Oriana Motta

Utilization of chemically oxidized polystyrene as co-substrate by filamentous fungi.

Atactic polystyrene, one of the most widely used chemical products, was subjected to novel chemically oxidative treatments able to trigger a great variety of physical and chemical changes in the polymers chains. The oxidized polystyrene samples, when analyzed with Fourier transform infrared spectroscopy (FTIR) clearly showed the formation of carbonyl groups and hydroxyl groups, which increased with the increase in the strength of chemically oxidative treatments. In fungal degradation tests deploying Curvularia species, the fungus colonized the oxidized samples within 9 weeks. Colonization was confirmed by microscopic examination, which showed that the hyphae had adhered to and penetrated the polymers structure in all the treated samples. Such colonization and adhesion by microorganisms are a fundamental prerequisite for biodegradation of polymers.

Transport and mechanical properties of PET/ Rodrun 3000 blown films

Abstract Blends of different ratios of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polymer (TLCP) composed of 40 mol% of polyethyleneterephthalate and 60 mol% of p-hydroxybenzoic acid (Rodrun 3000) have been processed in a laboratory-based film-blowing extrusion apparatus. Gas permeability measurements have been performed on the films in order to evaluate the effect of the mesophase on the transport behaviour of PET films. The transport properties of the blends are dependent upon the state dispersion of the minor phase; thus, scanning electron microscopy has been conducted on the film surfaces to observe the morphological structure of the TLCP developed during the extrusion process. Moreover, the mechanical properties of the films at 2, 10 and 30% (w/w) TLCP contents have been examined in both the transverse and flow directions.

Processing-Structure-Properties Relationships in Blends with Thermotropic Liquid Crystalline Polymers

Abstract In this paper the effect of the inclusion of thermotropic liquid crystalline polymers (TLCP) in thermoplastic polymers is analyzed, with due attention to similar studies reported in the literature. Numerous results relative to TLCP containing blends are considered in terms of structure development in typical processing operations like extrusion and fiber spinning. Several systems have been studied in order to emphasize that different effects can be obtained as regards processing and mechanical properties of the host matrices. As for rheological aspects, it has been verified that TLCP can be considered as effective flow aids, even at low concentrations. The addition of a low percentage (5 to 10 %) of a TLCP with a viscosity lower than that of the matrix produces a significant reduction (25 to 40 %) in the blend viscosity. Moreover, mechanical results have shown that an improvement of the matrix rigidity can be obtained, especially at high percentages of TLCP (30 %), under processing conditions where a highly extensional flow prevails. However, a decrease in the ultimate elongation of the matrices has been found in all systems where a poor adhesion between the two phases exists.

Thermal behaviour of the PET/Rodrun 3000 system

The crystallization behaviour of poly(ethylene terephthalate) (PET) and its blends with a liquid crystal polymer (Rodrun 3000) was studied by differential scanning calorimetry (d.s.c.), under both non-isothermal and isothermal conditions. The theories of Ozawa and Avrami were applied to study the kinetics of non-isothermal and isothermal crystallization respectively. In both cases it was found that a very low percentage of a thermotropic liquid crystal polymer (TLCP) determines an increase in the overall crystallization rate, while increasing the amount of TLCP results in a progressive decrease in the crystallization rate and the melting temperature. However, the crystallinity of PET in the blends was found to increase on increasing the TLCP content.

Synthesis and physical properties of elastomeric polypropylene obtained in the presence of TiCl2(2-OC6H4OCH3)2 and methylaluminoxane

Abstract In this work we present a new synthetic route to obtain elastomeric polypropylene with high molecular weight and narrow molecular weight distribution, in the presence of TiCl 2 (2-OC 6 H 4 OCH 3 ) 2 and methylaluminoxane catalytic system. Moreover we focused on investigating the thermal, mechanical and rheological properties of the ELPP and its solvent fractions. The results demonstrate that the polymers exhibit high ultimate extension and excellent elastic recovery, due to the presence of microcrystalline domains dispersed in the amorphous phase. The elastic and viscous response has been found to depend upon the molecular weight, which changes with the polymerization temperature.

Assessment of perchlorate-reducing bacteria in a highly polluted river.

