Removal of lead compounds from polyvinylchloride in electric wires and cables using cation-exchange resin

Recycling treatment of cable insulation resin generated from electric wires and cables was investigated. Conventional insulation PVC contains a lead component, tribase, as a thermal stabilizer and lead removal is necessary to recycle this PVC as insulation resin. This paper describes a solid surface adsorption method using ion exchange resin to remove the fine lead containing particles from PVC dissolved solution. Low lead concentration in the recovered PVC, complying with the requirements of RoHS, was achieved.     

Transient hopping transport in percolation clusters

Monte Carlo simulation for percolative hopping transport has been carried out to explain the increase in transit‐time dispersion and decrease in drift mobility with increasing applied electric field, found in molecularly doped polymers with low concentrations of charge transporting molecules. These two phenomena cannot be understood in terms of the Gaussian disorder model (GDM), which has been widely accepted for the analysis of the transport data of molecularly doped polymers. It is found that the two phenomena are successfully explained by the present computer simulation. The GDM analysis is applied to the analysis of the simulation data, and it is shown that energetic disorder can be estimated from the GDM analysis even in the case of percolative hopping transport and that the percolative motion of hopping carriers is one of the origins of geometrical disorder. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 1–9, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10014     

Flame retardancy effects of halogenated phosphates on poly(ethylene terephthalate) fabric

A Chemical research on the flame retardancy effect of halogenated phosphates on poly(ethylene terephathalate) fabric was carried out by thermogravimetry, infrared spectral analysis, and mass spectrometry. The following conclusions were drawn: (1) The flame retardancy effect of halogenated phosphates such as tris(2,3-dibromopropyl) phosphate is due to altering the pyrolysis reaction of polyester by aldol condensation. (2) The probability that liberated halogen compounds from the phosphates act as radical acceptors in a flame zone may be low. (3) Incorporation of halogen elements into phosphates appear to depress evaporation of phosphates, which act as acidic catalysts in aldol condensation from the condensed phase.     

Effect of Milling Treatment on the Particle Size in the Preparation of AIN Powder from Aluminum Polynuclear Complexes

Aluminum nitride powder was synthesized from aluminum polynuclear complexes. Basic aluminum chloride (BAC) provided the aluminum polynuclear complexes. The effect of the milling treatment for the precursor made from basic aluminum chloride and glucose on the particle size was investigated. BAC and glucose were dissolved in water and mixed homogeneously. AIN powder was obtained by calcining under a nitrogen gas flow after drying, milling by vibration mill, and precalcining at 800°C. Then excess carbon was removed by firing in air. It was found that the milling treatment affected the particle size of AIN powder and nitridation mechanism. Without the milling treatment, AIN powder was synthesized directly from the γ-alumina of an intermediate product. In using a milled precursor, however, α-alumina was formed during the calcining, and the particle size of the AIN powder obtained was about five times larger than that of AIN powder synthesized from a raw precursor. The formation of α-alumina phase began at the rather low temperature of 800°C. These results suggest that the mechanochemical effects added by the milling promotes the formation of α-alumina during calcining, and the α-alumina phase formed accelerates the particle growth. AIN powders obtained were very uniform. The oxygen content and the surface area of AIN powders synthesized from the raw and milled precursors were 2.9 wt% and 17.5 m²/g, and 1.1 wt% and 3.6 m²/g, respectively.     

Preparation and cured properties of novel cycloaliphatic epoxy resins

Preparation and characterization of novel cycloaliphatic epoxy resins, which are derived from octadienyl compounds, were studied. From a model peracetic acid epoxidation reaction using 2,7-octadienyl acetate-1, the structure of the liquid resins is estimated to be mainly terminal epoxides and some amount of inner epoxide depending on the epoxide content. The epoxy resins offer lower toxicity and lower vapor pressure. The reactivity of the resin with acid anhydrides is moderate but faster than that of traditional cyclohexane epoxide-type resins and slower than that of the glycidyl ester-type resins. This reactivity was also examined using model compounds. The heat deflection temperature of the hexahydro-phthalic anhydride-cured resins is shown to be directly proportional to the number of epoxy groups in the molecules. The flexural strength of the cured resins is nearly equivalent to that of the commercial resins, although the flexural elongation of the resins is larger than that of the rigid cyclohexane epoxide-type resins. The thermal stability of the cured resins is comparable to typical rigid cycloaliphatic resins; furthermore, high water resistance of the cured resins is suggested to be attributed to the hydrophobic character of the C₈ chain by cross-linking. © 1993 John Wiley & Sons, Inc.     

