Authors:A. Ponomarenko, C. Klason, N. Kazantseva, M. Buzin, M. Alexandre, Ph. Dubois, I. Tchmutin, V. Shevchenko, and R. Jérôme
Thermogravimetry was used to investigate the effects of different inorganic functional fillers on the heat resistance of polymer
matrices. The kinetic parameters of thermal oxidative degradation were shown to depend on the polymer, the chemical composition
of the filler surface, the filler concentration, and the processing method, which determines the distribution of filler particles
in the polymer matrix. Magnetic fillers (carbonyl iron, and hexaferrites of different structural types) were shown to be chemically
active fillers, increasing the heat resistance of siliconorganic polymers. Their stabilizing effect is due to blocking of
the end silanol groups and macroradicals by the surface of the filler and non-chain inhibition of thermal oxidative degradation.
In the case of fiber-forming polymers (UHMWPE, PVOH and PAN), most magnetic fillers are chemically inert, but at concentrations
of 30–50 vol% they increase the heat resistance of the composite. Addition of carbon black increased the heat resistance of
the thermoplastic matrix. The dependence of the thermal degradation onset temperature on the kaolin concentration in the polyolefin
matrix exhibited a maximum. Analysis of the experimental results demonstrated the operating temperature ranges for different
composites, and their maximum operating temperature.
Authors:Jin Kim, Hyung Lee, Jei-Won Yeon, Yongju Jung, and Ji Kim
High surface area, ordered nanoporous carbon (CMK-3) and its chelating polymer composites were successfully prepared and utilized
for the removal of U(VI) from aqueous solutions. Carboxymethylated polyethyleneimine (CMPEI) with a strong chelating property
was introduced to the pore surface and inner pores of CMK-3 substrate. CMPEI-modified CMK-3 composite (CMPEI/CMK-3) was characterized
by scanning electron microscopy and nitrogen sorption. U(VI) sorption capacity was significantly improved by the surface modification
of CMK-3 by CMPEI. The CMPEI/CMK-3 showed enormously increased sorption capacities, compared with those of previous sorbents
(e.g., surface-functionalized silicas). In particular, the CMPEI/CMK-3 showed a significantly high uranium retention property
while allowing only about 1% U(VI) to leach out over a 4 month time period, when treated with polyacrylic acid.
Authors:A. A. El-Zahhar, H. M. Abdel-Aziz, and T. Siyam
The ion-exchange and sorption characteristics of new polymeric composite resins, prepared by gamma radiation were experimentally
studied. The composite resins show high uptake for Co(II) and Eu(III) ions in aqueous solutions in a wide range of pH. The
selectivity of the resins for Co(II) or Eu(III) species in presence of some competing ions and complexing agents (as Na+, Fe3+, EDTANa2, etc.) was compared. Various factors that could affect the sorption behavior of metal ions (Co(II) and Eu(III)) on the prepared
polymeric composite resins were studied such as ionic strength, contact time, volume mass ratio.
Authors:Alper Kiziltas, Douglas J. Gardner, Yousoo Han, and Han-Seung Yang
and destroyed each year globally [ 1 , 2 ]. Over the last few decades, interest in producing polymercomposite materials with cellulose materials has received considerable attention [ 3 – 7 ]. Polymercomposites with cellulose fibers are materials
Thermoset polymercomposites are preferred for many applications because of their strength, dimensional stability, resistance to heat, solvents and corrosive environments. They usually have a high glass transition
A novel macroporous silica-based 2,6-bis(5,6-diisobutyl-1,2,4-triazine-3-yl)pyridine (iso-Bu-BTP), a neutral chelating agent
having several softatom nitrogen, polymeric composite (iso-Bu-BTP/SiO2-P) was synthesized. It was done through impregnation and immobilization of iso-Bu-BTP molecule into the pores of SiO2-P particles with 40–60 μm of bead diameter and 0.6 μm of mean pore size. The effective impregnation resulted from the intermolecular
interaction of iso-Bu-BTP and co-polymer inside the SiO2-P particles by a vacuum sucking technique. To understand the possibility of applying iso-Bu-BTP in the MAREC process developed,
the adsorption behavior of a few representative rare earths (REs) such as Ce(III), Nd(III), Gd(III), Dy(III), Er(III), Yb(III),
and Y(III) towards iso-Bu-BTP/SiO2-P was investigated at 298 K. The influence of the HNO3 concentration in a wide range of pH 5.52–3.0M and a few chelating agents such as formic acid, citric acid, and diethylenetriaminepentaacetic
acid (DTPA) on the adsorption of RE(III) was examined. It was found that in the presence of chelating agent, the adsorption
ability of the tested RE(III) towards iso-Bu-BTP/SiO2-P decreased due to two competition reactions of RE(III) with iso-Bu-BTP/SiO2-P and chelating agents. In a 0.01M HNO3 solution containing 1M formic acid or 1M citric acid, light RE(III) showed lower adsorption towards iso-Bu-BTP/SiO2-P than that of the heavy one. This makes the separation of light RE(III) from the heavy one possible. Based on the similarity
of minor actinides and heavy RE(III) in chemical properties and the results of column separation experiments, chromatographic
partitioning of light RE(III) from a simulated high level liquid waste solution composed of the heavy RE(III) and minor actinides
in MAREC process is promising.
Authors:H.-S. Kim, H.-S. Yang, H.-J. Kim, and H.-J. Park
The thermal degradation and thermal stability of rice husk flour (RHF) filled polypropylene (PP) and high-density polyethylene
(HDPE) composites in a nitrogen atmosphere were studied using thermogravimetric analysis. The thermal stability of pure PP
and HDPE was found to be higher than that of wood flour (WF) and RHF. As the content of RHF increased, the thermal stability
of the composites decreased and the ash content increased. The activation energy of the RHF filled PP composites increased
slowly in the initial stage until α=0.3 (30% of thermal degradation region) and thereafter remained almost constant, whereas
that of the RHF filled HDPE composites decreased at between 30 and 40 mass% of RHF content. The activation energy of the composites
was found to depend on the dispersion and interfacial adhesion of RHF in the PP and HDPE matrix polymers.