1,721,234 research outputs found
Overview of the rheological behaviour of ceramic slurries
No full textGiven that the majority of raw materials used in the ceramic industry have sedimentary origins, their formation is conducted in aqueous medium, reason for which most ceramic production processes involve water for manufacturing diverse semi-finished materials. However, the rheological behaviour inherent of ceramics may infer significant impact on their processing, defining crucial parameters such as solid-to-water ratio, deflocculation level, and tpye and amount of chemical additives to be used. Thus, the present work explores the intricacy of essential aspects of rheology in ceramic slurries, intending to provide an overview of the chemical, physical and practical influence on the manufacturing of tiles from both industrial and scientific points of view
PLANT FOR DISPOSING OF USED TYRES
No full textA plant (1) for transforming into secondary raw material, or disposing of, used tyres (P), made of rubber or other carbon matrices, comprises at least one pyrolysis chamber (6), wherein said used tyres (P) are subjected to pyrolysis treatment, said tyres (P) being conveyed to said at least one pyrolysis chamber (6) by means of at least one supplying device (5) that receives the tyres (P) from a first conveying device (3), at least one hydraulic seal element (9) associated with said at least one supplying device (5) and heating means (16) for heating said at least one pyrolysis chamber (6). The at least one supplying device (5) comprises a second conveying device (7) that receives the tyres (P) from the first conveying device (3) and conveys the tyres (P) through said at least one hydraulic seal element (9) and along at least one supplying conduit (11) that extends prevalently vertically until it reaches an inlet zone (12) of the at least one pyrolysis chamber (6), where said tyres (P) are released by said second conveying device (7) and drop by gravity into said pyrolysis chamber (6) through an inlet opening (13). The inlet opening (13) is provided with a movable closing element (14), that can rotate around a hinge element (16) between a closed position and an open position and an end portion (15) of the at least one supplying conduit (11), in contact with the at least one pyrolysis chamber (6), is made of thermally insulating material. The movable closing element (14) and the end portion (15) in thermally insulating material minimise the transmission of heat to the hydraulic seal element. Below an openable bottom (28) of the pyrolysis chamber (6) a hopper (22) is arranged that is suitable for conveying solid residual materials of the pyrolysis treatment to a shredding device (23), said hopper (22) being provided with pushing means (32) arranged for pushing to the shredding device (23) solid residues that accumulate on the walls of the hopper (22)
PLANT FOR DISPOSING OF USED TYRES
No full textA plant (1) for transforming into secondary raw material, or disposing of, used tyres (P), made of rubber or other carbon matrices, comprises at least one pyrolysis chamber (6), wherein said used tyres (P) are subjected to pyrolysis treatment, said tyres (P) being conveyed to said at least one pyrolysis chamber (6) by means of at least one supplying device (5) that receives the tyres (P) from a first conveying device (3), at least one hydraulic seal element (9) associated with said at least one supplying device (5) and heating means (16) for heating said at least one pyrolysis chamber (6). The at least one supplying device (5) comprises a second conveying device (7) that receives the tyres (P) from the first conveying device (3) and conveys the tyres (P) through said at least one hydraulic seal element (9) and along at least one supplying conduit (11) that extends prevalently vertically until it reaches an inlet zone (12) of the at least one pyrolysis chamber (6), where said tyres (P) are released by said second conveying device (7) and drop by gravity into said pyrolysis chamber (6) through an inlet opening (13). The inlet opening (13) is provided with a movable closing element (14), that can rotate around a hinge element (16) between a closed position and an open position and an end portion (15) of the at least one supplying conduit (11), in contact with the at least one pyrolysis chamber (6), is made of thermally insulating material. The movable closing element (14) and the end portion (15) in thermally insulating material minimise the transmission of heat to the hydraulic seal element. Below an openable bottom (28) of the pyrolysis chamber (6) a hopper (22) is arranged that is suitable for conveying solid residual materials of the pyrolysis treatment to a shredding device (23), said hopper (22) being provided with pushing means (32) arranged for pushing to the shredding device (23) solid residues that accumulate on the walls of the hopper (22)
Straightforward synthesis of well-defined poly(vinyl acetate) and its block copolymers by atom transfer radical polymerization
No full textA facile Atom Transfer Radical Polymerization (ATRP) method based on the use of the complex obtained with CuCl, CuCl2 and the very active ligand 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Me6CyClam) as catalytic system, was successfully employed for the first time to polymerize vinyl acetate (VAc) with a good control over the polymerization, which showed a living character and monomer conversion up to 90%. The use of such an active ligand allows to maintain a particularly low concentration of propagating species once very reactive radicals, from such monomers, are formed, hence establishing a fast and dynamic ATRP equilibrium. Several kinetic studies on the ATRP of VAc were carried out with the aim to identify the optimized conditions allowing a good control over the process attaining materials with well-defined structure and low polydispersity. The livingness of the macromolecular system was confirmed, among the others, by using the obtained PVAc as ATRP macroinitiator for the synthesis of several block copolymers. Furthermore, the possibility to hydrolyse the VAc block thus attaining amphiphilic materials was studied
Morphology, thermal, mechanical properties and ageing of nylon 6,6/graphene nanofibers as Nano2 materials
Full text linkNylon 6,6 nanofibers loaded with different Graphene (G) amounts were successfully produced with stable process and good fiber quality, using an optimized solvent system suitable both for electrospinning and for G-suspension. G addition is found to significantly affect diameter but not thermal behaviour. A new phenomenological model is proposed for the interpretation of mechanical behaviour of nanofibrous mat, trying to take into account the nanofibrous morphology. The model highlights a G contribution to mechanical properties that mainly affects the initial steps of deformation where fibers stretch, slide, twist and re-orient. Finally, the nanofibers were analysed after 20 months ageing, showing no significant alteration with respect to the pristine ones, thus the lack of detrimental ageing-effects due to G addition
Installation and method for recovering carbon or glass fibres from composite materials
No full textL’invenzione riguarda un impianto e un metodo per il recupero di fibre di
carbonio o di vetro da materiali compositi nei quali dette fibre sono racchiuse in una
matrice polimerica.
