Formation of liquid inclusion induced light scatter in KDP (DKDP) crystals

We describe in this paper the formation of liquid inclusion induced light scatter in potassium dihydrogen phosphate (KDP) crystal and deuterated potassium dihydrogen phosphate (DKDP) crystals. The measurement has been done with an atomic force microscope (AFM). The mechanism of formation of liquid inclusion scatter has been proposed and the effect of super-saturation discussed.     

负载型钯催化剂完全氧化性能的研究

研究了以含有稀土的Ｆｅ－Ｃｒ－Ａｌ合金为载体的铂催化剂的制备及其催化燃烧性能。实验表明：在苯蒸汽浓度为３２４０ｍｇ／ｍ３，空速为３００００／ｈ的催化燃烧实验条件下，经特殊工艺制得的最优催化剂，在９００℃高温下于空气中的烧后，完全燃烧温度为２４０℃，取得了令人满意的结果，同时，提出了催化剂制备的最优方案，并对其催化活性机理进行了初步探讨。     

电合成芳醛生产中的监控分析方法

本工作研究了盐酸羟胺法测定芳醛的适宜条件，测定了本方法的精密度和准确度，结果令人满意。用此方法对电合成芳醛生产中料液及产品中的醛含量进行了分析，测定结果和色谱法、电位滴定法测定一致。     

Gas phase complete catalytic oxidation of aromatic hydrocarbon mixtures

In this work oxidation of benzene and ethenylbenzene (IUPAC name for styrene) as single compounds and in binary mixtures over a Pt honeycomb catalyst were investigated. Both aromatic compounds showed zero-order kinetics over a wide concentration range. The ethenylbenzene reaction rate was affected weakly by the presence of benzene, whereas benzene oxidation was inhibited strongly by ethenylbenzene. The Mars-van Krevelen mechanism (which is generally accepted for single aromatic compound oxidation kinetics) gave rise to inconsistencies in describing mixture behaviour. A different kinetic model is proposed, where benzene reacts from the gas phase and ethenylbenzene is adsorbed on the catalyst competing with oxygen for active sites. This model was able to interpret the oxidation of mixtures quite satisfactorily.     

Synthesis and properties of star-like wholly aromatic polyester fibers

Novel star-like wholly aromatic copolyesters having four arms based on a tetraamine star core, p- and m- hydroxybenzoic acids and 6-hydroxy-2-naphthoic acid have been successfully synthesized and spun into fibers for the investigation of the effect of the star-like structure on improving compressive properties of the fiber. The reactivity of the star core was demonstrated using a model compound with FTIR, ¹H and ¹³C NMR spectroscopy. The ¹³C NMR spectrum of the star-like terpolymer having a molar ratio of 10:1 of the monomers to star core showed a characteristic peak at around δ62 ppm which corresponds to a tetra-substituted carbon and thereby demonstrates that the star core was really incorporated into the polymer. The star-like copolyester exhibited a clear stir opalescence and liquid crystalline morphology in the temperature range of 150-280 °C. However, no transition was observed in the DSC thermogram except a clear T_g at 110 °C. The star-like terpolymer fiber, prepared from a polymer with a molar ratio of 500:1 for the monomers to imide core, was spun in the liquid crystalline state at 180 °C. Fiber structure and properties have been studied.     

Esters from castor oil functionalized with aromatic amines as a potential lubricant

Vegetable oils are very promising alternatives to fossil lubricants due to their abundance, low cost, excellent performance, and environmental friendliness. Due to its multifunctional structure, castor oil is an excellent precursor in the synthesis of new biolubricants. However, it showed poor thermal-oxidative stability and a higher pour point. This study used castor oil fatty acids prepared by transesterification (EHRO), epoxidation (TEPO), and oxirane ring opening with the aromatic amines aniline (ANIL) and p-anisidine (ANIS). The chemical structure of these oils was verified by ¹H and ¹³C NMR analysis, and mass spectrometry. Measurements show that the presence of an aromatic amine increases the viscosity resulting in 172 (ANIL) and 199 (ANIS) cSt at 40°C, but reduces viscosity index to 16 and 1, respectively. In addition, the amine groups can scavenge radicals increasing their thermal and oxidative stability. These products do not oxidize copper, and tribological analysis reveals that ANIS has the lowest torque with wear equivalent to commercial mineral lubricant NH-140.     

