大、中孔发达活性炭的研制

。以大同精选煤为原料 ,并在制造过程中加入适量化学溶液 ,采用斯列普炉炭化、活化 ,可制得大、中孔发达、吸附性能改善的活性炭。     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

Use of polymeric nitrosation reagents for the N‐nitrosation of secondary amines under mild and heterogeneous conditions

A combination of crosslinked poly(4‐vinylpyridinium)chloride [P₄‐H]Cl ( I ) and sodium nitrite or quaternized crosslinked poly(N‐methyl‐4‐vinylpyridinium)nitrite [P₄‐Me]NO₂ ( II ) was used as effective nitrosating agents for the N‐nitrosation of secondary amines under mild and heterogeneous conditions in moderate to excellent yields. The spent polymeric reagents can usually be removed quantitatively and regenerated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1064–1067, 2007     

Modeling the curing kinetics for a modified bismaleimide resin using isothermal DSC

The kinetics of curing for a modified bismaleimide (BMI) resin was investigated to ascertain a suitable cure model for the material. The resin system used in this study was composed of 4,4′‐bismaleimidodiphenylmethane (BMIM) and 0,0′‐diallyl bisphenol A (DABPA, DABA). The BMIM was the base monomer and the DABPA was the modified agent. A series of isothermal DSC runs provided information about the kinetics of cure in the temperature range 170–220°C. Regardless of the different temperatures, the shape of the conversion curves was similar, and this modified BMI resin system underwent an nth‐order cure reaction. Kinetic parameters of this BMI resin system, including the reaction model, activation energy, and frequency factor, were calculated. From the experimental data, it was found that the cure kinetics of this resin system can be characterized by a first‐order kinetic model. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3338–3342, 2004     

Effects of the o‐aromatic ring in the molecular chain on the properties of polyester polyols

A series of liquid polyester polyols from adipic acid (AA), phthalic anhydride (PA), ethylene glycol, propanediol‐1,2, and trihydroxymethylpropane, varying in the molar ratio of PA to AA, were prepared. The effects of the o‐aromatic ring in the molecular chain, which came from PA, on the viscosity, glass‐transition temperature, and thermal degradation temperature of the polyester polyols were studied with viscometry, differential scanning calorimetry, and thermogravimetry. The intrinsic viscosity and glass‐transition temperature increased with the concentration of the o‐aromatic ring increasing. The temperature of the maximum thermal degradation rate for aliphatic polyester polyols was 434.20°C. Two steps of thermal degradation were found when there were o‐aromatic rings in the molecular chain. One thermal degradation temperature was 358.36–360.48°C, and the other was 412.85–427.18°C. Polyester polyols with o‐aromatic rings had higher stability at lower temperatures (<240.00°C). However, aliphatic polyester polyols had higher stability at higher temperatures (300.00–480.00°C). The activation energy and order of degradation were calculated from thermogravimetric curves. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1617–1624, 2002     

Effects of amino acid replacements around the reactive site of chicken ovomucoid domain 3 on the inhibitory activity toward chymotrypsin and trypsin

We have previously shown that replacing the P1-site residue(Ala) of chicken ovomucoid domain 3 (OMCHI3) with a Met or Lysresults in the acquisition of inhibitory activity toward chymotrypsinor trypsin, respectively. However, the inhibitory activitiesthus induced are not strong. In the present study, we introducedadditional amino acid replacements around the reactive siteto try to make the P1-site mutants more effective inhibitorsof chymotrypsin or trypsin. The amino acid replacement AspTyrat the P2' site of OMCHI3(P1Met) resulted in conversion to a35000-fold more effective inhibitor of chymotrypsin with aninhibitor constant (K_i) of 1.17x10^–11 M. The K_i valueof OMCHI3(P1Met, P2'Ala) indicated that the effect on the interactionwith chymotrypsin of removing a negative charge from the P2'site was greater than that of introducing an aromatic ring.Similarly, enhanced inhibition of trypsin was observed whenthe AspTyr replacement was introduced into the P2' site of OMCHI3(P1Lys).Two additional replacements, AspAla at the P4 site and ArgAlaat the P3' site, made the mutant a more effective inhibitorof trypsin with a K_i value of 1.44x10^–9 M. By contrast,ArgAla replacement at the P3' site of OMCHI3(P1Met, P2'Tyr)resulted in a greatly reduced inhibition of chymotrypsin, andAspAla replacement at the P4 site produced only a small changewhen compared with a natural variant of OMCHI3. These resultsclearly indicate that not only the P1-site residue but alsothe characteristics, particularly the electrostatic properties,of the amino acid residues around the reactive site of the proteaseinhibitor determine the strength of its interactions with proteases.Furthermore, amino acids with different characteristics arerequired around the reactive site for strong inhibition of chymotrypsinand trypsin.     

