Morphology and characterization of conductive films based on polyaniline‐coated polystyrene latexes

The polyaniline (PANI)‐coated polystyrene (PS) latexes were synthesized, and the electrically conductive films were prepared thereafter. The weight ratio of PANI was 5%. Thermal analysis of the latices was performed using DSC and TGA. In this study, the electrically conductive films were prepared above the PS glass transition temperature (T_g). During the film formation, the effects of the annealing temperature and atmosphere (air or N₂) on the film resistance were investigated. In addition, the film morphology was observed utilizing scanning electron microscopy. The film resistance decreased in the initial heating stage due to the increasing temperature and the compaction of film. Then the film resistance increased with further annealing due to the aging of PANI. Typically, the film resistance was about 6000 Ω/sq, and the conductivity was 0.3 S/cm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5406–5413, 2006     

Detailed Molecular Structure Modeling – A Path Forward to Designing Application Properties of ldPE

Summary: This paper describes a step on the ambitious aim to “design” application properties of ldPE by first simulating the detailed molecular structure of a high‐pressure tubular reactor product. The reactor of a certain configuration produces under well‐defined operating conditions. The next step is to correlate the structure with the application properties. Finally, the sequence will be reversed in order to deduce the operating conditions, which lead to the desired product quality. Two‐dimensional distributions, in molecular weight and branching frequency, as well a two compartment models with a core and a shell stream were simulated and compared with experimental results. Therefore, CFD simulations were carried out to discretize the reaction medium. Samples were taken from both pilot and commercial plants. The TREF‐SEC analytical method was successfully applied in order to measure the microscopic structure of the material. The tremendous numerical problems were solved with the help of the software PREDICI .

Detailed MWD for a pilot scale reactor product.     

Determination of water in cooked cottonseed meats by a modified indirect conductivity method

Summary The modified indirect conductivities and oven-dry moisture percentages were determined on mine Samples of cooked cottonseed meats (1.8 to 13.9% water). Statistical treatment of the data yields the following results: (1) equation of the regression line, {fx177-1} (2) correlation coefficient, 0.998; (3) standard deviation from the regression line, 0.27% water. Ten replicate determinations made on each of two samples containing 2.7 and 7.7% water showed standard deviations of 0.07 and 0.08% water. These results show that the accuracy and precision of the modified indirect conductivity method are satisfactory for practical applications. For a consecutive series of determinations the average time required per determination was about 9 min. This time could be reduced to about 5 min. by using duplicate sets of stirring apparatus. Describes data obtained in research conducted cooperatively by the Cotton Research Committee of Texas and the Texas Engineering Experiment Station.     

Effect of reaction kinetics of polymer electrolyte on the ion‐conductive behavior for poly(oligo oxyethylene methacrylate)–LiTFSI mixtures

The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and ¹H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (T_g), spin–spin relaxation time (T₂), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH₃ showed maximum ionic conductivity, σ_i, two to three times higher in magnitude than that of the σ_i of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003     

High catalytic activity of PdOx/MnO2 for CO oxidation and importance of oxidation state of Mn

PdO_x/MnO₂ has been examined as a catalyst for CO oxidation using a conventional flow reactor at reaction temperatures between 50 and 150°C. In the reaction conditions of GHSV (gashourlyspacevelocity) of 1.22 × 10⁵/h and CO concentration of 2000 ppm, PdO_x/MnO₂ showed higher catalytic activity compared with PdO_x/Mn₂O₃, which had been previously reported as an effective catalyst due to the cooperative action of Pd and Mn₂O₃ for this reaction. The reason for higher activity of PdO_x/MnO₂ than PdO_x/Mn₂O₃ has been investigated using TPR (temperatureprogrammed reduction) and XPS studies. TPR showed that PdO_x/MnO₂ could be reduced by CO at much lower temperature than PdO_x/Mn₂O₃. During the experiment of reduction and oxidation, XPS showed that the valence of Mn in the PdO_x/MnO₂ was between 4+ and 3+, which is higher than that of Mn in the PdO_x/Mn₂O₃ catalyst of which the valence has been reported to be between 3+ and 2+. It is known that in this catalyst system the support supplies oxygen onto Pd, where the oxidation occurs with adsorbed CO, and the ability of the support to provide oxygen improves the performance of the catalyst. Therefore, it was concluded that the readiness of MnO₂ to be reduced with maintaining a higher oxidation state showed higher CO oxidation activity than Mn₂O₃ as support for PdO_x.     

A study of aromatic polyester/chlorinated polymer blends

A large number of studies have been devoted in recent years to the miscibility behavior of linear polyesters with chlorinated polymers, including poly(vinyl chloride) (PVC), chlorinated PVC, chlorinated poly(ethylenes), and copolymers of vinylidene chloride (Saran). However, similar studies with aromatic polyesters are lacking. It is the purpose of this paper to compare the properties of blends made of poly(ethylene terephthalate), poly(butylene terephthalate) or poly(hexamethylene terephthalate) and of various chlorinated polymers. It is shown that a high concentration of chlorine atoms is required to achieve miscibility. Moreover, there is a “miscibility window” in terms of the carbonyl concentration of polyesters, immiscibility being found for carbonyl concentrations outside this window, A similar behavior was observed before for linear polyester/chlorinated polymer blends and for polyester/polycarbonate blends. Solid state small-angle light scattering experiments were also conducted to follow the morphology of the blends as a function of composition. Spherulites were found but their size vary with composition.     

