To investigate and better understand the mechanism of coal spontaneous combustion, the distributions, evolution, and oxidation characteristics of functional groups in different coal samples were characterized using in situ Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) experiments. The macroscopic characteristics of coal spontaneous combustion in relation to functional groups were also analyzed using the thermogravimetric/differential scanning calorimetry–FTIR coupling technique. The experimental results indicated that −OH was the most active groups of coal spontaneous combustion. It not only could react with the absorbed oxygen spontaneously but also found to be the main product of the chemisorption. Consequently, −OH was believed to contribute most both for the loss and increase of coal mass during the process of spontaneous combustion. Aliphatic hydrocarbons were the main components to form −C–O–O• and could be further oxidized into CO. However, reactions between aliphatic hydrocarbons and oxygen were nonspontaneous. EPR experiments suggested that the tendency of coal spontaneous combustion acutely depended on the stability and survival time of free radicals. The more the stable and longer survival time of free radicals are, the lower the tendency of coal spontaneous combustion is.

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Nanosilver/poly(2-acrylamido-2-methylpropanesulfonate sodium) (nano-Ag/PAMPS) composites were synthesized by a microwave synthesis method. The mechanism of catalytic reduction of Ag ion by atomic nitrogen (from PAMPS) was explored. The composites were characterized by the ultraviolet-visible spectroscopy, x-ray diffractometry, transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA). The results show that Ag nanoparticles (AgNPs) possessed face-centered cubic structure and they were homogeneously dispersed in PAMPS matrix. XPS analysis reveals the interaction between AgNPs and PAMPS matrix. TGA proves that the thermal stability of the pure PAMPS was higher than that of the nano-Ag/PAMPS composites.

Nanocopper (nano-Cu)/poly(acetoacetoxyethyl methacrylate (AAEM)-styrene (St)) (P(AAEM-St)) composites were synthesized by reducing copper acetate solution in AAEM and St monomer by ultrasonic technique without adding emulsifier. The morphology, structure, thermal stability, and the interaction between Cu nanoparticles (NPs) and P(AAEM-St) matrix of the composites were characterized using ultraviolet-visible spectroscopy, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), respectively. The results show that Cu NPs possessed face-centered cubic structure, and they were homogeneously dispersed in P(AAEM-St) matrix. XPS and FTIR analyses reveal the interaction between Cu NPs and C¼O of the acetoacetoxy in the copolymer of AAEM and St. TGA proves that the thermal stability of the pure P(AAEM-St) is higher than that of the nano-Cu/P(AAEM-St) composites.