Science-guided data analytics for selecting ionic liquid solvents for aromatic extraction

Ionic liquids (ILs) are promising solvents for the aromatic extraction process. An attractive characteristic is the existence of hundreds of ILs that exhibit different properties. To identify key properties of IL solvents for an energy-optimum aromatic extraction, we use process simulation to generate the process datasets for multivariate data analytics with partial least squares, and use science-guided fundamentals to develop an IL heat load variable (HLV). We consider 16 well-studied ILs and correlate process steam duty and process variables affecting equipment size to the HLV for ethylene cracker feeds of low aromatic content. For such feeds in an IL aromatic extraction process, 11 of 16 ILs show energy advantage compared with sulfolane solvent with the lowest energy IL process requiring 57% of total energy required for an equivalent sulfolane process. Our results facilitate the IL solvent selection for pilot tests and subsequent commercialization of an IL aromatic extraction process.     

Flexible Backbone Aromatic Polyimide Adhesives

Continuing research at Langley Research Center on the synthesis and development of new inexpensive flexible aromatic polyimides as adhesives has resulted in a material identified as LARC-F-SO₂ with similarities to polyimidesulfone (PISO₂) and other flexible backbone polyimides recently reported by Progar and St. Clair. Also prepared and evaluated was an endcapped version of PISO₂. These two polymers were compared with LARC-TPI and LARC-STPI, polyimides researched in our laboratory and reported in the literature.

The adhesive evaluation, primarily based on lap shear strength (LSS) tests, involved preparing adhesive tapes, conducting bonding studies and exposing lap shear specimens to 204°C air for up to 1000 hrs and to a 72-hour water boil. LSS tests at RT, 177°C and 204°C were performed before (controls) and after these exposures. The type of adhesive failure as well as the Tg was determined for the fractured specimens.

The results indicate that LARC-TPI provides the highest LSSs, 33 MPa at RT, 30 MPa at 177°C, and 26 MPa at 204°C. LARC-F-SO₂, LARC-TPI and LARC-STPI all retain their strengths after thermal exposure for 1000 hrs and PISO₂ retains greater than 80% of its control strengths.

Most of the four adhesive systems showed reduced strengths for all test temperatures although they still retained a high percentage of their original strength (<60%) except for one case.

The predominant failure mode was cohesive with no significant change in the Tgs.

Although the LARC-F-SO₂ could not be prepared in diglyme alone as the solvent, the properties of the resulting adhesive were notable. The darkening of the adhesive during bonding was typical of systems which utilize amide solvents.     

TOXICOKINETICS OF POLYCYCLIC AROMATIC HYDROCARBONS FROM CONTAMINATED SEDIMENT BY THE AMPHIBIAN LARVAE (PLEURODELES WALTL)

The molecular phototransformation mechanism of nitroarenes, genotoxic and ubiquitous pollutants in the atmosphere, is still under debate. With increasing exposure to radiation 1,6- and 1,8-dinitropyrene (DNP) in acetonitrile showed a decrease in their characteristic absorption bands (396 and 411 nm, respectively) in the presence of O ₂ , N ₂ and H ₂ O, and an increase in the 220–390 nm region and above 450 nm, indicating their photodegradation and transformation. The resulting photoproducts were highly fluorescent, presenting a broad emission band around 520–540 nm. Oxygen reactive species did not seem to be produced in the principal photodegradation pathways, since photodegradation rates were similar to those in anaerobic samples. In the presence of O ₂ or N ₂ 1,6-DNP photodegraded 4 times faster than 1,8-DNP, while in the presence of water is 1.5 times faster. Two chromatographic fractions were separated, and identified as pyrenediones using authentic samples and reported spectral data for hydroxy-nitropyrenes. Other chromatographic fractions are still to be identified. The properties of the identified products suggested that these were formed through a nitro-nitrite rearrangement.     

A COMPARISON OF HPLC WITH FLUORESCENCE DETECTION AND FIXED WAVELENGTH FLUORESCENCE METHODS FOR THE DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBON METABOLITES IN FISH BILE

Fish exposed to polycyclic aromatic hydrocarbons (PAHs) accumulate only a small amount of PAH in their tissues. Hydrophobic PAHs are readily transformed into hydrophilic metabolites and excreted in bile. Bile samples of five fish species were collected from the Baltic Sea and analyzed using two methods: high-performance liquid chromatography (HPLC) with fluorescence detection and a fixed wavelength fluorescence method. With the HPLC method PAH compounds were quantitated after hydrolysis, and with the fluorescence method without enzyme-assisted hydrolysis. In HPLC analysis the major metabolite in all fish species, 1-hydroxypyrene, was the only metabolite detected in perch and salmon samples. 1-Hydroxyphenanthrene was detected in a few flounder and in most eelpouts. The correlation between the two methods for pyrene-type metabolites was good (r² = 0.773).