Spectroscopic dichroism polymer orientation

Ultraviolet dichroism has been applied to polymer orientation studies [11,12]. Quantitative analysis of the amount of conjugated unsaturated structure in rubbers can also be determined from ultraviolet and spectroscopic data. Conjugated systems such as polyenes or aromatics... 

A review of rheo-optical techniques by Sherman et al. (1996) notes that there has been an increase in the use of rheo-optic set-ups both for FT-IR dichroism and for dynamic IR dichroism spectroscopies for polymer melts and polymer blends. Skytt et al. (1996) highlight the use of simultaneous measurement of the transient or steady-state rheological properties and IR dichroism to characterize orientation in polymer melts. However, there is little reference to dual spectroscopic-rheological techniques for reactive polymer systems in the literature. 

Generally, from spectroscopic data such as frequency position, band shape, intensity and dichroism of specific absorption bands conclusions can be derived in terms of the applied mechanical stress and the state of order and orientation of the polymer under investigation. An extremely powerful method for the study of transient phenomena in polyuMr deformation and relaxation is rheo-optics which describes the relation between stress, strain and an optical quantity (for example birefringence, infrared absorption, light scattering. X-ray diffraction) measured simultaneously with stress and strain as a function of time In a given rheo-optical method therefore, a mechanical test is combined with one of these various types of optical measurements. 

Measruement of IR dichroism (i.e., a directionally preferred absorption of optical energy) has been well established as a convenient spectroscopic technique for detecting anisotropy of a sample created by preferential molecular orientations. " The specificity of IR absorption bands to individual submolecular groups makes this technique especially suitable for the detailed study of segmental orientations of polymer chains and their dynamics. Absorption of IR radiation is caused by the interaction of the electric field vector of the incident light with the electric dipole transition moment associated with a... 

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