Nawaz, Mohsan (2005) CHARACTERIZATION OF POLYMERS AND THEIR BLENDS. PhD thesis, Gomal University, D.I. Khan.
The intrinsic viscosity Huggin constant (KH) Laser Light Scattering. UV and IR measurements of nylon 6 are made in its solvent m-cresol and its mixture with different non-solvents like water, 1,4-dioxane, m-cresol and 0.01N HCI. These measurements are also made at different (20-60 oC) temperatures. It has been noted that the intrinsic viscosity. Rg A2 (2)1/2 (calculated from intrinsic viscosity). RH and UV absorbance firstly increase and then decrease with the increase in the decrease with the intensity in IR spectra shows an opposite trend to that of intrinsic viscosity. The dielectric constant calculated from refractive index of mixture of m-cresol, 1,4-dioxane and polymer solutions in it shows a continuous decrease with the amount of 1,4-dioxane. The activation energy obtained through variation in limiting viscosity number with temperature, first decreases and then increases with the addition of 1,4-dioxane. The variation in intrinsic viscosity, Huggins constant and other characteristics of the polymer solutions with solvent composition and temperature are explained in terms of thermodynamic quality of solvent, its selective adsorption, hydrogen bonding and conformational transitions which have taken place due to it. The linear expansion co-efficient is also calculated with the help of cross-over concentration. Cx. The results show that first increases and then decreases by increasing the amount of 1,4-dioxane and decreases with the increase in temperature as observed in case of Rg it has been concluded that firstly the addition of 1,4-dioxane enhances the quality of the solvent, encouraging hydrogen bonding and specific adsorption and then deteriorates which results the conformational transitions in polymer molecules. However in case of HCI the viscosity decreased whereas KH increased linearly with the continents showing continuous deterioration of the quality of solvent In the second phase of the work, investigation are carried out on the compatibility and non-compatibility of various blend systems. The blends studied are nylon-6/PVA/5M H2SO4 PS/PMMA/C6H6, PS/PA/ C6H6, PMMA/PEG/C6H6. These blends are studied with the help of capillary viscometer technique, rotoviscometric technique under different shear rates and dynamic light scattering technique at different temperatures ranging from 20-60 oC. Blends are studied by keeping the concentration of one polymer constant and varying the other. After this study different compositions of the blends are prepared covering a whole range of compositions using the plots of reduced viscosity and poly composition. From all these measurements, it is observed that the various blend systems investigation are not completely compatible and investigations are carried out to check the compatibility and non-compatibility of these blends. The compatibility is determined over the whole range of composition and at temperatures investigated. It is further observed that the result obtained for all these blends through different techniques are consistent with one another. The dynamic light scattering is an advance technique, but still the viscosity is the reliable technique that can be used for the determination of compatibility of the polymers .
|Item Type:||Thesis (PhD)|
|Uncontrolled Keywords:||polymers, intrinsic viscosity, laser light scattering, nylon 6, dielectric constant measurement, solvent system, nonsolvent system|
|Subjects:||Physical Sciences (f) > Chemistry(f2)|
|Deposited By:||Mr. Muhammad Asif|
|Deposited On:||30 Nov 2006|
|Last Modified:||22 Jan 2009 20:45|
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