ABSTRACT:The thermal degradation of poly(vinyl butyral) (PVB)/glass ceramic, PVB/Ag, and PVB/glass ceramic/Ag composites was investigated with thermogravimetric analysis in nitrogen and air. Thermogravimetric data revealed that the compositions of both inorganic materials in air could greatly influence the thermal degradation of PVB. The degradation reactions of PVB/ceramic and PVB/Ag composites began earlier and accelerated rapidly at lower temperatures. The overall degradation period was obviously shortened for the thermal degradation of PVB/Ag in air, whereas a longer time was required for the PVB/ceramic composite than for PVB. Moreover, dual effects of ceramic and Ag on the thermal degradation of PVB were observed for PVB/ceramic/Ag composites. In addition, the catalytic effects of ceramic and Ag on the degradation reaction of PVB in air were verified with a kinetic analysis.

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Opal-based photonic band gap (PBG) crystals with multiple stop bands were prepared utilizing a sol-gel method. The fabricating procedure includes colloidal crystal syntheses, dispersion, sedimentation, coating, and thermal treatments. Each of the steps can affect the PBG properties, such as stop band locations and ranges. Different stop bands of the photonic crystals can be produced by controlling the particle sizes prepared by the colloidal crystal syntheses. A PBG crystal film with a certain stop band was formed using a particular size of the colloidal crystals coated on glass substrates. In this study, two layers of different particle sizes of PBG crystal were fabricated by different deposition conditions to demonstrate the feasibility of producing multiple stop bands. These conditions can affect the stack layers and structural regularity for forming the PBG layers. In addition, the stop band intensity of the PBG layer can be further improved by the step of thermal treatments. Results imply that multiple stop bands can be feasibly designed and produced as multiple PBG layers coating with a certain SiO2 particle size for each layer.