Capacity fading with oxygen loss for manganese spinels upon cycling at elevated temperatures

The nominal LiMn₂O₄ and Li-doped spinels with different oxygen stoichiometry were prepared and investigated for capacity fading upon cycling at elevated temperatures. The discharge plateau at 3.2 V originating from oxygen defects in manganese spinels is observed to grow very quickly to nearly a maximum scale in initial 15 cycles at 60 °C. Meanwhile, the majority of capacity fading is lost. Therefore, the quick capacity fading in the initial stage is associated with the increase of oxygen deficiencies or oxygen loss upon cycling. It is proposed that the oxygen loss is originated from the decomposition of instable spinel phases that containing little Li cations on the 8a sites ([□₁]_8a[Mn_2−x]_16d[O_4−δ□_δ]_32e, etc.), which are formed upon charging to the upper voltage limit. This phenomenon is much severe for nominal LiMn₂O₄ spinels with oxygen deficiencies. After partial substitution of Mn with Li, part of the Li cations on the 8a sites will be retained upon charging to the upper voltage limit. Thereafter, the cycling performance can be improved for the stabilized spinel phases formed upon charging.     

Analysis of time-of-flight transient photocurrent in organic semiconductors with coplanar-blocking-electrodes configuration

Time-of-flight transient photocurrent in organic semiconductors with coplanar-blocking-electrodes configuration has been numerically analyzed. Time-of-flight measurements for such a sample configuration enable us to determine the drift mobilities of organic semiconducting materials applicable to organic field effect transistors. It is shown that the charge-carrier transit time can be determined in both non-dispersive and dispersive transport under the condition that the charge-carrier transit time is much shorter than the monomolecular and bimolecular recombination lifetimes. It is also shown that the localized-state distributions can be determined from the analysis of the transient photocurrent.     

A mathematical model for computer simulation of the direct continuous esterification process between terephthalic acid and ethylene glycol. Part II: Reaction rate constants

It has been confirmed that the reaction model proposed previously, which can express simultaneously the oligomer properties and the distillate properties under low esterification pressure, is applicable to a continuous direct esterification process in a practical plant. The experimental data of the first esterification reactor (RA-1) was obtained under low reaction pressures (atomospheric or 1 kg/cm²G) with the pilot plant throughput based on poly(ethylene terephthalate) (PET) polymer production of about 50 kg/h. The Arrhenius' parameters, frequency factor, and apparent activation energy, were determined fitting the experimental data of the pilot plant by using the Simplex method as an optimization technique. The activation energy of diethylene glycol (DEG) formation, E₇, is about twice as much as those of the esterifications, E₁, E₂, E₃, and E₄. The activation energies are E₁, = 19640 cal/mol, E₂ = 18140, E₃ = 22310, E₄ = 18380, E₅ = 2810, E₆ = 14960, and E₇ = 42520 cal/mol. Good agreement was obtained between experimental data and calculated predictions for several oligomer and distillate properties. The vapor-liquid equilibrium can be expressed by Raoult's law with little problem of practical use.     

Friedel-Crafts Acylation of Anisole with Carboxylic Anhydrides of Large Molecular Sizes on Mesoporous Silica Catalyst

The titled reaction was well catalyzed on mesoporous silica MCM-41. The acylation of anisole with carboxylic anhydrides of large molecular sizes such as hexanoic anhydride and benzoic anhydride proceeded with excellent or good yields at 453 K, while the small molecules including propionic and acetic anhydrides gave moderate yields. The presence of nano-sized pores of MCM-41 was essential to generate the catalytic activity while the Al content showed little effect on the catalysis.     

Studies on local structure in hydrogenated amorphous LaNi5.0 films using extended X-ray absorption fine structure

The local structure in hydrogenated amorphous LaNi_5.0 film was analysed by means of extended X-ray absorption fine structure. The short-range order in the amorphous LaNi_5.0 film was found to be little affected by the absorption of hydrogen. The lengthening of the interatomic distance with an increase in hydrogen concentration was much smaller for an amorphous film than for a crystalline bulk, so that the amorphous film appears to have excellent durability with regard to the hydrogen absorption-desorption process.