Mechanical and Optical Effects

CHAPTER 11 TUNABLE DIFFRACTION GRATINGS BASED ON AZO MATERIALS 

Elastic Diffraction Gratings Recorded Using a Photomask 

In the completely relaxed state, as nonirradiated areas should be isotropic, the result in Fig. 11.11 suggests that irradiated areas could be anisotropic. The probe 

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If a modest number of cross-links between the polymer backbone are introduced, the polymer Hquid crystal takes on elastomeric properties. The useflilness of these materials probably Hes in the coupling of mechanical and optical effects. 

Figure 11.6. Schematic illustration of coupled mechanical and optical effects on azobenzene mesogens in ATE films, the polarized spectra being recorded with the spectrometer s beam polarized parallel solid tines) and perpendicular dashed lines) to the strain direction. Source Zhao et al., 2003. Reprinted with permission.

Bai, S. Zhao, Y. (2001). Azobenzene-Containing Thermoplastic Elastomers Coupling Mechanical and Optical Effects. Macromolecules, 2001, 34, 9032-9038. 

J. Katajisto, M. Linnolahti, and T.A. Pakkanen, Effect of branching of cyclo-olefin copolymers and polycarbonate polymers on mechanical and optical properties Ab initio and molecular simulation study, /. Mol. Struct., 758(2-3) 189-194, 2006. 

For example vibrational spectra and the study of lattice modes, from which information on effective charges may be obtained via a dielectric model, the mechanical and elastic properties of crystals, proton and other NMR which have provided much interesting information on the bonding of metal complexes, and optical effects such as harmonic generation. 

Bai S, Zhao Y. 2001. Azobenzene containing thermoplastic elastomers coupling mechan ical and optical effects. Macromolecules 34(26) 9032 9038. 

Monika, P. Upadhyaya, N. Chand, Vi Kumar, Effect of poly lactic acid on morphological, mechanical, and optical properties of compatibilized polypropylene and high density polyethylene blend. Compos. Interfaces 21, 133-141 (2014)... 

Rothman A, Kalahiikhov S, Svtadlov N, Dariel MP, Frage N (2014) The effect of grain size on the mechanical and optical properties of spark plasma sintering-processed magnesium aluminate spinel MgAl204. hit J Appl Ceram Technol 11 146-153... 

A premium family of fire retardants is based on reactive compounds that are able to enter into the polymer chain during the polymerization process (mainly polyesters, epoxides and polyurethanes), or monomers that contain fire-retardant groups (like bromo-styrene). Due to their relative physical stability (regarding diffusivity to the atmosphere), the advantage over additives is clear. In this case, it is also important to study the effects on mechanical and optical properties and mainly on weather resistance. 

Processing problems that result in poor optical properties include die lines, low cooling rates, melt fracture, and, for coextrusion, interfacial instabilities. Die lines, as discussed previously, are bothersome because they can reduce both mechanical and optical properties. The cooling rate has a significant effect on polymer crystallization. Because crystallinity in polymers generally reduces optical properties, cooling rates are often increased to improve film clarity. Melt fracture will usually have an effect similar to die lines with respect to optical properties. Any occurrence that creates texture on the film surface will reduce film transparency. Similarly, if the texture occurs at the boundary of two layers in a coextruded film, as happens with interfacial instabilities, the same reduction in optical properties will result. 

Solving the perturbation effects on crystals by systematic counting of mechanical, electrical, and optical effects ... 

To summarize this section, we note that the orientational order in nematic elastomers induces a chain anisotropy, which in turn determines the macroscopic shape of the sample. The manipulation of these shape spheroids by temperature and by electrical, mechanical, and optical fields is at the origin of many of the effects... 

Inhomogeneities in a material can be clearly seen from the rheological behaviour. Some negative effects of inhomogeneities include processing problems, such as surface distortion and even melt fracture, as well as a significant deterioration of the mechanical and optical performance of products. 

CALCULATION OF THE MECHANICAL AND OPTICAL PROPERTIES OF POLYETHYLENE INCLUDING ELECTRON CORRELATION EFFECTS... 

AT Dependence of I (Theory) As mentioned, NA is widely used for improving the performance of semicrystalline polymer materials, such as iPP [62,63]. NA accelerates I and generally improves the mechanical and optical properties of polymers. Most commercial NAs are made of crystalline materials [64-69], This section examines the kinetic effect of epitaxy between NA and polymer crystals [53,70-73],... 

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