A novel flame retardant [9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxideô triphosphazene (DOPO-TPN)] based on phosphaphenanthrene and cyclotriphosphazene was synthesized and used to improve the flame retardancy of poly(ethylene terephthalate) (PET). The structure of DOPO-TPN was characterized by nuclear magnetic resonance, Fourier transform infrared spectroscope (FTIR), and elemental analysis. PET/DOPO-TPN composites with different amount of DOPO-TPN were prepared and the flame retardancy was determined by limiting oxygen index (LOI) and vertical burning test (UL-94). With the incorporation of 5 wt % DOPO-TPN, the composite achieved a LOI value of 34% and UL-94 V-0 rating. The thermal properties of the PET/DOPO-TPN composites were investigated by thermogravimetric analysis. The flame retardant mechanism was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), FTIR, and scanning electron microscopy (SEM). The Py-GC/MS results showed that DOPO based fragments would exist in the gas phase during the pyrolysis of PET/DOPO-TPN composites which demonstrated that DOPO-TPN could act through gas-phase action to exert flame retardant effect. The results of FTIR and SEM demonstrated that DOPO-TPN could promote the formation of compact and intact char residues to inhibit the heat and combustible gas transmission in condensed phase.

The aquatic fern salvinia can retain an air layer on its hairy leaf surface when submerged under water, which is an inspiration for biomimetic applications like drag reduction. In this research, an electrostatic flocking technique is used to produce a hairy surface to mimic the air-trapping performance of the salvinia leaf.Viscose and nylon flocks with different sizes were selected. A volumetric method was established to analyze the air-retaining performance of the flocking samples, Salvinia molesta and lotus leaves as well.Through air volume change analyses, it is found that another factor that can affect the Salvinia molesta air-retaining ability is the curving of the leaf under water. A flocking sample fabricated by a kind of nylon flock is demonstrated to have a comparable air-retaining ability under static conditions as a Salvinia molesta leaf in its flat form.

The combination of gas-phase and condensed-phase action will contribute to high quality flame retardant. A novel 9,10dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DOPO-DOPC), which contains carbon source was synthesized in favor of conducting the effect of gas-phase as well as promoting the char formation in condensed-phase. The chemical structure of DOPO-DOPC was characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). DOPO-DOPC was used as an additive in poly(ethylene terephthalate) (PET) and epoxy resin (EP). The flame retardancy of PET/DOPO-DOPC and EP/DOPO-DOPC composites were studied by limiting oxygen index (LOI) and UL-94 test. The results showed that the incorporation of DOPO-DOPC into PET or EP could obviously improve their flame retardancy. The LOI values of modified PET or EP, which contained 10 wt % DOPO-DOPC reached 42.8 and 31.7%, respectively. The thermogravimetric analysis (TGA) results revealed that DOPO-DOPC enhanced the formation of char residues. The Laser Raman spectroscopy (LRS) was used to investigate the carbon structure of thermal oxidation residues. Because of the combination of the gas phase flame retardant effect of DOPO moiety and the promoting formation of char residues in condensed phase, the PET and EP composites exhibited significant improvement toward flame retardancy.

Structural changes in mercerized cotton by liquid ammonia (LA) treatment were investigated and correlated with changes in dyeability of cotton fabrics with reactive dyes. The pore structures of mercerized cotton and mercerized-liquid ammonia (M-LA) treated cotton were characterized by inverse size exclusion chromatography (ISEC). Results showed that when the mercerized cotton was subjected to LA treatment, cumulative accessible volume of smaller pores (e.g., 25.2 Å) increased, whereas that of the larger pores (e.g., 56.7 Å) decreased. These results might be related to the changes in the amorphous region of cotton fiber. The decrease in crystallinity of cotton fiber would increase accessible volume of smaller pores. The larger pores might be compressed by extrusion during swelling of microfibrils or elementary fibrils in water. The change in dyeability of fabrics with reactive dyes of various molecular weights could be rationalized using the observed changes in pore structure. Results also showed that ISEC was more suitable than the method employing Chrastil's diffusion equation for analyzing the pore structure of cotton fiber.

No abstract