Demulsification of Solids‐Stabilized Emulsions Under Microwave Radiation

Experimental data are presented to show the influence of solid particles on demulsification. It was found that the solid particles could effectively resist demulsification. Compared with conventional heating, microwave radiation can enhance the demulsification rate by an order of magnitude and increase the demulsification effectiveness. The demulsification effectiveness of the emulsions stabilized by graphite powder can reach 82%–89% in a very short time under microwave radiation, whilst that of the emulsions stabilized by barium sulfate can attain 100% under similar conditions.     

Distinguishing authentic and counterfeit banknotes by surface chemical composition determined using electrospray laser desorption ionization mass spectrometry

Electrospray laser desorption ionization mass spectrometry (ELDI/MS) was used to rapidly distinguish authentic banknotes from counterfeits of the US dollar and the New Taiwan dollar. The banknotes' surfaces were irradiated with a pulsed ultraviolet laser, after which the desorbed ink compounds entered an electrospray plume and formed ions via interactions with charged solvent species. Authentic banknotes were found to differ from their counterfeit equivalents in their surface chemical compositions. The detected chemical compounds included various polymers, plasticizers and inks; these results were comparable with those obtained using solvent extraction followed by electrospray ionization mass spectrometry analysis. Because of the high spatial resolution of the laser beam, ELDI/MS analysis resulted in minimal damage to the banknotes. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and characterization of an active catalyst

As an active catalyst to promote thermolysis of ammonium perchlorate (AP), potassium lead hexanitrocobaltate(II) complex (K₂Pb[Co(NO₂)₆]) was synthesized by the direct deposition method and inverse microemulsion method. Its submicron, size, cube morphology, and crystal structure were investigated by SEM, TEM, and XRD analysis, respectively. Thermal decomposition of K₂Pb[Co(NO₂)₆] was studied by the TG/DSC-IR online system and XRD analysis. The catalyst was decomposed at about 300 °C; its gaseous products were NO₂, NO, and N₂O and its solid products were Pb₃O₄, Co₃O₄, PbO, CoO, and KNO₂. Because thermal decomposition of the catalyst was synchronous with low temperature decomposition of AP, thermolysis of AP was promoted remarkably. In particular, the gaseous products (NO _x ) could directly oxidize the absorbed NH₃. As a result, compared to the data of pure AP, the integral heat of AP added 3.0 wt% of the catalyst multiplied by 280 %, the maximum rate of heat release increased by 634 %. The decomposition of catalyzed AP ended at about 317 °C, at which only less than 30 % of pure AP decomposed.     

Thermal decomposition properties of guanidine nitrate and basic cupric nitrate

Characterized with a large gas production and low combustion temperature, the guanidine nitrate (GN) gas-generating agents are studied and applied widely. The determination factors of thermal decomposition properties of guanidine nitrate and basic cupric nitrate (GN/BCN) gas-generating agents for airbag application was investigated by the thermogravimetry–differential scanning calorimetry–mass spectrmetry–Fourier transform infrared spectroscopy (TG-DSC-MS-FTIR) and automatic calorimeter. Five different mass ratios were concerned. Our study showed that the onset reaction temperatures of GN/BCN mixtures were lower than that of individual GN and BCN. The thermal decomposition of GN/BCN mixtures could be divided into three stages, including the dissociation and escape of crystal water, solid (GN)-solid (BCN) phase reaction, and liquid (GN)-solid (BCN) phase reaction. When mass ratio of GN/BCN was 62.24/37.73, the largest value of the reaction heat was measured to 3152.7 J g^?1, with N₂ and H₂O as the major gases during thermal decomposition.     

Moisture absorption and diffusion in an underfill encapsulant at T > T g and T < T g

Moisture absorption and diffusion behavior of an underfill material used for electronic packaging with a glass transition temperature (T _g) slightly above room temperature have been investigated by the sorption thermogravimetric analysis technique. It has been found that moisture diffusion in this material follows the Fick’s diffusion model, and moisture absorption–desorption is reversible and repeatable. Based on moisture-induced mass gain versus time curve, the diffusion constant can be determined. It was found that below T _g, moisture diffusivity exhibits an Arrhenius temperature dependence, which changes to a different Arrhenius temperature dependence as the temperature increases to T > T _g. The change in diffusivity from T < T _g to T > T _g is accompanied by a significant decrease in the energy barrier for moisture diffusion. Results shed light on the change in moisture diffusion in polymer-based materials in the glassy and the rubbery state.     

Effects of common synergistic agents on intumescent flame retardant polypropylene with a novel charring agent

In this article, the laboratory-made poly (p-ethylene terephthalamide) (PETA) was used as a novel charring agent and it combined with ammonium polyphosphate (APP) to prepare the intumescent flame retardant (IFR). For improving the flame-retardant efficiency of IFRs on polypropylene (PP), several general synergistic agents, such as common zinc oxide (Com-ZnO), nanometer structural zinc oxide (Nano-ZnO), zeolite 4A, and aluminum hypophosphite(Al(H₂PO₂)₃), were added in composites of PP/IFR, and the synergistic effect was investigated by the limited oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TG), thermogravimetry-fourier transform infraredspectroscopy (TG-IR) test, and scanning electron microscopy (SEM). It indicated that the flame retardancy was significantly enhanced in terms of prompting the char formation of PETA and interaction between APP and synergistic agents. Overall, Al(H₂PO₂)₃ was the most effective synergistic agent among them. TG-IR analysis showed that the addition of Al(H₂PO₂)₃ could delay the release of NH₃, and make the release of NH₃ more smooth, which was useful to form a dense char. SEM presented that compact, continuous and good intumescent charring layers were observed in all PP/IFR systems with synergistic agent.