Rheo-optics applications

The absorption bands observed in this region can be assigned to overtones and combinations of characteristic fundamental frequencies. Apart from analytical apphcations, NIR spectroscopy has been demonstrated to be of value also to rheo-optical applications [17, 114, 115], Thus, although NIR spectra are generally less informative than their mid-infrared analogs due to overlap of absorption bands, the details of the changes in crystallinity, conformation, and orientation are also contained in the overtone and combination vibrations [17, 113],... 

Macromotecular Symposia Vol.119, July 1997, p.1-13 APPLICATIONS OF TWO-DIMENSIONAL CORRELATION SPECTROSCOPY IN DEPTHPROFILING PHOTOACOUSTIC SPECTROSCOPY, NEAR-INFRARED DYNAMIC RHEO-OPTICS, AND SPECTROSCOPIC IMAGING MICROSCOPY Noda I Story G M Dowrey A E Reeder R C ... 

Clasen C, Kulicke W-M (2001) Determination of viscoelastic and rheo-optical material functions of water soluble cellulose derivatives. Prog Polym Sci 26 1839-1919 Coffey DG, Bell DA, Henderson A (1995) Food polysaccharides and their application. Marcel Dekker, New York... 

The advent of rapid-scanning FTIR systems has tremendously expanded the application of vibrational spectroscopy in the field of rheo-optics and will certainly stimulate further progress in this research area. A similar developm t can presently be observed for X-ray diffraction since the availability of synchrotron... 

In conclusion, rheo-optical FTIR studies of this class of polymers provide a more detailed insight into their orientation and recovery mechanisms and contribute to a better correlation and optimization of their chemical structure and engineering applications. 

Sections 9.S. 1-9.S.9 briefly discuss applications of rheo-optics that have been selected to illustrate the main points made in the preceding text and to demonstrate the breadth and power of iheo-optical experiments. 

The application of rheo-optics is by no means restricted to polymer solutions and melts. As an example. Figure 9.5.9 shows the birefringence of a dilute colloidal suspension (ferric hydrous oxide)... 

Lodge, T. P. Rheo-Optics Flow Birefringence, Chap. 9 of Macosko, C. W. Rheology Principles, Measurements and Applications. (1994) VCH Publishers, NY, Weinheim... 

In summary, we see that it is not possible to assume that the simple rheo-optical law, equation (8), is universally applicable. It will generally be expected to apply only when the molecular structure of the material is disturbed by a small amount from its equilibrium configuration this will be in shearing flows at low stresses. For strong flows of the elongational type, and especially in dilute solutions, where it is easy to deform the structure greatly, one may expect the simple concept to fail. 

Finally, we mention some other applications of rheo-optics. It has been used to study liquid crystals, has utilized IR spectroscopy, and heat flow birefringence has been observed. Three-dimensional flow birefringence is discussed by Funatsu et al Multicomponent-multiphase materials have been studied. " There has also been considerable theoretical activity. ... 

DIRLD spectroscopy belongs to the characterization techniques known as Vheo-optics. Rheo-optical analysis of materials utilizes electromagnetic probes in conjunction with application of macroscopic mechanical perturbations. It investigates primarily the microscopic or molecular responses of materials under deformation, flow, and relaxation. In dynamic rheo-optical methods, such as dynamic birefringence, light scattering, and X-ray diffraction, relationships... 

Specific applications of DIRLD spectroscopy are presented for several polymer systems to demonstrate the types of information obtainable from this powerful rheo-optical characterization technique. A DIRLD study of atactic polystyrene revealed the existence of highly localized motion of various molecular constituents induced by a macroscopic dynamic strain.It was discovered the rate of reorientational motion of the polystyrene backbone differs considerably from that of the phenyl side groups. The reorientation direction of the phenyl side groups changes dramatically as the temperature of the system is raised above the glass transition temperature. This result may be interpreted as the onset of a new submolecular... 

In Section 2.30.3 of this chapter, attention was focused on the rheo-optical study of polymers at the submolecular and segmental scale. Optical spectroscopy, especially infrared dichroism spectroscopy, was utilized in conjunction with the application of a small-amplitude oscillatory dynamic strain to probe the local dynamics of molecular constituents of polymers undergoing reorientation process. The insights obtained by such measurements were somewhat unexpected, such as the observation that macromolecules exhibit considerable local flexibility and individual rotational freedom with respect to the dynamics of various mesoscopic-scale supramolecular structures. 

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