonly used for PVC are given in Box 2.1. It has been found that particle size of the filler has a great effect on the strength of the polymer The finer the particles are, the... 

Apart from point defects, there also exist extended, in particnlar, one-dimensional edge, dislocations a failure of a crystal lattice having in one direction a long (even macroscopic) dimension but small sizes in the other directions (one or several intemuclear distances). Such defects play a very important role in the formation of many properties of crystals, in particular, mechanical properties. 

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