Preparation of Al(OH)3/Acrylic Copolymer Latex by Emulsion Polymerization

The Al(OH)₃/acrylic copolymer latexes were synthesized through the emulsion polymerization of acrylic monomers, butyl acrylate and 2-ethylhexyl acrylate in the presence of surface-functionalized Al(OH)₃ filler particles. The polymerization was stabilized by polyoxyethylene (50) nonyl phenyl ether (NP-1050, nonionic surfactant) and ammonium (POE) alkyl aryl ether sulfate (EU-S133D, anionic surfactant) to produce stable composite latexes. The improved compatibility of Al(OH)₃ surface with acrylic monomers was achieved by the modification with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS). Transmission electron microscopy showed that nano-sized Al(OH)₃ particles were slightly agglomerated in the copolymer latex. When pristine Al(OH)₃ was used as a filler or γ-MPS-modified Al(OH)₃ particles were added above 30 wt% with respect to monomers, unstable latexes were obtained, which were partially precipitated out on standing for prolonged time. The flame retardation effect was not apparent with the incorporation of Al(OH)₃ in the latexes by 30 wt% as shown by LOI test.     

AN EVA/UNMODIFIED NANO-MAGNESIUM HYDROXIDE/SILICONE RUBBER NANOCOMPOSITE WITH SYNERGISTIC FLAME RETARDANCY

A novel EVA/unmodified nano-magnesium hydroxide(NMH)/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber(CFR).The flammability of the ternary composite was studied by cone calorimeter test(CCT).Synergistic effect on flame retardancy was found between silicone rubber and NMH.EVA/CFR ternary nanocomposite showed the lowest peak heat release rate(PHRR)and mass loss rate (MLR)among the samples of virgin EVA,EVA composites.The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.     

PROMOTION EFFECT OF MELAMINE ON FLAME RETARDANCY OF EPOXY RESINS CONTAINING CAGED BICYCLIC PHOSPHATE

Caged bicyclic phosphate (CBP) and its dimelamine salt (PDS) were synthesized and added to epoxy resins to obtain the flame retarded epoxy resin composites. The flammability of the composites was characterized by the limiting oxygen index (LOI) and cone calorimeter tests. The LOI values of flame retarded composites increase consistently with the increase of flame retardant amounts, and they are almost the same when the loading of CBP is the same as that of PDS,although the phosphorus content of PDS is much lower than that of CBP. The total heat release increases in the order of CBP30/ER ＜ PDS30/ER ＜ PDS15/ER ＜ CBP15/ER, whereas that of specific extinction area is CBP15/ER ＞ CBP30/ER ＞ PDS30/ER ≌ PDS15/ER. PDS exhibits more effective inhibition of oxidation of combustible gases. In the tests of thermogravimetric analyses (TG) and Fourier transform infrared spectroscopy (FT-IR), it is found that the degradation of the composites is influenced greatly by the addition of flame retardants. By scanning electron microscopy (SEM), a thick and tight char-layer is observed for PDS30/ER, resulting from the interaction of nitrogen species with phosphorus species.Therefore, the combination of CBP with melamine in the flame retarded system can improve the flame retardancy greatly.     

Flame Atomic Absorption Spectrometry Determination of Tin In Canned Foods After Extraction With Liquid Chelating Exchanger

Abstract

A combined β-diketo liquid chelating exchanger, LCE (RCOCH₂COCF₃; R = C₉H₁₉), separation followed by flame atomic absorption spectrometry method is described for the determinatoin of tin in canned foods. the optimum conditions for the separation and preconcentration of tin e.g., pH, solvent, exchanger concentration, time, effect of various ions and nature of the extracted species have been discussed. Quantitative extraction (100%) of tin with LCE occurs in cyclohexane medium at pH 5.8, the extracted species being . The results of the determination of tin in five canned food samples were as follows (in mg/kg): orange juice, 97.31 ± 0.71; pineapple juice; 145.85 ± 0.59; tomato juice, 70.54 ± 0.91; chicken soup, 21.30 ± 0.65; Vegetable soup, 65.24 ± 0.93. the reliability of the present method has been tested from the recoveries (98.4-101.7%) of tin after adding various known amounts to pineapple juice and vegetable soup solutions.