Franco Sandrolini

New polymer mortars containing polymeric wastes. Part 1. Microstructure and mechanical properties

Abstract Recycling industrial wastes as filler components and/or aggregates in polymer mortars makes these materials very interesting from an ecological and safety point of view. In addition, the resulting materials have useful physical and mechanical properties. Four recycled fillers (powdered rubbers, tyre rubbers, micronized tyre fibers and milled electrical cable wastes) have been used to formulate new polymer mortars. The comparison of their mechanical properties and microstructures with those of a plain polymer mortar indicates that the presence of recycled waste affects the physical–mechanical behavior (compressive and flexural strengths, microstructure). The use of silane coupling agents has been also considered and its effect in leading to more compact materials is reported and discussed.

Waste wash water recycling in ready-mixed concrete plants

Abstract Production of large amounts of waste wash water coming from ready-mixed concrete plants leads to problems of environmental impact. National laws usually prohibit the disposal of such types of water, due to their extremely high pH value and suspended matter amount, and require the water to be treated prior to discharge. prEN 1008 provides for recycling waste water in the production of new concrete, but gives some restrictions for its composition and use. In this paper, the use of waste wash water (coming from a medium-size ready-mixed concrete plant) in mixing water for concrete and mortars has been investigated: the effects on physical–mechanical properties and microstructure are investigated as a function of the characteristics of waste water used. The results have shown that mortar and concrete prepared with recycled water exhibit 28-day mechanical strength in no way lower than 96% of the reference materials (90% is the minimum allowed in prEN 1008) and, in some cases, even better. Moreover, the use of wash water in concrete leads to a reduction of the concrete capillary water absorption and mortar microporosity, which surely improves the durability of the material. This effect can be ascribed to the filling action of the fines present in the wash water and to the slight reduction of the actual water/cement ratio.

STRUCTURAL AND ELECTRICAL CHARACTERIZATION OF POLYMERIC HALOPLUMBATE(II) SYSTEMS

The synthesis and the structural, thermal, and electrical characterization of haloplumbate(II) systems are described. The counterions are diprotonated linear aliphatic amines, such as the 2-methylpentane-1,5-diamine (2meptH2) and propane-1,3-diamine (pnH2) dications. The (2meptH2)[PbCl4] and (2meptH2)[PbBr4] are isostructural, space group Cc, with a = 24.140(4) A, b = 7.720(2) A, c = 7.795(2) A, β = 98.1(1)°, Z = 4 for the chlorine compound and a = 24.539(4) A, b = 8.031(2) A, c = 8.198(2) A, β = 99.6(1)°, Z = 4 for the bromine compound; the (2meptH2)[Pb1.5I5] crystallizes in the triclinic P1 space group, with a = 11.803(3) A, b = 12.565(3) A, c = 8.494(8) A, α = 106.2(1)°, β = 100.5(1)°, γ = 117.4(1)°, Z = 2; the crystals of (pnH2)[PbCl4] are orthorhombic, space group P212121, a = 19.247(4) A, b = 7.862(2) A, c = 7.581(2) A, Z = 4; the (pnH2)2[Pb1.5Br7]·H2O crystallizes in the triclinic P1 space group, with a = 11.517(3) A, b = 14.122(3) A, c = 8.149(2) A, α = 104.1(1)°, β = 109.8(1)°, γ = 77.5(1)°, Z ...

A contribution to the study of aging of XLPE insulated cables

The electrical, thermal, and multiple-stress (thermal and electrical) aging of cross-linked polyethylene (XLPE) cable models has been investigated in order to get information on aging effects and mechanisms. After endurance tests, XLPE cable models have been subjected to chemical, physical, electrical, and microstructural characterization. Thermal aging results reveal that bulk degradation occurs in the cables at temperatures higher than the melting point. Multiple-stress aging data emphasize a synergistic effect of electric field and temperature. Significant microstructural changes detected in the cables aged under multiple stress are evidence of this effect and can partly explain the time behavior of the electric strength. >

ORGANIC/INORGANIC COMPOSITE MATERIALS : SYNTHESIS AND PROPERTIES OF ONE-DIMENSIONAL POLYMERIC HALOPLUMBATE(II) SYSTEMS

Abstract In this paper we report the synthesis and the thermal, spectroscopic and electrical characterization of 1-D polymeric haloplumbates(II) of formula (A) [PbX3] (A = piperidinium] (pdH), morpholinium (mpH) cation; X = Br, I for pdH and Cl, Br for mpH). For the morpholinium compounds we report also the structural analysis. The (mpH) [PbX3] (X = Cl, Br) complexes are isomorphous and crystallized space group P212121. The unit cell dimensions are a = 15.249(3), b = 8.001(2), c = 7.625(2) A , V = 930.3(4) A 3 , Z = 4 for (mpH) [PbCl3] and a = 15.760(3), b = 8.254(2), c = 7.866(6) A , V = 1023.2(4) A 3 , Z = 4 for (mpH) [PbBr3]. The final R value is 0.0428 (Rw = 0.0442) for (mpH) [PbCl3] and 0.0434 (Rw = 0.0453) for (mpH) [PbBr3]. The structure consists of morpholinium cations and infinite polymeric anions [PbX3−]n; each lead atoms is surrounded by six halogen atoms forming a strongly distorted octahedronl adjacent octahedra share faces to form 1-D endless chains in which two consecutive lead atoms are bridged by three halogen atoms. The distortion in the (PbX6) octahedra of (mpH) [PbX3] enables the metal ion to be involved in a semicoordinative bond with the oxygen atom of the morpholinium cation, which makes the lead(II) coordination 6 + 1. All the structures are tridimensionally built up by a network of intermolecular NH⋯X bonds.

