Mechanical deformation technique

Solid-state amorphization can be induced through a variety of methods including irradiation, chemical reactions, mechanical-deformation techniques, pressure application, etc., as discussed above. As such, a crystalline phase can be driven into a disordered amorphous state as long as the kinetic constraints inhibiting stable phase formation can be maintained. 

In the second case, the mechanical deformation method will not be standard, but suitable samples will be designed to fit the microscope. The in situ deformation of polymers is almost always conducted in the SEM at low magnification and is most often used for fibers and fabrics. Other microdeformation methods are used to prepare thin films for TEM observations, to model fiber structure or to investigate crazing. Since the mechanical deformation technique is... 

Many of the variations developed to make pressure sensors and accelerometers for a wide variety of appHcations have been reviewed (5). These sensors can be made in very large batches using photoHthographic techniques that keep unit manufacturing costs low and ensure part-to-part uniformity. A pressure differential across these thin diaphragms causes mechanical deformation that can be monitored in several ways piezoresistors implanted on the diaphragm are one way changes in electrical capacitance are another. 

The molecular nature of the neuronal receptors is now becoming understood with the advent of molecular biological techniques. The molecular structure of the mechanosensitive channels has been established only recently. In principle mechanosensitive channels must be opened by mechanical deformation of the neural membrane in which they are em-... 

While conductivities of nanocarbons dispersed in polymers fall short of those of metals, a variety of applications can be unlocked by turning an insulating matrix into a conductor, which requires only small volume fractions that can therefore keep the system viscosity at a level compatible with composite processing techniques. Of particular interest are novel functionalities of these conductive matrices that exploit the presence of a conductive network in them, such as structural health monitoring (SHM) based on changes in electrical resistance of the nanocarbon network as it is mechanically deformed [30]. 

In this tribute and memorial to Per-Olov Lowdin we discuss and review the extension of Quantum Mechanics to so-called open dissipative systems via complex deformation techniques of both Hamiltonian and Liouvillian dynamics. The review also covers briefly the emergence of time scales, the definition of the quasibosonic pair entropy as well as the precise quantization relation between the temperature and the phenomenological relaxation time. The issue of microscopic selforganization is approached through the formation of certain units identified as classical Jordan blocks appearing naturally in the generalised dynamical picture. 

The instrumental aspects and applications of stress mass spectrometry (stress MS) to polymeric materials is reviewed critically from the inception of the technique to the present. Stress MS experiments are performed by mechanically deforming polymeric materials directly in the ion source housing of a time-of-flight mass spectrometer and mass analyzing the evolved volatile compounds. This technique has been applied to the study of stress-induced chemical reactions in polymeric materials, i.e., mechanochemistry, and to the characterization of residual volatile compounds in intractable polymer and composite matrices. Several polymeric systems ranging from polystyrene to fiber-epoxy composites have been studied by this technique. The significance of results achieved to date is assessed, and a systematic framework for further studies is developed. 

Crushing. Byrskii et al. (8) used a vibration ball mill to study the volatile compounds released from a series of crushed polymers. They chose this method to intensify the mechanical degradation process and thus to increase the rate of volatile evolution from the polymer. For polymers such as polyethylene (PE) and polytetrafluoroethylene (FIFE), compound evolution rates are low from other methods of mechanical deformation hence, it is difficult to obtain mass spectra. Byl skii et al. used this technique to successfully obtain mass spectra of compounds from PE and PTFE and demonstrated the feasibility of the vibration ball mill for performing kinetic studies of mechanical degradation as a function of the amplitude of the vibration and duration of the grinding. 

For comparison and reference, stress MS studies on different polymers with different forms of mechanical deformation using different mechanical degradation techniques are summarized in Table II. The major portion of the work has been done on relatively simple polymers, PMMA and PS, by loading in tension. Most of the work was performed by scientists at the A. F. Ioffe Physicotechnical Institute of the Russian Academy of Sciences in Leningrad. 

Dynamic mechanical analysis is routinely used to investigate the morphology of polymers, composites and other materials. The technique can be particularly sensitive to low energy transitions which are not readily observed by differential scanning calorimetry. Many of these processes are time-dependent, and by using a range of mechanical deformation frequencies the kinetic nature of these processes can be investigated. 

The techniques used to obtain the untwisted SmC phase structure in low molar mass LCs and SCLCPs are limited to thin layers. In contrast to this, LC elastomers can be macroscopically uniformly oriented by mechanical deformations [230], and this orientation process is not limited to thin samples or suitable dielectric anisotropy of the material. Furthermore, for LC elastomers the oriented structure can be chemically locked in by crosslinking, resulting in the so-called liquid single crystal elastomers [231],... 

The effect of mechanical deformation on a UV-cured urethane-acrylate polymer and on a silicon carbide/ urethane-acrylate model composite was studied by FTIR microspectroscopy. This technique was used for the first time to measure the width of the interfacial zone beyond which the fibre has no influence on the matrix (161). 

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