Sara Filippi

Recovery of vanadium from heavy oil and Orimulsion fly ashes

This work concerns a three-step process for the recovery of vanadium from heavy oil and Orimulsion combustion fly ashes. This consisted of acid leaching, oxidation and precipitation of the vanadium pentoxide, followed by washing of the precipitate. Preliminary tests were conducted to investigate the effect of some operating parameters for the various steps of the process. After these preliminary tests, the recovery of vanadium from the fly ash samples was performed on a laboratory scale and the overall yield of the process was determined. By washing the precipitate, it was possible to reduce the concentration of the impurities and to allow its use for the production of ferrovanadium alloys.

A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility

During the last decades, the number of vehicles per citizen as well as the traffic speed and load has dramatically increased. This sudden and somehow unplanned overloading has strongly shortened the life of pavements and increased its cost of maintenance and risks to users. In order to limit the deterioration of road networks, it is necessary to improve the quality and performance of pavements, which was achieved through the addition of a polymer to the bituminous binder. Since their introduction, polymer-modified asphalts have gained in importance during the second half of the twentieth century, and they now play a fundamental role in the field of road paving. With high-temperature and high-shear mixing with asphalt, the polymer incorporates asphalt molecules, thereby forming a swallowed network that involves the entire binder and results in a significant improvement of the viscoelastic properties in comparison with those of the unmodified binder. Such a process encounters the well-known difficulties related to the poor solubility of polymers, which limits the number of macromolecules able to not only form such a structure but also maintain it during high-temperature storage in static conditions, which may be necessary before laying the binder. Therefore, polymer-modified asphalts have been the subject of numerous studies aimed to understand and optimize their structure and storage stability, which gradually attracted polymer scientists into this field that was initially explored by civil engineers. The analytical techniques of polymer science have been applied to polymer-modified asphalts, which resulted in a good understanding of their internal structure. Nevertheless, the complexity and variability of asphalt composition rendered it nearly impossible to generalize the results and univocally predict the properties of a given polymer/asphalt pair. The aim of this paper is to review these aspects of polymer-modified asphalts. Together with a brief description of the specification and techniques proposed to quantify the storage stability, state-of-the-art knowledge about the internal structure and morphology of polymer-modified asphalts is presented. Moreover, the chemical, physical, and processing solutions suggested in the scientific and patent literature to improve storage stability are extensively discussed, with particular attention to an emerging class of asphalt binders in which the technologies of polymer-modified asphalts and polymer nanocomposites are combined. These polymer-modified asphalt nanocomposites have been introduced less than ten years ago and still do not meet the requirements of industrial practice, but they may constitute a solution for both the performance and storage requirements.

Reactive Compatibilizer Precursors for LDPE/PA6 Blends, 1 Ethylene/Acrylic Acid Copolymers

Ethylene/acrylic acid copolymers (EAA) with different acrylic acid (AA) contents have been used as compatibilizer precursors (CPs) for blends of two grades of lowdensity polyethylene (LDPE) with polyamide-6 (PA). In the first part of the work, binary blends of the CPs with LDPE and with PA have been studied in order to get an insight into the interactions of the EAA copolymers with the blends components. It has been shown that the CPs form immiscible, yet highly compatible, blends with LDPE. Investigation of the binary CP/PA blends provided evidence that acidolysis reactions occur between the carboxyl groups of the CPs and the amine and amide groups of PA, with formation of CP/PA graft (CP-g-PA) copolymers, although these reactions need relatively long times to go to completion. In the second part of the work, ternary LDPE/PA/CP blends have been prepared and characterized with a number of techniques. It has been shown that the addition of only 1-2 phr of CP into the LDPE/ PA blends is sufficient to enhance interfacial adhesion, to improve the minor phase droplet dispersion and to hinder coalescence. The effectiveness of the investigated CPs increases with an increase of the AA content from 6 to 11 wt.-%. Partial neutralization of the carboxyl groups of EAA with zinc also seems to improve the CP efficiency and this effect is thought to result from an acceleration of the acidolysis reactions responsible for the formation of CP-g-PA copolymers.

Reactive compatibilizer precursors for LDPE/PA6 blends. III: ethylene–glycidylmethacrylate copolymer

Abstract The effectiveness of a commercial ethylene–glycidylmethacrylate copolymer (Lotader GMA AX 8840) as a compatibilizer precursor (CP) for blends of low density polyethylene (LDPE) with polyamide-6 (PA) has been evaluated by an investigation of the thermal properties and the morphology of binary (LDPE/CP and PA/CP) and ternary (LDPE/PA/CP) blends, as well as by solvent fractionation experiments. It has been demonstrated that the epoxy groups of the CP react quite easily, during melt blending, with both the amine and the carboxyl end groups of PA to give CP-g-PA copolymers, which, depending on the relative amounts of PA and CP, may be partially cross-linked. The composition of the graft copolymers has been approximately determined by gravimetric and calorimetric measurements. The compatibilizing efficiency of the CP employed in this work has been found to be comparable to that of the ethylene–acrylic acid copolymers, and lower than that of a maleic anhydride-functionalized polyethylene, which had been used in previous works.