suddetti materiali compositi possono provenire da scarti prodotti in diversi stadi
di lavorazione industriale e/o da manufatti giunti al termine del loro ciclo di vita
Quality assessment of carbon fiber automotive parts when using polyurethane foam as pattern material
No full textHigh density polyurethane foams have recently emerged in industry aiming to provide an innovative pattern material for the manufacture of fiber reinforced composite plastics. With the intent of understanding the constraints in the usage of such mold material for producing automotive carbon fiber parts, the present work enlightens a pre-treatment procedure to be considered including steps such as the application of sand papers, sealer, release agent and release paste wax taking into account even a study of the curing thermal cycle to produce quality parts with a negligible level of pitting taking into account the limitations inherent of the polyurethane that favor the presence of such defect
Chirality on Amorphous High-Tg Polymeric Nanofilms: Optical Activity Amplification by Thermal Annealing
No full textThe chiroptical properties of amorphous chiral polymers functionalized with conjugated trans-azoaromatic chromophore linked to the backbone through a chiral cyclic pyrrolidine moiety of one single configuration at the solid state, as thin films, were investigated. For the first time nanometric thin films of amorphous polymers (not liquid crystals) showed a remarkable chiral amplification upon thermal treatment at a temperature close to their Tg. The side-chain azobenzene chromophores rearrangement driven by the enhanced chain mobility seems to favor the formation of nanodomains of conformationally ordered macromolecular chains with one prevailing helical handedness whose optical activity depends on the configuration of the intrinsic chirality of the monomeric units and which as a result are stable at room temperature for a long time
Evaluation of Tryptophan - Late curing agent systems as hardener for epoxy resin
No full textIn order to obtain a low-toxic and environmentally friendly epoxy system, the novel green curing agent L-Triptophan was used, in combination with the two commercial late curing agents 2-Undecyl-1H-imidazole and 3,3'-(4-Methyl-1,3-phenylene)bis(1,1-dimethylurea), as hardener system for the cross-link of Diglycidyl Ether of Bisphenol A (DGEBA). The thermal behavior of the precursors mixtures was evaluated by dynamic and isothermal Differential Scanning Calorimetry (DSC) and confirmed L-Tryptophan as a possible novel green curing agent for DGEBA. These encouraging results pave the way for a further study of a new class of low-toxic and sustainable curing agent systems for the production of fully bio-based epoxy resins
Evaluation of antimony-free flame retardants for pPVC synthetic leathers intended for safer automotive interiors
No full textAntimony-based compounds have been the state-of-the-art flame retardants (FRs) for plasticized PVC (pPVC) due to their superior efficiency at very low loading. However, the use of antimony compounds poses more than an issue, for both human health and the environment, related to their extraction, processing and use. In order to follow the consequent need to phase out antimony compounds, different FRs for high-performance plasticized PVC (pPVC) synthetic leathers (SLs), intended for automotive interiors applications, have been selected amongst readily available on the market additives and tested in highly plasticized formulations. These FRs have been evaluated either alone or in combination in order to ascertain possible synergistic effects. The samples have been obtained with standard procedures used in the R&D laboratory of Vulcaflex S.p.A., and tested for thermal stability, mechanical and flame resistance, following standard and internal methods. Results have been then compared to those of a neat pPVC foil (DUP) and of a foil containing 2 phr of antimony trioxide (ATO). Amongst the alternatives tested, various combinations proved effective in improve flame retardancy without negatively affecting mechanical properties, and proving to be, thus, promising candidates to substitute ATO as FRs in pPVC materials
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