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The pH-sensitive P(AA-co-NVP)/clay hydrogels were prepared with the monomers of acrylic acid (AA) and N-vinyl-2-pyrrolidone (NVP) based on γ -ray irradiation technique. The influence of pH values of buffer solutions and contents of clay and NVP on the equilibrium swelling ratio (SR) and compressive properties of the hydrogels was investigated in detail. The results of swelling property tests showed that, with the increase of clay content, the SR of hydrogels increases in the same buffer solution, and the SR of hydrogels with different contents of HTMAB-clay is higher than that of P(AA-co-NVP) hydrogels without clay. When the content of clay is 15%, the SR of P(AA-co-NVP)/clay hydrogel is 201 at pH = 9.8, which is 1.23 times of that of the P(AA-co-NVP) hydrogel (164). In addition, the SR of P(AA-co-NVP)/clay hydrogel is higher than that of PAA/clay hydrogel in the same solution. The compressive properties of the hydrogel were also examined. The results showed that the compressive properties of the P(AA-co-NVP)/clay hydrogels were improved distinctly as compared to those of the conventional hydrogels without clay. When the content of clay is 15%, the compression strength of the P(AA-co-NVP)/clay hydrogel is 23 times of that of the P(AA-co-NVP) hydrogel.

Glycolic acid was polymerized under vacuum in the presence and absence of nano sized clay. The added clay catalyzed the condensation polymerization which can be confirmed by recording FTIR spectroscopy and intrinsic viscosity (IV) values. The relative intensity of C=O/CH is increased while increasing the amount of clay. DSC showed the appearance of multiple endotherms of poly(glycolic acid). TGA showed the percentage weight residue remain above 750°C for polymer-nano composite system was 21% and hence proved the flame retardancy (char forming) nature. TEM confirmed the nano size of the clay used to catalyze the condensation reaction. The intrinsic viscosity value was increased with the increase of percentage weight of Hectorite type clay.

The typical immiscible PP/PS blend based clay nanocomposites were prepared via melt blending. The dispersion of clay was determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal stability and dynamic mechanical properties were measured by thermogravimetrical analysis (TGA) and dynamic mechanical analysis (DMA), respectively. Preferential intercalation behavior of clay in PP/PS blends was found. The dispersion of clay is significantly influenced by the polarity of PP and PS, meanwhile the location of clay can be controlled by the alternation of the polarity of PP and PS through chemical modification. The clay migrates from PS phase to PP phase with the improvement of the polarity of PP. However, when the PS is sulfonated, clay migrates back to the dispersed PS phase again. The dispersion and location of clay have profound influence on the thermal and dynamic mechanical behavior of PP/PS blends. The better the dispersion of clay in either continuous phase or disperse phase, the higher the thermal stability of the blends. Besides, samples with clay located in the continuous phase can display the best strengthening effect.

A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene (PP)/organically modified montmorillonite (OMMT) nanocomposites. The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation. The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis (TGA). The structural evolution and composition change in the surface region of PP/OMMT nanocomposites during heating were monitored by means of X-ray photoelectron spectroscopy (XPS), ATR-FTIR and field emission scanning electron microscopy (FESEM). The results showed that the formation of the carbonaceous silicate barrier in the surface region of PP/OMMT nanocomposites resulted from the following three processes: (1) The formation of strong acid sites on the MMT sheets, which could promote the degradation of PP and the carbonization of its degradation products; (2) The gases and gas bubbles formed by decomposition of the surfactant and degradation of PP, which pushed the molten sample to the surface; (3) The degradation of PP and the carbonization of the degradation products, which led to accumulation of MMT sheets tightly linked by the char in the surface region.