Oxazoline functionalization of polyethylenes and their blends with polyamides and polyesters

The compatibilization of blends of polyamide-6 (PA6) with linear low density polyethylene (LLDPE) and of poly(ethylene terephthalate) (PET) with high density polyethylene (HDPE), by functionalization of the polyethylenes with oxazoline groups was investigated. Chemical modification of LLDPE and HDPE was carried out by melt free radical grafting with ricinoloxazoline maleinate. Blends preparation was made either with a two-steps procedure comprising functionalization and blending, and in a single step in which the chemical modification of polyethylene with the oxazoline monomer was realized in situ, during blending. The characterization of the products was carried out by FTIR spectroscopy and scanning electron microscopy (SEM). The rheological and mechanical properties of the blends were also investigated. The results show that functionalization of the polyethylenes can be achieved by melt blending with ricinoloxazoline maleinate even in the absence of free radical initiators. The compatibilization of the blends enhances the dispersion of the minor phase significantly, increases the melt viscosity, and improves the mechanical properties. The one-step preparation of the compatibilized blends was also found to be effective, and is thought to be even more promising in view of commercial application.

Coupling of chiral 1-bromo-1,2-dienes with zinc-based cuprates: a new procedure for the regio and stereoselective synthesis of functionalized acetylenic compounds

Abstract Zinc alkylcyanocuprates (Knochel reagents) are found to be active in the cross-coupling reaction with allenic bromides affording acetylenic products with a high regio and stereoselective 1,3- anti substitution. The coupling process, which has been successfully extended to functionalized cuprates, can also be performed with alkylzinc chlorides in the presence of catalytic amounts of cuprous salts.

Morphology of nanocomposites from ethylene-acrylic acid copolymers

Abstract New nanocomposites have been prepared by melt-compounding from commercial ethylene-acrylic acid copolymers (EAA) of different molar mass, molecular structure (branched or linear) and AA concentration, and a Zn-ionomer, with three commercial clays containing different proportions of the same organic modifier (dimethyldi(hydrogenated tallow)ammonium ion). Their morphology has been preliminarily investigated by X-ray scattering and transmission electron microscopy. The nanocomposites showed disordered intercalated morphology, with an expansion of the average gallery height, which appears to depend quite strongly on the molecular architecture of the EAA, whereas the other investigated variables, including the excess of surfactant used to organically modify the silicate, have negligible effect.

Structural transitions and physical networks in wax-modified bitumens

This research focuses on the characterisation and evaluation of wax-modified bitumens for use in warm mix asphalt (WMA). Wax-modified bitumens were produced by addition of different types of wax to a 50/70 unmodified bitumen. Five different waxes were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-functionalised waxes. A basic structural picture of wax-modified bitumens was initially derived from the analysis of the thermal properties and morphological arrangements. The mechanical properties of the binders were then evaluated by rheometry, which indicated that bitumen modification with synthetic and functionalised waxes provides significant alteration in the overall colloidal structure. A comprehensive analysis of linear viscoelastic spectra depicted the existence of a sequence of structural transitions and relative behavioural processes, which deeply alter the behaviour of the original binder at in-service temperatures. All the rheological dynamics were interpreted in the light of the concept of residual crystallinity. The presence of physical networks generated by contiguous microcrystalline segments was finally hypothesised to explain the gel-like behaviour of the materials.

Kerosene-Resistant Asphalt Binders Based on Nonconventional Modification

The development of bituminous binders with an intrinsic fuel resistance is required to limit pavement damage and maintenance operations in those areas, such as airport systems and industrial areas and filling stations, where the risk of fuel spilling exists. This paper focuses on the study of the interactions between bitumen and fuel to attain a composition of modified binders with enhanced fuel resistance. Several different modifiers, including polymeric materials, recycled crumb rubber, and synthetic waxes, were added to a base bitumen. All blends were studied with special reference to their chemical composition and subjected to a solubility test consisting of a controlled immersion in kerosene (jet fuel A-1). The results were interpreted on the basis of the compositional characteristics which determine the interactions occurring between bitumen and modifiers. Among the formulations with enhanced fuel resistance, those based on synthetic waxes appeared to be the most interesting ones.

Synthesis of GAP and PAMMO Homopolymers from Mesylate Polymeric Precursors

In azidic binders for solid propellants, the N3 functionality is introduced by substitution of a halogen or tosyl group, but recently the mesyl group has been suggested as an alternative. The mesylate group has two advantages, mainly related to its small dimensions and low cost. Poly(glycidyl azide) and poly 3-azidomethyl-3-methyl oxetane were prepared by using both tosylate and mesylate precursors. The azidation kinetics were studied at three different temperatures while keeping all other operating parameters the same. The results confirmed the good potential of the mesylate precursors for the production of azidic binders.