A 1-year monitoring experiment of the Sarno River basin was conducted during 2008 to evaluate the overall quality of the water over time and to compare the results with those obtained previously. The physico-chemical and microbiological characteristics of the water course had not changed appreciably with respect to previous determinations, thus emphasizing the major contribution of untreated urban wastewater to the overall pollution of the river. Moreover, attention was paid to the perchlorate ion, one of the so-called emerging contaminants, which is widespread in natural environments and is known to have adverse effects on the human thyroid gland. Over the entire monitoring program, we did not find appreciable levels of perchlorate, although the particular environmental condition could support its development. Thus, a dedicated study was designed to assess the presence of bacteria that can reasonably reduce perchlorate levels. By enrichment and molecular procedures, we identified α- and β-Proteobacteria strains, classified by 16S rDNA sequences as Dechlorospirillum sp. and Dechlorosoma sp., respectively. Further physiologic characterization and the presence of the alpha subunit gene (pcrA) of the perchlorate reductase in both strains confirmed the presence in the river of viable and active perchlorate dissimilatory bacteria.

An improved method for BTEX extraction from charcoal

In this paper we propose a simple procedure for the extraction of BTEX (benzene, toluene, ethylbenzene and xylenes) from activated charcoal. For this purpose synthetic samples were prepared in a laboratory and real samples were collected in a polluted environment using passive sampling. The proposed extraction procedure is based on the use of an appositely designed Soxhlet apparatus, dimensions of which are as small as the cartridge of the passive samplers, in order to accommodate this latter and permit us to use a small amount of solvent. The selection of the solvent was based on the strong desire to substitute carbon disulfide, which is by far the solvent of choice, with a less hazardous substance in order to enhance operator protection. Among the solvents tested the best results were obtained by using dichloromethane that, under optimized conditions, led to a complete recovery (>97%) of each analyte (BTEX), both in the synthetic and the real samples. The extraction procedure with CH2Cl2 in the Soxhlet lasted for about 20 minutes which also resulted in a reduced operating time.

Oxidation of saturated and unsaturated alcohols promoted by aluminum alkyls and t-butyl hydroperoxide

Saturated and unsaturated alcohols are efficiently converted into the corresponding ketones and epoxy-alcohols by treatment with organic aluminium compounds/t-butyl hydroperoxide systems. In this paper, we have exploited the possibility of using some commercial aluminium alkyls as catalysts for oxidation reactions. Then, since we observed that the increase of alkyls hindrance on aluminium enhances the conversion toward oxidated products, we found of interest to synthesize a more hindered aluminium based compound. The catalytic performance of this latter compound toward oxidation reactions of allylic alcohols was tested and it was found that it is the most attractive both in terms of yield and time of reaction.

New FTIR methodology for the evaluation of 13C/12C isotope ratio in Helicobacter pylori infection diagnosis

OBJECTIVES The objective of this work was to assess the reliability of a newly developed FTIR (Fourier Transform Infrared spectroscopy) technique for (13)C-urea breath test in the non-invasive diagnosis of Helicobacter pylori infection, in comparison to those currently used, isotope ratio mass spectrometry (IRMS) and non-dispersive isotope-selective infrared spectrometry (NDIRS). This new methodology is based on the use of a very less expensive and sophisticated FTIR than IRMS and NDIRS. MATERIALS AND METHODS Sixty patients (male and female, aged between 15-70 years) with dyspeptic symptoms, like the epigastric pain, were tested for H. pylori infection using (13)C-urea breath test. Triplicate breath samples were collected before and 30 min after drinking the test solution (75 mg (13)C-urea dissolved in 200 ml 0.1M citric acid). Analysis of delta(13)C were conducted in parallel by means of IRMS, NDIRS and FTIR in order to compare the results. RESULTS Delta-over-baseline values were over 5 per thousand in 18 patients, ranging from 8.81 to 60.88 per thousand for IRMS measurements, from 7.2 to 61.2 per thousand for NDIRS and from 7.7 to 61.2 per thousand for FTIR measurements. The remaining 42 subjects had values well below the 5 per thousand cut-off. The results of the baseline-corrected (13)CO(2) exhalation values between FTIR and IRMS/NDIRS were in good agreement. CONCLUSIONS The newly developed FTIR methodology has been demonstrated to be a reliable and accurate analytical tool, low cost and easy-to-operate, which permits a highly specific measurement of (13)C enrichment in breath samples. As IRMS and NDIRS it allows to adequately discriminate between infected and non-infected subjects.

ZrCl4(THF)2/Methylaluminoxane as the catalyst for the syndiotactic polymerization of styrene

The presence of an organic Lewis base, such as THF, enhances the syndiospecificity of the catalytic system ZrCl 4 /methylaluminoxane toward the polymerization of styrene. The polymer has low molecular weight and a microstructure similar to other polystyrenes obtained with zirconium-based catalysts.