Electrical properties of nickel hydroxide for alkaline cell systems

Abstract The electrical behaviour of nickel hydroxide/oxyhydroxide electrodes for advanced alkaline cell systems is investigated as a funciton of oxidation degree which usually changes during practical operation of these systems. The d.c. electrical conductivity, relative dielectric constant and loss factor as a function of oxidation degree, temperature and frequency (a.c. properties) are investigated and discussed. Moreover, the effect of water absorption on the electrical conductivity is investigated. An insulating behaviour and ionic mechanism of conduction is pointed out for the uncycled and reduced electrodes, while the oxidized electrode behaves essentially as a semiconductor. Water absorption causes a strong increase in the electrical conductivity of the uncycled and reduced electrodes. Cycling enhances the dielectric losses of the active material.

A study of pseudo 1-D copper(I) halide systems exhibiting anomalous copper(II) character: physical characterization of (paraquat) Cu2X4 (X = Cl, Br, I)

The salts (paraquat)Cu2X4 (X = Cl, Br, I) have been synthesized and their crystal structure determined. The chloride salts is tetragonal, space group P42/n, a = 16.352(2), c = 5.911(2) A, V = 1580.7(6) A3, Dx = 1.87 g cm−3, Z = 4 and R = 0.0546. The bromide analog is monoclinic, space group P21/n, a = 8.715(6), b = 11.103(6), c = 13.386(7) A, β = 98.02(4)°, V = 1666(1) A3, Dx = 2.52 g cm−3, Z = 4 and R = 0.0680. The iodide salt is tetragonal, space group P42212, a = 12.416(2), c = 6.544(3) A, V = 1008.8(5) A3, Dx = 2.70 g cm−3, Z = 2 and R = 0.0995. Infinite chains of distorted, edge sharing, Cu(I)X43 tetrahedra are common to all three structures. The bond distances and angles about the copper centers are consistent with known Cu(I)X43 species. The paraquat catrons form stacks parallel to the chain axis, and all three structures show weak N⋯X and C⋯X contacts. The chloride and iodide salts are nearly isostructural, and differential scanning calorimetry shows a phase transition in the chloride salt at 188°C. The iodide salt is a pure copper(I) system. A temperature dependent magnetic susceptibility experiment shows the bromide salt to contain a 2% Cu2Br62− impurity. Two chloride compounds showing the same structure have been synthesized. One of these salts has 1% copper(II) character, while the other has 10% copper(II) character. EPR shows the 1% character to be a CuCl2·2H2O impurity. Magnetic susceptibility, EPR, powder diffraction and electrical conductivity results show that the 10% copper(II) character is incorporated into the [CuCl2], chain structure, with an accompanying vacancy. Preliminary conductivity measurements show that the Cl and I salts are insulators, but hint at enhanced conductivity for the bromide analog.

New polymer mortars containing polymeric wastes. Part 2. Dynamic mechanical and dielectric behaviour

Abstract A promising application for polymer mortars and concretes is for machine tool structures: for this purpose, composite materials with good mechanical properties and high damping characteristics are required. Accordingly, four recycled fillers (powdered rubber, tyre rubber, micronized tyre fibres and milled electrical cable waste) have been used to formulate new polymer mortars. The internal energy dissipation and relaxation processes of the different materials, studied by the combined use of both dynamic mechanical and dielectric analysis, are compared thus showing the effect of the powdered rubber based filler as a damping promoter. The use of silane coupling agents has also been investigated and its effect in leading to stiffer materials is reported and discussed.

Matt waste from glass separated collection: An eco-sustainable addition for new building materials

Matt waste (MW), a by-product of purification processes of cullet derived from separated glass waste collection, has been studied as filler for self-compacting concrete and as an addition for newly blended cement. Properties of self-compacting concrete compared to reference samples are reported. They include characteristics at the fresh and hardened states, and the compressive strength and porosity of mortar samples that were formulated with increasing amounts of MW to be used as cement replacement (up to 50wt.%). The effects of matt waste are discussed with respect to the mechanical and microstructural characteristics of the resulting new materials.

Structural studies and electrical properties of recycled glasses from glass and incinerator wastes

The electrical behaviour of different glass compositions obtained from mixing waste glass deriving from a community glass recycling program and silicate waste from the incineration of municipal solid residues (from Reggio Emilia city) have been investigated as a function of temperature and frequency. The electrical and dielectric properties were related to structural studies performed on the same glassy materials. As the amount of incinerator wastes increases, on account of lower alkali and higher alkaline-earth content in the final glass composition, conductivity and dielectric losses decrease approaching the behaviour of type E glass fibres, so envisaging a possible use of waste-containing glasses in the production of high voltage insulators.