Determination of inorganic constituents and polymers in metallized plastic materials

This work presents results obtained in the analyses of metallized plastics by neutron activation analysis (NAA) and results of polymer identification by infrared spectroscopy (IR) and differential scanning calorimetry (DSC). Metallized plastics of packagings, automobile accessories, toys, house wares, cards and compact discs were selected for these analyses. Toxic elements such as As, Cd, Cr, Ni, Sb and Sn as well as Ba, Br, Ca, Co, Fe, Sc, Se, and Zn were determined and their concentrations presented great variability. IR and DSC assays indicated that polyethylene, polypropylene, poly(ethylene terephthalate), polycarbonate, acrylonitrile-butadiene-styrene terpolymer are main types of polymers used in metallized plastics.     

Thermal Analysis of Ionizing Radiation Effects on Recycled Polyamide-6

The aim of this work is to study the ionizing radiation effects on thermal properties of there cycled polyamide-6. This polymer was irradiated with an electron beam of 1.5 MeV with different doses. The thermal properties of the samples were determined by TG, DSC and DMA measurements. It was observed that the irradiated samples of recycled polyamide-6undergo a crosslinking process. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preliminary analysis to BIIR recovery using the microwave process

This paper shows the results of preliminary assessment to devulcanize and recover the bromobutyl rubber (BIIR) using the microwave process. In this work, a heat generating system with high microwave frequency (2.45 GHz) was used. Samples of BIIR (about 0.250 kg) such as rubber caps production leftovers and materials that had not been approved in the quality tests were irradiated, at powers of 1000 W, 2000 W and 3000 W. Various heating times were used: 540 s (9  min) up to 1500 s (25 min). The standard test specimens of non-irradiated and irradiated samples were characterized by rheometric analysis, Shore A hardness measurement and ash test. The best operation conditions were obtained at 780 s and 2000 W. The results showed that the microwave process caused an expressive effect in the BIIR recovery. Some samples presented the tendency to vulcanize again, hence there is a great expectancy for reusing and recycling the devulcanized BIIR, without using any chemical agent in the microwave process.     

Biodegradable Poly(3-hydroxybutyrate) Nanocomposite

This work seeks bringing a technological and social contribution by searching blends and composites of poly(3-hydroxybutyrate) (PHB) and polyethylene widely used in packaging films, and colloidal silica. The mixtures were prepared by extrusion using a single-screw extruder and were analyzed regarding their thermal and mechanical properties and morphology. The results have shown PHB toughness in the studied compositions, which elongation at break was in the range 5–80% compared to 2% for neat PHB. The small amount (0.2 to 0.4%) of added silica seemed to increase in 20% the tensile strength. The thermal degradation by thermogravimetry from room temperature to 800 °C revealed a mixed behavior for the composites between PHB and polyethylene.     

Study of the influence of graphite content on polysulfone-graphite composite membrane properties

Techniques such as plasma treatment and electrophilic aromatic substitution are strategies commonly used to increase membrane hydrophilicity. We here suggest the addition of graphite (the contents of 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mass%) in the system composed of polysulfone/N-methyl-2-pyrrolidone/water and, consequently, the formation of a composite membrane as a method to increase membrane hydrophilicity. Polysulfone-graphite membranes were prepared by wet-phase inversion method and were compared to that of pristine polysulfone membrane. From X-ray diffraction and Fourier transform infrared spectroscopy, it was observed that the structures of both starting materials were maintained. Scanning electron microscopy images revealed a cellular morphology of both membranes and the presence of graphite particles in the cross-sectional area. Contact angle measurements showed that Lewis acid-base interactions were favored by graphite addition and membrane hydrophilicity increased by increasing the graphite content except for the membrane prepared from a dispersion containing 3.0 mass% graphite. By increasing the graphite content, the onset temperature of degradation was increased and mass loss was decreased whereas only the membranes with low graphite content presented an increase in glass transition temperature. Finally, from tensile tests, it was noted that the presence of graphite particles resulted in the brittleness of the composite membranes.