Search results for "thermal analysi"
showing 10 items of 212 documents
Novel epoxy formulations for high energy radiation curable composites
2005
Abstract It has been widely recognised that high energy radiation can be effectively applied to the cure of epoxy resins in applications as composite matrices or structural adhesives with improvements in product quality and/or reduction in production costs. In the presence of suitable initiators, polymerisation of epoxies occurs via cationic mechanism, thus restricting the choice of the resin system components to species which do not contain electron donor groups. The present investigation is aimed to identify suitable co-monomers to be formulated with an epoxy resin, resulting in different cure reaction kinetics and application properties of the cured resin. In particular, four different a…
Structural investigation of e-beam cured epoxy resins through solid state NMR
2012
Abstract In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artef…
Radiation curing of carbon fibre composites
2014
Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides…
Study of the thermal decomposition of bromazepan complexes with Co(II), Ni(II), Cu(II) and Zn(II)
1984
Abstract The thermal behaviour of complexes of bromazepan with Co(II), Ni(II), Cu(II) and Zn(II) was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The complexes decompose in two steps: dehydration and decomposition. A correlation between the dehydration temperatures of MB2Xn and the coordinating ability of X is observed.
Advances in Anodic Alumina Membranes-based fuel cell: CsH2PO4 pore-filler as proton conductor at room temperature
2009
Abstract Anodic alumina membranes (AAM) filled with cesium hydrogen phosphate proton conductor have been tested as inorganic composite electrolyte for hydrogen–oxygen thin film (≤50 μm) fuel cell (TFFC) working at low temperatures (25 °C), low humidity ( T gas = 25 °C) and low Pt loading (1 mg cm −2 ). Single module TFFC delivering a peak power of around 15–27 mW cm −2 , with open circuit voltage (OCV) of about 0.9 V and short circuit current density in the range 80–160 mA cm −2 have been fabricated. At variance with pure solid acid electrolytes showing reproducibility problems due to the scarce mechanical resistance, the presence of porous alumina support allowed to replicate similar fuel…
Thermal and spectroscopic investigation of europium and samarium sulphates hydrates by TG-FTIR and ICP-MS techniques.
2005
The investigation of europium(III) sulphate hydrate and samarium(III) sulphate hydrate was performed by thermal analysis (TG-DTG) and simultaneous infrared evolved gas analysis-Fourier transformed infrared (EGA-FTIR) spectroscopy. The TG, DTG and DTA curves were recorded at the 25-1400 degrees C in the dynamic air atmosphere by TG/DTA analyser. The infrared evolved gas analysis was obtained on the FTIR spectrometer. Eu(2)(SO(4))(3).nH(2)O (n=3.97) and Sm(2)(SO(4))(3).nH(2)O (n=8.11) were analysed, the dehydration and decomposition steps were investigated and the water content was calculated. The formation of different oxysulphates was studied. The trace rare earth elements in Eu and Sm sulp…
Simplified thermal analysis of naturally ventilated dwellings
1991
Abstract A simplified comprehensive methodology for thermal comfort prediction in a naturally crossventilated room is described. The methodology mainly consists of the following three steps: • - analysis of the dynamic thermal behaviour of the given room, by means of the admittance procedure; • - evaluation of the air flows rates and their velocities in the room, by means of a new simplified method; • - thermal comfort prediction by means of the Fanger's theory. The results obtained appear satisfactory and the simplified methodology makes itself a useful tool for the identification of appropriate choices at the early stages of the design process, regarding naturally ventilated buildings. Th…
Mode I fracture toughness behaviour of epoxy resincarbon fiber composites cured by ionising radiation
2012
In this work Mode I fracture toughness behavior of Electron Beam cured unidirectional CFRP laminates is investigated by means of standardized Double Cantilever Beam (DCB) tests. A matrix system, comprising a DGEBA epoxy monomer and a typical initiator of cationic polymerization, was used and panel samples assembled by hand lay-up. Curing was achieved by 20 to 40 minutes irradiation on a pulsed 10 MeV Electron Beam accelerator. One batch of resin was also mixed with 10 phr of a PES thermoplastic monomer in order to enhance the matrix toughness. The influence of fibre-matrix adhesion, matrix toughening and matrix crosslinking density on the mode I delamination behavior have been investigated …
Characterization of serpottas' stuccos by means of simultaneous thermal analysis: Preliminary results
2015
In this paper the Simultaneous Thermal Analysis (STA), i.e. thermogravimetric and differential thermal analysis, was used as a diagnostic tool to better understand the matter composition of some very valuable artworks the Serpottas’ stuccoes in Palermo. Particularly the STA was used in order to exclude the presence of an unusual calcium-bearing magnesium carbonate, and the thermal data were also used to quantify the magnesite to calcite ratio. The latter was investigated in order to evaluate the amount of magnesium in the lime used as binder as during 17th and 18th century in Sicily magnesium rich lime was indicated as the most valuable binder probably because this kind of lime has a higher…