Depolarized light intensity

The overall crystallization behavior was studied by depolarized light intensity (DLI) and DSC (15,16,17). We observed a decrease in overall crystallization rate in the PBT-rich blends when the PET percentage... 

A more quantified approach to microscopy involves measuring the depolarized light intensity with a photocell, and plotting this quantity as a function of temperature. This approach is particularly useful in determining the clearing transition when rather broad transitions, quite usual for polymers, are obtained Unless care is taken to ensure a constant field of view and constant sample thickness, this method should be considered to be only semiquantitative as a measure of depolarized light intensity. 

The depolarized light intensity curve, Figure 2, shows a sharp loss in intensity beginning at 57°C. and approaches extinction at 58°C. This in-... 

Depolarized Light Intensity and Photometric Thermal Microscopy... 

The technique of depolarized light intensity (DLI) microscopy was introduced by Magill (80) in 1960. Basic elements of the apparatus were a light source, polarizers, a sample holder, an analyzer, and a suitable recording system. Barrall and Johnson (74) and Miller (75, 76) have described applications of this technique to polymeric samples. Miller (75) prefers to call this technique thermal polarization analysis (TPA). 

Figure 9.26. Schematic diagram of depolarized light intensity apparatus (74). A. unitron MPS microscope B. analyzer sheet C. polarizer sheet D. movable abbe condenser E. tungsten lamp F. movable hot stage G. heater H. program thermocouple 1. sample temperature thermocouple J. sample well K. pin plug terminal attached to microscope stand L. shielded cable to Du Pont module M. photocell N, movable mirror O. ocular P. Du Pont 900 differential thermal analyzer module Q. programmer R. X-Y recorder.

Figure 5. DSC traces (-------), depolarized light intensity ( ), and deformation (-X-)...

Thermal optical analysis (TOA), sometimes known as depolarized light intensity (DLI), measures the intensity of light transmitted through a sample. This method uses circularly polarized light and the transmitted intensity can be directly related to sample crystallinity. ... 

The latter is also called the kinetic crystallinity that can be measured by tracing the crystallization process with dilatometer, depolarized light intensity, dynamic X-ray diffraction and DSC. Polymer crystallization is a volume-contraction process. When the dilatometer is used to measure the change of the sample volume with time evolution at a constant crystallization temperature, one obtains the relative crystallinity as... 

The depolarized light intensity will increase with crystallinity (or mesophase formation) due to the light scattering of polymer crystals (or liquid crystals). This method may be more suitable for the kinetics study of liquid crystallization. 

Fig. 4. Depolarized light intensity curves for end members and selected compositions of the phase diagram in Fig. 2.

Typical results of the quenching experiments, i.e. both overall and depolarized light intensities as well as temperature are reported in Fig. 16.6 as function of... 

In thermal optical analysis (TOA), the conversion of plane-polarized light to ellipti-cally polarized light is measured in semi-crystalline polymers. The intensity of the depolarized light transmitted through a sample is a function of the level of crystallinity. Melting and recrystallization phenomena can be analyzed the technique does not appear to be sensitive to glass transitions [88]. The TOA technique is also referred to as thermal depolarization analysis (TDA) and depolarized light intensity method (DLI). 

Structure development has been followed by numerous experimental techniques, many authors often combining several of them rheological measurements, optical microscopy, optical measurements (birefringence, dichroism, turbidity, depolarized light intensity [DLI]), SALS, SAXS, WAXD, and so on. These techniques have been used ... 

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