Search results for "carbon"
showing 10 items of 6057 documents
Preparazione e caratterizzazione di nanocompositi strutturali costituiti da poliammide e carbonio nanostrutturato
2014
L’obiettivo della presente tesi di dottorato è stato la preparazione e la caratterizzazione di nanocompositi a matrice polimerica contenenti forme allotropiche del carbonio nanostrutturato; tali materiali, grazie alle particolari caratteristiche meccaniche e di rinforzo, trovano applicazione nella fabbricazione di speciali dispositivi individuali come guanti, elmetti, corpetti, etc... Sono state preparate fibre di poliammide (PA) contenenti carbon black (CB), nanoplacchette di grafite (GNP) e nanotubi di carbonio (CNT); per questi ultimi sono stati valutati, inoltre, gli effetti delle loro dimensioni e della funzionalizzazione della loro superficie sulle proprietà di rinforzo dei nanocompos…
Acid-Labile Surfactants Based on Poly(ethylene glycol), Carbon Dioxide and Propylene Oxide: Miniemulsion Polymerization and Degradation Studies
2017
Partially degradable, nonionic AB and ABA type di- and triblock copolymers based on poly(propylene carbonate) and poly(ethylene glycol) blocks were synthesized via immortal copolymerization of carbon dioxide and propylene oxide, using mPEG or PEG as a macroinitiator, and (R,R)-(salcy)-CoOBzF5 as a catalyst in a solvent-free one-pot procedure. The amphiphilic surfactants were prepared with molecular weights (Mn) between 2800 and 10,000 g·mol−1 with narrow molecular weight distributions (1.03–1.09). The copolymers were characterized using 1H-, 13C- and DOSY-NMR spectroscopy and size exclusion chromatography (SEC). Surface-active properties were determined by surface tension measurements (crit…
Identification of Polycyclic Aromatic Hydrocarbons (PAHs) in the black crusts of Sicilian stone monuments: distribution and sources
2004
Polycyclic Aromatic Hydrocarbons are a family of compounds with known carcinogenic potential; their properties of lipophilicity, low water solubility and adsorption to particles and sediments make them a potentially dangerous group of chemicals and a threat to the environment and its bio-resources. The concentrations of total Polycyclic Aromatic Hydrocarbons (PAHs) and 19 individual compounds in 8 black crusts sampled from historical building of Palermo (Italy) were analyzed, by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode. PAH concentrations ranged from 78 to 9798 g/Kg of dry matrix. The resulting distributions and molecular ratios of specific compo…
Potential of the polychaete Sabella spallanzanii as bioindicator for PHAs
2009
Every year 230.000 t of polycyclic aromatic hydrocarbons (PHAs) enter the marine environment, resulting ubiquitously distributed world‐wide. These compounds are aromatic molecules of special concern because of their toxic and carcinogenic properties. The two main sources of PHAs in the environment are fossil fuels, mainly crude oil, and the incomplete combustion of organic materials such as wood, coal and oil. They enter the sea by both atmospheric and aquatic routes. As a consequence of their hydrophobic nature, in aquatic environments PHAs rapidly tend to associate with particulate matter and sediments represent the most important reservoir. Animal and aquatic plants can accumulate PHAs f…
Experimental and theoretical studies on corals. I. Toward understanding the origin of color in precious red corals from Raman and IR spectroscopies a…
2010
An attempt to explain the origin of the vivid red color in precious pink and red corals was undertaken. Raman and IR spectroscopies were applied to characterize white, pink and red corals. The position of the Raman signal near 1500 cm−1 of some corals and pearls was associated by several authors with the presence of the mixture of all‐trans‐polyenic pigments, containing 6–16 conjugated CC bonds or β‐carotenoids. This hypothesis was examined theoretically by performing extensive B3LYP‐DFT calculations of vibrational spectra of the model polyenic compounds. The B3LYP/6‐311++G** predicted positions of the dominating Raman mode depend on the number of CC units (Cn parameter) and can be accura…
Raman Investigations to Identify Corallium rubrum in Iron Age Jewelry and Ornaments
2016
International audience; During the Central European Iron Age, more specifically between 600 and 100 BC, red precious corals (Corallium rubrum) became very popular in many regions, often associated with the so-called (early) Celts. Red corals are ideally suited to investigate several key questions of Iron Age research, like trade patterns or social and economic structures. While it is fairly easy to distinguish modern C. rubrum from bone, ivory or shells, archaeologists are confronted with ancient, hence altered, artifacts. Due to ageing processes, archaeological corals lose their intensive red color and shiny surface and can easily be confused with these other light colored materials. We pr…
Comparative Investigation on the Soil Burial Degradation Behaviour of Polymer Films for Agriculture before and after Photo-Oxidation
2020
Polymer films based on biodegradable polymers, polyethylene (PE) and modified PE with oxo-degradable additive were prepared by film blowing. Carbon black (1%) was added to all the films. Commercial biodegradable Ecovio®
Photo-oxidation behaviour of composite polyethylene/MW-CNTs films
2008
PROCESSING AND CHARACTERIZATION OF THE POLYMER/CNTs NANCOMPOSITE FIBRES.
2009
Block copolymers from ionic liquids for the preparation of thin carbonaceous shells
2017
This paper describes the controlled radical polymerization of an ionic-liquid monomer by RAFT polymerization. This allows the control over the molecular weight of ionic liquid blocks in the range of 8000 and 22000 and of the block-copolymer synthesis. In this work we focus on block copolymers with an anchor block. They can be used to control the formation of TiO2 nanoparticles, which are functionalized thereafter with a block of ionic-liquid polymer. Pyrolysis of these polymer functionalized inorganic nanoparticles leads to TiO2 nanoparticles coated with a thin carbonaceous shell. Such materials may, e.g., be interesting as battery materials.