Polycarbonate/Sulfonamide Composites with Ultralow Contents of Halogen-Free Flame Retardant and Desirable Compatibility.

A novel halogen-free flame retardant containing sulfonamide, 1,3,5,7-tetrakis (phenyl-4-sulfonamide) adamantane (FRSN) was synthesized and used for improving the flame retardancy of largely used polycarbonate (PC). The flame-retardant properties of the composites with incorporation of varied amounts of FRSN were analyzed by techniques including limited oxygen index, UL 94 vertical burning, and cone calorimeter tests. The new FR system with sulfur and nitrogen elements showed effective improvements in PC's flame retardancy: the LOI value of the modified PC increased significantly, smoke emission suppressed, and UL 94 V-0 achieved. Typically, the composite with only 0.08 wt% of FRSN added (an ultralow content) can increase the limiting oxygen index (LOI) value to 33.7% and classified as UL 94 V-0 rating. Furthermore, the mechanical properties and SEM morphology indicated that the FRSN has very good compatibility with PC matrix, which, in turn, is beneficial to the property enhancement. Finally, the analysis of sample residues after burning tests showed that a high portion of char was formed, contributing to the PC burning protection. This synthesized flame retardant provides a new way of improving PC's flame retardancy and its mechanical property.

[Synthesis and catalytic-isomerization performance of Al-MCM-41 mesoporous sieves].

Al-MCM-41 mesoporous sieves were synthesized at the ambient temperature by using TEOS as silica source, Al(NO)3 x 9H2O as Al source, and cetyl trimethylammonium bromide as templating agent. The framework and surface structures of the synthesized samples were characterized by XRD, N2-adsorption/desorption isotherms, FTIR and SEM etc. The results showed that the samples were the typical Al-MCM-41 mesoporous sieves with the higher ordered-degree and specific surface area (up to 816 m2 x g(-1)) and the narrower pore diameter distribution. Controlling the highest value of Al/Si with the range of 0.06-0.13, and taking temperature programmed calcination would be beneficial to the formation of the highly ordered Al-MCM-41 mesoporous sieves. The evaluating results showed that the synthesized Al-MCM-41 molecular sieves have a higher catalytic activity for isomerization of endo-tetrahydrodicyclo-pentadiene (endo-TCD) into exo-tetrahydrodicyclo-pentadiene (exo-TCD) and adamantane.

[Study on the measurement of residual stresses around indentations in SiC/Al2O3 nanocomposite using fluorescence].

The residual stresses induced by an indentation were studied in 5% SiC/Al2O3 nanocomposite using fluorescence spectroscopy in this work. It was found that within the indentation and the region of about 10 microm outside the impression, the broadening of the R-lines is obvious, and that the compression shift is a strong function of the distance from the indentation centre. From the observed frequency shifts, the hydrostatic stresses in regions sampled in the indentation, and in the complex stress field surrounding it were measured. The same variation regularity of stresses exists along the diagonal direction and the side vertical bisector direction. The symmetry of the residual stress field around the indentation was also found.