Andrea Saccani

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.

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 ...

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.

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.

Improving thermal endurance properties of polypropylene by nanostructuration

Isothermal thermogravimetric analysis is used as analytical technique for short-term thermal endurance characterization of nanostructured isotactic polypropylene. The nanofiller consists of organophilic-modified fluorohectorite, that is, a layered silicate. It is shown that the temperature index improves considerably with respect to the base polypropylene, with only 6 wt.% of nanofiller, thus enabling the potential use of the thermoplastic nanostructured material at significantly higher operating temperatures.

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.

SYNTHESIS, THERMAL AND ELECTRICAL CHARACTERIZATION OF 2-METHYLPENTANE-1,5-DIAMMONIUM TETRACHLOROCADMATE(II) WITH PEROVSKITE-LIKE STRUCTURE

Abstract This paper repotts the synthesis and the structural, thermal and electrical characterization of the 2-methyl-pentane-1,5-diammonium bidimensional chlorocadmate(II) system with perovskite-like structure. Its structure consists of layers of CdCl6 corner-sharing octahedra extending in the ab plane. Interposed sheets of organic dications link adjacent layers through hydrogen bonding and contribute to the crystal packing. The presence of a methyl group on the C(4) atom of the organic chain is considered responsible for the thermal stability of the compound between room and melting temperature (605 K). The compound behaves as an electrical insulator at low temperature approaching semiconducting values at higher temperature. These results are also compared with those found for other structurally similar compounds.

Thermal endurance evaluation of poly(butylene terephthalate) by conventional and analytical methods

The thermal endurance of poly(butylene terephthalate) was evaluated by both consolidated long-term conventional life tests and a short-term analytical procedure. The latter is based on oxidative stability measurements by isothermal differential calorimetry in a pure oxygen flow. The capability of the analytical technique to provide an activation energy for the thermo-oxidation process was verified. The results obtained by the two methods were compared and discussed. It is shown that the temperature index derived by the analytical procedure can be close to that obtained by the conventional tests, provided that a suitable selection of the test temperatures and failure criteria is made; however, benefits in term of test time shortening are lower than those previously obtained for polyolefin-based materials.