Advanced Materials Research Vols. 821-822

Abstract: Photoreduction of Hg (II) is of great importance but remains not fully understood especially in the presence of SO₄^2-. In this study, laboratory experiments were conducted to investigate the reduction of Hg (Cl)₂ with various SO₄^2- concentrations under artificial solar radiation. The whole process was tracked by changing Hg (0) concentrations in argon; the rate constants were calculated by trial method and were compared with other experiment. The results show the reaction rate decreased with increasing SO₄^2- concentrations (0-20 mg L^-1) and the cause of inhibitory effect is assumed with two explanations. The concentration of Hg (0) in argon increased firstly and decreased later in each treatment, since the main reactions in rising and dropping period are different. The comparison indicates that reduction rate is influenced by combined factors such as the form of mercury, the quantity of DOM and TSSs, depth of water and quality of light source.

Abstract: Waterborne UV curable polyurethane emulision containing C=C bond was prepared with self-emulsification. 3% water soluble photoinitiator was added to the polyurethane emulision, and polyurethane films was prepared by ultraviolet irradiation. The structure of the polyurethane emulision and films were confirmed by means of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis. FTIR test result shows that cross linking and solidification reaction of C=C double bond happened after UV irradiation. When C=C content increases, the particle size of polyurethane emulision increases, crosslinking degree of films increases, water resistance and heat resistance have both been improved. When C=C content is 8.51%, gel content is more than 90% and the lowest water absorption can be 12.5%.

Abstract: Bisphenol A (BPA) is an important organic intermediate that is an estrogen and an environmental endocrine disrupting chemical. Bisphenol A is used widely in the production of consumer goods, polycarbonate plastics, epoxy resins. A large amount of studies have indicated that BPA might affect human health. In this work, four different tea (Tieguanyin tea, Black tea, Maofeng tea, Jasmine tea) were tested to verify if they were able to increase the BPA release from the PC cup. High performance liquid chromatography (HPLC) with fluorescence detection (FLD) was used to quantify BPA. Result showed that the heating time and temperature could have an influence on BPA migration from polycarbonate plastic. BPA migrated into tea water from polycarbonate plastic, especially when heated to high temperatures. Relatively high levels of BPA were found to be released into food simulants water from high concentration tea water.

Abstract: As a new-type ceramic fiber, boron nitride fiber has excellent performance, such as high thermostability and wave-transparent. Similar to carbon fiber, the preparation of boron nitride fiber mainly employs the conversion method via organic precursor. In this article, some works on the synthesis of organic precursor for boron nitride fiber are summarized. Advantages and disadvantages of these works are also mentioned, and the prospects for research trend of boron nitride fiber are viewed.

Abstract: Poly (butylene succinate) (PBS) was mixed with Poly (lactic acid) (PLA) in the melt state. The PLA/PBS blends with different constitution were produced. The samples were buried in laterite. Samples were dug out of soil after the burial for 10, 20, 30, 40, 50 and 60 days, respectively. The weight loss and molecular weight of the sample were tested. The analysis showed that the nearly exponential decrease in average molecular weight as a function of degradation time. The PLA and PBS have the similar degradation behavior in the soil.

Abstract: Poly (butylene succinate) (PBS) was mixed with Poly (lactic acid) (PLA) through Haake Reomix, a new type of biodegradable materials can be obtained. With the increasing addition of PBS and the raise of the solution basicity, the degradation rate of blends increase sharply. The GPC analysis can approve the reduction of molecular weight in the degradation process of PLA/PBS blends.

Abstract: initiator is one of the most important conditions of synthesizing efficient strength agent CPAM. To begin with initiating mechanism, three redox systems of acrylamide aqueous polymerization (NH₄)₂S₂O₈/ Na₂ SO₃, K₂S₂O₈/NaHSO₃ and K₂S₂O₈/Na₂ S₂O₄ have been studied. The effects of different kinds of initiator, initiator concentration, and monomer concentration as well as polymerization temperature on relative molecular weight and strength effects of CPAM have been investigated. K₂S₂O₈/Na₂ SO₃ is the most useful system in synthesizing efficient strength agents.

Abstract: Four wholly aromatic Poly (amide-sulfonamide) s (PASAs) were synthesized by the solution polycondensation from m-chlorosulfonyl benzoyl chloride and aromatic diamines in tetramethylene sulfone and substituted 2-Piucoline as the acid acceptor. The chemical structures of PASAs were characterized by FTIR, ¹HNMR. Thermal properties of PASAs were investigated by TGA.

Abstract: Polyureas series were synthesized via two-step solution process by reaction of sophorone diisocyanate (IPDI), amine terminated polyether (Jeffamine D-2000) with different chain extenders including dimethyl-thiotoluene diamine (E300), 1,6-hexamethylene diamine (HDA) and 4,4-diamino cyclohexylmethane (H₁₂MDA). The structure of polyureas was characterized and thermal properties were measured by TGA and DSC. The influence of diamine chain extenders on gel time of polyurea was investigated. The gel time was prolonged to 753s using the E-300 as the chain extenders.

Abstract: In this paper, a series of polyimide (PI) films with different monomer mole ratios between PMDA and ODA (0.980: 1, 0.990: 1, 1.000: 1, 1.010: 1 and 1.015: 1) were prepared in order to investigate the effect of molecular weight on optical properties. Inherent viscosity values were taken as a measure of the molecular weight. The fluorescence properties of the PI films have been measured. The fluorescence spectra show that three obvious emission peaks can be observed at 583 nm (1.00 dL/g), 594 nm (1.42 dL/g) and 603 nm (1.57 dL/g) respectively. In addition, emission peaks show red-shift with the increase of molecular weight, which can attribute to the decease of orbital energy caused by conjugated effect.