A simple pre-irradiation procedure for the separation of iodine from soil has been developed. A soil sample was heated in a quartz tube for 15 min at about 900 °C. The evaporated iodine was collected in activated charcoal, which was produced from phenol resin with low impurities. The charcoal, with sorbed iodine, was irradiated by neutrons and the128I produced was measured. A successful elimination of the background radioactivity due to the matrix elements was possible with this separation procedure. The detection limit by this method for soil samples was about 0.1 mg/kg (dry). The method has been applied to analyze selected soil samples.
Authors:B. Kubica, H. Godunowa, M. Tuteja-Krysa, M. Stobiński, and R. Misiak
Sorption of lead(II) on very poorly soluble hexacyanoferrates(II) of transition metals: CuII, NiII, ZnII, CoII and on the ion-exchange composite obtained by mixing of nickel(II)-potassium hexacyanoferrate(II) with sulfonated phenolic resin serving as matrix was studied. Sorption was performed from solutions of hydrochloric acid at concentrations ranging from 10–4 to 10–1 mol·dm–3. Analytical distribution coefficients for lead(II) sorption on these adsorbents were determined. Lead(II) sorption on Dowex 50 and the composite resin was studied as well.
A reliable method for the sampling and analysis of atmospheric iodine species was developed. The air filtering system consisted of a 0.4 m Nuclepore® filter, 47 mm in diameter, for particulate collection followed by two, 47 mm in diameter, cellulose filters for inorganic iodine collection. The latter filters had been impregnated with 1N LiOH in a 10% glycerol-water mixture. The organic iodine was collected by two beds holding 0.2 g of fibriform activated charcoal produced from phenol resin. Supplementation of the charcoal with triethylendiamine (TEDA) enhanced the sorption ability for gaseous iodine. The filters were analyzed by neutron activation analysis. The background radioactivity could be reduced by using the fibriform activated charcoal due to the low content of impurities in the phenol resin. The background count for128I (443 keV) obtained from the fibriform activated charcoal was about one order of magnitude lower than that of the conventional granular one (plant origin). Approximate detection limits for particulate, inorganic and organic iodine were 1, 0.5 and 0.5 ng/m3, respectively, when 50 m3 of air was sampled by this system. The air was sampled at two locations along the coast of Ibaraki, Japan. The concentration ranges of particulate, inorganic and organic iodine were 0.3–3.4, 1.2–3.3 and 7.8–20.4 ng/m3, respectively. Almost 90% of the atmospheric iodine was in a gaseous form in which organic iodine was dominant.
Authors:R. Ozao, T. Okabe, T. Arii, Y. Nishimoto, Y. Cao, N. Whitely, and W.-P. Pan
Summary An odorless woodceramics (CH800), which was prepared by carbonizing chicken wastes with phenolic resin, was characterized by XRD and thermal analysis. CH800 was found to consist mainly of amorphous carbon (non-graphitizing carbon) as studied by XRD. Differing from carbonized chicken waste, CH800 was completely free of unfavorable smell. The source of strong smell of carbonized chicken waste was studied by using TG-DTA combined with EGA technique using gas chromatography and mass spectrometry (TG-DTA/GC-MS). As a result, it was found that CH800 was completely free of compounds having strong smell, i.e., ethanol, acetonitrile, pyridine, styrene, benzonitrile and benzofuran, whereas carbonized chicken waste contained all of these compounds.
Authors:N. Gabilondo, M. López, J. Ramos, J. Echeverría, and I. Mondragon
The effect of both formaldehyde content and catalyst type used in the synthesis of several resole type phenolic resins has
been studied by using differential scanning calorimetry. In this study Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW)
and Friedman model-free kinetics are applied in order to correlate the dynamic cure behaviour with the mentioned synthesis
variables. Strong upward dependency of activation energy on conversion has been detected in all cases up to a maximum value.
Lower the formaldehyde content fewer changes in activation energy have been detected, revealing a more homogeneous polymerization.
As formaldehyde content increases, stronger variations of energy values have been observed and the maximum value is shifted
to lower conversions. By comparing triethylamine and sodium hydroxide catalysts similar behaviour has been observed, with
higher energy values and shifting of the maximum in the latter. Friedman approach has been resulted in more convenient and
accurate for the energy values determination and KAS method seems useful for the dynamic cure prediction of that type of thermoset.
This article aims to modify conventional epoxy resin by blending with four different Mannich base oligomers. These oligomers
are similar to phenolic resin matrix and simultaneously function as amino curing agent for epoxy matrix. In this context,
Mannich base oligomers were prepared, respectively, by Mannich polycondensation reaction of four phenols namely phenol, m-cresol, resorcinol and 1,5-dihydroxy naphthalene, respectively, with formaldehyde and piperazine in presence of acid catalyst.
The resulting oligomers were characterized by elemental analysis, spectral studies (IR and NMR), number average molecular
estimated by non-aqueous conductometric titration and thermal stability by thermogravimetric analysis (TG). Each of these
oligomers was used in resin matrix as a blending component for the modification of commercial epoxy resin for fabricating
glass fibre reinforced laminates. Finally, these laminates were evaluated for their synergetic thermal stability, mechanical
properties and chemical resistance to different reagents.
Authors:W. -D. Emmerich, J. Janoschek, and E. Kaisersberger
Curing and decomposition of a phenolic resin is studied by simultaneous thermal analysis (STA) and mass spectrometry (MS) to get quantitative and qualitative information on the reactions. The influence of the heating rate and the curing mass loss of the same material is measured with a symmetrical micro thermobalance. A high temperature DSC apparatus is used to determine the specific heat of a glass ceramic. Poco graphite is used for expansion calibration measurements with a new dilatometer up to 2000 °C.
Authors:M. V. Alonso, M. Oliet, J. C. Domínguez, E. Rojo, and F. Rodríguez
of which is subject to fluctuations in the price of oil. Many researchers have presented as an attractive alternative the incorporation of natural polymers such as lignin, lignin derivative, and tannins in the formulation of phenolicresins [ 1 – 3
Authors:Bimlesh Lochab, Indra K. Varma, and Jayashree Bijwe
Polybenzoxazines (PBzs), a new class of thermosetting resins, first reported in 1994 [ 1 ] are gaining attention due to better performance than the state-of-the-art phenolicresins. The advantages [ 2 – 4 ] of PBzs