Synthesis and characterization of biodegradable polyethylene by graft copolymerization of starch using glucose–Ce(IV) redox system

Graft copolymerization of low‐density polyethylene (LDPE) onto starch was carried out with glucose–cerium(IV) redox initiator in an aqueous sulfuric acid medium under nitrogen atmosphere. The graft yield was influenced by various parameters like reaction time, temperature, and concentrations of acid, glucose, polyethylene (PE), starch, and initiator. A maximum graft yield of 85.66% was obtained at a temperature of 50°C and at higher concentration of starch. Effect of grafting on crystallinity, morphology, and thermal properties of modified PE has been evaluated using X‐ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA/DTA). Biodegradability of starch‐grafted PE has been tested applying soil‐burial test. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3229–3239, 2006     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006     

Synthesis and Characterization of Segmented Block Copolymers Based on Hydroxyl‐Terminated Liquid Natural Rubber and α,ω‐Diisocyanato Telechelics

Summary: Segmented block copolymers, consisting of non‐polar soft segments from hydroxyl‐terminated liquid natural rubber (HTNR) and polar hard segments from α,ω‐diisocyanato telechelics obtained by “criss‐cross”‐cycloaddition, have been synthesized. The block copolymer formation took place under relatively mild reaction conditions at 80 °C in dichloroethane in the presence of dibutyltin dilaurate as a catalyst. The resulting block copolymers were characterized by spectroscopic techniques (¹H NMR, FTIR, UV‐vis spectroscopy) as well as GPC for molar mass determination. The block copolymers were compression molded in a hot stage press, and the resulting samples were characterized by DSC and stress‐strain measurement. The solubility and phase morphology of the materials have also been studied.

Segmented block copolymer from HTNR and α,ω‐diisocyanato telechelics     

Evaluating the 1931 CIE color‐matching functions

The use of colorimetry within industry has grown extensively in the last few decades. Central to many of today's instruments is the CIE system, established in 1931. Many have questioned the validity of the assumptions made by Wright¹ and Guild,² some suggesting that the 1931 color‐matching functions are not the best representation of the human visual system's cone responses. A computational analysis was performed using metameric data to evaluate the CIE 1931 color‐matching functions as compared to with other responsivity functions. The underlying assumption was that an optimal set of responsivity functions would yield minimal color‐difference error between pairs of visually matched metamers. The difference of average color differences found in the six chosen sets of responsivity functions was small. The CIE 1931 2° color‐matching functions on average yielded the largest color difference, 4.56 ΔE. The best performance came from the CIE 1964 10° color‐matching functions, which yielded an average color difference of 4.02 ΔE. An optimization was then performed to derive a new set of color‐matching functions that were visually matched using metameric pairs of spectral data. If all pairs were to be optimized to globally minimize the average color difference, it is expected that this would produce an optimal set of responsivity functions. The optimum solution was to use a weighted combination of each set of responsivity functions. The optimized set, called the Shaw and Fairchild responsivity functions, was able to reduce the average color difference to 3.92 ΔE. In the final part of this study a computer‐based simulation of the color differences between the sets of responsivity functions was built. This simulation allowed a user to load a spectral radiance or a spectral reflectance data file and display the tristimulus match predicted by each of the seven sets of responsivity functions. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 316–329, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10077