Search results for "Roth"
showing 10 items of 806 documents
Ethylene-vinyl Acetate Thermoplastic Copolymers Filled with Multiwall Carbon Nanotubes: Effect of Hydrothermal Ageing on Mechanical, Thermal, and Ele…
2013
A range of properties of two commercial thermoplastic ethylene-vinyl acetate (EVA) copolymers, Elvax 420 and Elvax 450, neat and as melt-mixed composite filled with 15 wt.-% of multi-wall carbon nanotubes (MWCNTs), are studied in the “as produced” state and after hydrothermal ageing. Addition of MWCNTs into the neat copolymers introduces the functionality of electrical conductivity and significantly improves their mechanical properties, while thermal characteristics are slightly affected by the presence of carbon nanotubes. A remarkable increase of the elastic modulus (150%) and stress at failure (50%) in stress–strain experiments as well as creep resistance (40%) of the nanocomposites in c…
Chemical evolution of ore-forming brines – Basement leaching, metal provenance, and the redox link between barren and ore-bearing hydrothermal veins.…
2019
Abstract Six mineralogically exemplary barren and mineralized hydrothermal veins (with Pb and Zn ores) of Jurassic-Cretaceous and Cenozoic age in the Schwarzwald mining district, SW Germany were chosen to shed light on the origin of their mineralogical diversity. The selection of the veins was guided by the fact that they represent the largest number of veins in the region, are very well known mineralogically and geochemically, and they provide nice examples of barren and mineralized veins of similar age. Fluid inclusion data from the individual veins overlap implying their diverse mineralogy is not caused by different fluid compositions participating during fluid mixing. LA-ICPMS data of s…
Asymmetric Synthesis of Spiro Tetrahydrothiophene-indan-1,3-diones via a Squaramide-Catalyzed Sulfa-Michael/Aldol Domino Reaction
2016
Synthesis 48(08), 1131-1138(2016). doi:10.1055/s-0035-1560412
Environmental impact of mining activities on the Hermioni area, Greece
1993
Publisher Summary This chapter investigates the environmental impact of mining activities in the Hermioni area, Greece, including the offshore area. A chemical analysis of sediments associated with diabase lavas in the Hermioni mine area has shown significant enrichments in Fe, Mn, Zn, Cu, and As relative to normal pelagic clays. Marked geographic compositional variations within the Hermioni area have been observed, the highest metal enrichments found at Baroutospelia. Mineralogically the Fe–Mn sediments contain hematite, quartz, and minor amounts of illite, smectites, and feldspars. A chemical analysis of sulfide ore samples showed that the Hermioni ores are Cu-rich pyrites, always contain…
Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends. Thermal, mechanical and morphological behaviour
2011
Abstract A model epoxy resin/anhydride system, modified with a polyethersulfone (PES) engineering thermoplastic toughening agent, has been studied under hydrothermal ageing in order to investigate the modification of the thermal, morphological and mechanical behaviour through dynamical mechanical thermal analysis, SEM microscopy and fracture toughness test respectively. Two different concentrations of the toughening agent were used in the blends and two ageing conditions have been considered, consisting of the immersion of the samples in distilled water at constant temperature of 70 °C for 1 week and for 1 month. Dynamical mechanical thermal analysis results on hydrothermally aged materials…
Mode I fracture toughness behavior of hydro-thermally aged carbon fibre reinforced DGEBA-HHPA-PES systems
2012
In this work the Mode I fracture toughness behavior of unidirectional CFRP laminates is investigated by means of Double Cantilever Beam (DCB) tests. The composite samples were manufactured by thermal curing after impregnation of a Carbon fabric with a DGEBA epoxy and anhydride HHPA curing agent. One resin batch was also mixed with a PES thermoplastic monomer to enhance the matrix toughness. Two lots of samples, toughened and un-toughened, were then left to soak in hot water to achieve various degrees of aging. The influence of matrix toughening and hydrothermal aging on the delamination behavior of the composite have then been assessed and correlated with characterization data from Dynamic …
ChemInform Abstract: Continuous Hydrothermal Synthesis of Nanometric BaZrO3in Supercritical Water.
2008
Abstract Nanocrystalline barium zirconate (BaZrO 3 ) was synthesized using a hydrothermal synthesis process working in supercritical conditions and in a continuous way. By this method, we succeeded in the continuous and rapid production of nanopowders. As a preliminary work three barium precursors have been investigated: barium hydroxide (Ba(OH) 2 ), barium acetate (Ba(CH 3 COO) 2 ) and barium nitrate (Ba(NO 3 ) 2 ). Two of them (Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 ) led to the pure perovskite phase. Then an experimental design has been conducted in order to determine the influence of the experimental parameters on the crystallinity and the grain size of the final product.
Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxide catalysts
2004
Abstract MoVTeNbO catalysts, prepared by hydrothermal synthesis, are active and highly selective in the ODH of ethane, especially those with a MoVTeNb molar ratio of 1–0.15–0.16–0.17 and heat-treated at 600–650 °C. On the best catalyst, selectivities higher than 80% at ethane conversion levels higher than 80% have been obtained operating at relatively low reaction temperatures (340–400 °C). Thus, yields of ethylene of ca. 75% have been obtained, which exceeds the best yield reported in the literature. Te 2 M 20 O 57 ( M =Mo, V, Nb) and (V,Nb)-substituted θ -Mo 5 O 14 , in addition to small amounts of the Te 0.33 M O 3.33 ( M =Mo, V, Nb) phase, can be proposed in the most selective cataly…
Soft hydrothermal synthesis of new microporous materials based on phosphate-like species
1994
ABSTRACTFactors controlling hydrothermal synthetic procedures are not well understood. A good knowledge of the solution chemistry of precursor species is the best reference for the design of rational procedures. Examples of the predictive character of simple models in order to rationalize complex syntheses are discussed in detail.
Simple New Method for the Preparation of La(IO<sub>3</sub>)<sub>3</sub> Nanoparticles
2020
We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route which takes a matter of hours, thereby providing an alternative to the common hydrothermal method which takes days. Nanoparticles of pure &alpha;-La(IO3)3 and pure &delta;-La(IO3)3 were synthesised via the new method depending on the source of iodate ions, thereby demonstrating the versatility of the synthesis route. The crystal structure, nanoparticle size-dispersal and chemical composition were characterised via angle- and energy-dispersive powder X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectrosco…