The mechanics of thermally-activated gaseous diffusion in polymers have long been studied for development of theoretical understanding
of the interactive forces responsible for the non-linear nature of diffusion and the resultant enthalpic changes in the polymer.
Methodologies and calculations have been developed in this work for treatment of experimental data for elimination of thickness-related
anomalies in water vapor diffusion and for delineation of pressure effects. Linearized data for different polymer thicknesses
and the attendant internal thermal effects have been generated by using calculated single molecule diffusion values. Equally
linear data are obtained for different pressures by the use of a graphical method from which identical diffusion values are
obtained, independent of material thickness and external pressure. True comparisons and classification of polymers as to their
diffusivities are thus possible for development of barrier materials for food and drug packaging and for protective encapsulation
of electronic devices.
Results will be reported for three structurally different polymers.
Authors:M. Gojić, J. Črnko, M. Sućeska, and M. Rajić
Heat treatment of pipes was performed under industrial conditions at 580C in a dry protective gas containing a CO2–CO–H2–N2 mixture. A commercial adsorbent (733 kg) used for production ofthe gas removed 52.7 l of water in five h and 22.5 min. During
the annealing of pipesoxidation and decarburization were not observed. The results were confirmed bymetallographic analysis.
The values of enthalpy of water desorption (36.4–40.5 kJ mol–1) obtained by DSC and TG measurements were close to those of water evaporation(44.1 kJ mol–1). This suggests that the bonds between the water molecules andadsorbents were not of chemical but of physical nature.
Authors:N. Ando, S. Tasaki, Y. Hato, C. Marumo, Y. Natsume, S. Ohmori, A. Ito, and K. Tanaka
The polyacenic semiconductive (PAS) material is a typical amorphous carbon prepared by pyrolysis of phenolformaldehyde resin,
and is actually utilized as anode of high-capacity rechargeable batteries. In this work, change in the discharging amount
of Li+ before and after heat-treatment of the PAS electrodes at the various doping level was examined in detail. As a result, the
doped Li can be classified into two types: (i) heat-resistant Li-dopant (or Li-dopant with high diffusion coefficient) and
(ii)heat-fragile Li-dopant (or Li-dopant with low diffusion coefficient). The latter Li-dopants are generated above the doping
level of 30% ([Li]/[C]→0.3) and is considered to be the origin of high-capacity of PAS anode compared with that of graphite
anode. This aspect is also supported by the ESR, 7Li-NMR, and XPS observation results.
Authors:Tamás Zsom, Petra Polgári, Lien Phuong Le Nguyen, Géza Hitka, and Viktória Zsom-Muha
materials, or ethylene scavenging agents) could serve effectively for these purposes. 1-MCP (1-methyl-cyclopropene) application as a novel postharvest treatment ( Blankenship & Dole, 2003 ) is proved to be effective against undesired postharvest ripening of
Mössbauer effect was used for the characterization of the radioactive waste treatment products, e.g. precipitate formed during the treatment of LLAW (Low Level Active Waste) using iron compounds and their conditioned matrix obtained by cementation.
Radiation treatment with gamma-rays was used to improve the biodegradability of EDTA that is known to be a non-biodegradable
substance. The effect of metal ions and catalysts on the treatment of EDTA was studied first. The removal of EDTA was definitely
decreased in the presence of metal ions such as Cr(III), Cd(II), Pb(II) and Cu(II) at doses greater than 3 kGy. The addition
of a TiO2
The possibility of applying chemical treatment prior to evaporation was discussed in the present work. Using titanium hydroxide-cobalt
ferrocyanide as coprecipitants allows fixation of high percentage of radioactive nuclides present (e.g. Cs 98%, Ru 90%, Sb
95%, Ce 98%, Am 95% and Pu 95%). Hence using such simple chemical separation before evaporation improves the process and leads
to several advantages, e.g. raising the decontamination factor, reducing radioactive aerosol production and solving the problem
of medium active waste treatment by adding the chemically precipitated solids to the high-active waste and the supernatant
to the low-active waste, are examples for these advantages.
Authors:H. J. Jo, S. M. Lee, H. J. Kim, J. G. Kim, J. S. Choi, Y. K. Park, and J. Jung
In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation
on biodegradability (BOD5/COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment
based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable
and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters,
gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such
as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This
may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp
wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However,
the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed
dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds
such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents.
Authors:J. L. Pérez-Rodríguez, F. Franco, V. Ramírez-Valle, and L. A. Pérez-Maqueda
The differences on the thermal behaviour (DTG-DTA) of antigorite sample measured before and after sonication have been studied.
Sonication treatment produces negligible changes in the structure of the material but substantial textural modifications.
These modifications produce changes in the thermal behaviour of antigorite sample. Thus, it has been observed a decrease in
the dehydroxylation temperature as measured by DTG and DTA effects. For sonication treatments longer than 20 h, two new effects
of dehydroxylation are observed, the intensity of these two new effects increases with the sonication time showing a modification
in the release of structural OH. It has been also observed that the formation of forsterite takes place simultaneously with
the dehydroxylation of the antigorite. The high temperature exothermic effect is due to the recrystallization of forsterite
and not to the formation of forsterite as traditionally assumed. Modifications in the thermal dehydroxylation of antigorite
observed in this study are related to the pronounced decrease in particle size obtained by sonication.