Practical Design Model for Calculating Bubble Diffuser Contactor Ozone Transfer Efficiency

Ozone transfer to water or wastewater is necessary before desirable, effective ozone reactions occur. Several factors affect ozone transfer efficiency, including water quality characteristics, contactor configuration, and applied ozone characteristics. The design model presented in this paper addresses all factors affecting ozone transfer. The model was used to compare measured transfer efficiency with predicted transfer efficiency at four full-scale wastewater ozone disinfection facilities. A relatively good prediction was obtained at each plant.

The paper presents an example calculation of ozone transfer efficiency. Also, the effect of changes to some of the factors affecting transfer efficiency is presented, such as changes in diffuser depth, plant elevation, ozone concentration, water quality (i.e., ozone demand), pH, detention time, temperature, and acombination of factors. The design model may be used to evaluate the effect of changes in plant design on transfer efficiency, but cannot provide an absolute value for transfer efficiency until difficult-to-measure parameters, such as bubble diameter, are known.     

Thermal degradation studies of several pyrrone films

The thermal degradation of several polyimidazopyrrolone (pyrrone) films was studied in air and in vacuum over the range of 100–1000°C. by thermogravimetric analysis (TGA), with the use of both isothermal heating and programmed heating rates of 2, 3, 5, and 7.5°C./min. At pressures of 10^?6 torr or less, maximum weight losses average 30% at 800°C. Rates of volatilization and activation energies were derived to provide comparison between these ladder-type polymers. Mass spectrometric analysis of the pyrolysis gases evolved under vacuum conditions showed that CO, CO₂, and H₂O were the primary volatile products and that they were formed throughout the period of weight loss. Approximate correlation between changes in weight and changes in the total pressure for the vacuum tests indicates that mass spectrometric results could provide quantitative as well as qualitative data. The importance of sample history prior to heating and of sample geometry in developing meaningful and reproducible TGA results is aptly demonstrated. The ability of these materials to absorb readily 5–7 wt.-% of water under ambient conditions and the effect of this property upon weight loss measurements are shown.     

Characteristics of the lipase from the mold,Geotrichum candidum: A review

The moldGeotrichum candidum produces an extracellular lipase, readily concentrated by removal of the culture medium in which the microorganism is grown. The lipase is characterized by a unique, but not absolute, specificity for fatty acids containingcis-9 orcis,cis-9, 12 unsaturation, hydrolyzing both regardless of position within the triglyceride molecule. The enzyme also hydrolyzescis-9-16∶1,cis,trans-9,12-18∶2,trans,cis-9,12-18∶2, palmitoyl oleate and cholesteryl oleate. Digested at comparatively slow rates are:trans,trans-9,12-18∶2, double bond positional isomers of 18∶1 (other thancis-9), stearolic acid, oleoylpalmitate, dilinoleoyl phosphatidyl choline, and saturated acids. The enzyme has an optimum pH of 8.2, and the lyophilized powder is extremely stable, retaining activity for at least eight years when stored at-20 C. A purification of 81-fold has been achieved. One of five papers presented in the Symposium “Microbial Lipolytic Enzymes,” AOCS Spring Meeting, New Orleans, April 1973. Scientific contribution 556, Agricultural Experiment Station, University of Connecticut, Storrs, Conn. 06268.     

High temperature swelling of coal/tetralin mixtures in a high pressure microdilatometer

High pressure microdilatometer experiments were performed on a subbituminous (Wyodak) and a bituminous (Illinois no. 6) coal in helium and hydrogen atmospheres with and without added tetralin. Wyodak coal samples showed no swelling but contractions ranging between 24 and 40 vol% upon heating at 20 and 100 °C min^{− 1} under helium or hydrogen pressures between 150 and 1000 psig (˜1.0–6.9 MPa). Under the same conditions, Illinois no. 6 coals displayed contractions (25–60 vol%) prior to swelling up to 117 vol%. Upon tetralin addition (at 35–190 wt% of the coal), Wyodak coal samples did not swell but showed an increasing contraction with increasing helium or hydrogen pressure due to a slight softening and fusion of the coal particles. In contrast, addition of tetralin at much lower concentrations (5–35 wt%) had a marked effect on the contraction and swelling behaviour of Illinois no. 6. A maximum swelling of 200 vol% was obtained at a tetralin addition of 30 wt%. The increased swelling results from more extensive softening and fusion of coal particles in the presence of tetralin. Both coals showed a decreasing char yield with increasing tetralin concentration. The substantially lower extent of interaction observed between Wyodak coal samples and tetralin compared to Illinois no. 6 coal can be attributed to the differences in pore structure and/or chemical constitution of the two coal samples. Examination of the resultant solids by optical microscopy revealed the microstructural changes produced by thermal treatment in dilatometer experiments.