Fatigue-Resistant Character

Photochromic reactions are always attended by rearrangement of chemical bonds. During the rearrangement, undesirable side reactions take place to some 

Even if the side reaction quantum yield, Os, is as low as 0.001 and B perfectly converts to A, 63% of the initial concentration of A will decompose after 1000 coloration-decoloration cycles. Thus the quantum yield for conversion to byproducts should be less than 0.0001 to repeat the cycles more than 10,000 times. 

0 x 104 in polystyrene protected with PVA in the presence of single oxygen quenchers 

Another important absorption characteristic is an absorption coefficient. High sensitivity requires high absorption coefficients and high quantum yields. The following diarylperfluorocyclopentenes with various electron-donating or -withdrawing substituents were synthesized to reveal the effect of the substituents on the absorption coefficients (8).5 

The compound 22b has a very large value (704 nm, = 4.3 X 104 M-1 cm-1) in CH3 CN. The molecule has an interesting fluorescence property. Although 22a gives a strong fluorescence, 22b has no fluorescence. Such a fluorescence property change, along with the photochromic reaction, can be potentially used for readout in optical memory.17 

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The fatigue resistance character of the following diarylethene was also examined in LB films.1171... 

Figure 5.2. An apparatus used to measure fatigue resistant character.

The properties of filled materials are eritieally dependent on the interphase between the filler and the matrix polymer. The type of interphase depends on the character of the interaction which may be either a physical force or a chemical reaction. Both types of interaction contribute to the reinforcement of polymeric materials. Formation of chemical bonds in filled materials generates much of their physical properties. An interfacial bond improves interlaminar adhesion, delamination resistance, fatigue resistance, and corrosion resistance. These properties must be considered in the design of filled materials, composites, and in tailoring the properties of the final product. Other consequences of filler reactivity can be explained based on the properties of monodisperse inorganic materials having small particle sizes. The controlled shape, size and functional group distribution of these materials develop a controlled, ordered structure in the material. The filler surface acts as a template for interface formation which allows the reactivity of the filler surface to come into play. Here are examples ... 

The analysis of the processes leading to the degradation of solids and various materials is of interest in many different aspects. These include the analysis of the properties of materials, the nature and character of the stressed state, and the means by which loads are applied. The latter include testing using constant strain rates, creep analysis, measurements of stability with loads applied over extended periods of time, resistance to impact, cyclic fatigue, and many others. Numerous standard test methods were developed for various materials under different conditions. The influence of the specific conditions, such as temperature, humidity, and the presence of surface-active substances also represents the subject of essential studies. Depending on the particular combination of all these factors, a particular type of material degradation can be observed. 

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