Mass loss rate , solid polymer

To clarify the mechanisms of the clay-reinforced carbonaceous char formation, which may be responsible for the reduced mass loss rates, and hence the lower flammability of the polymer matrices, a number of thermo-physical characteristics of the PE/MMT nanocomposites have been measured in comparison with those of the pristine PE (which, by itself is not a char former) in both inert and oxidizing atmospheres. The evolution of the thermal and thermal-oxidative degradation processes in these systems was followed dynamically with the aid of TGA and FTIR methods. Proper attention was paid also to the effect of oxygen on the thermal-oxidative stability of PE nanocomposites in their solid state, in both the absence as well as in the presence of an antioxidant. Several sets of experimentally acquired TGA data have provided a basis for accomplishing thorough model-based kinetic analyses of thermal and thermal-oxidative degradation of both pristine PE and PE/MMT nanocomposites prepared in this work. 

The flammability properties of a solid-phase flame retardant can be the result of the formation of carbon residue with silicate layer present in it. The resulting incomplete combustion is reflected in a lower specific heat of combustion and higher CO yield. The primary parameter responsible for the lower HRR of the nanocomposite is the mass loss rate (MLR) during combustion, as shown in Figure 6.9. The MLR of the nanocomposite is significantly reduced from the values observed for the virgin polymer, and also the smoke production rate (SPR), as shown in Figure 6.10. 

The swelling is a necessary precondition of dissolution. All parts of the polymer molecule must be released from the solid mass before it can escape into solution, i.e. the polymer/solvent mixture must be above the effective Tg. The rate of loss of polymer decreases with increasing molecular weight until it practically comes to a halt. The gel thickness increases over time, expanding the object that... 

When flocculants are used the polymer dosage level has to be calculated. On special applications unique calculations will need to be performed. In three-phase work the mass balance needed to work out centrate rates is more complex. Oil recoveries and losses will need to be assessed. With three mass balances, solids, oil and water, some imbalance is to be expected due to experimental error, and care is needed to ensure that these errors are not allowed to affect the reliability of the result. 

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