Environment materials characterization

The large-scale spread of DAFCs is closely related to the development of efficient anodic and cathodic materials, characterized by very fast electrochemical kinetics, stability at the high current densities in alkaline environments and modest cost. This objective requires cathodes without noble metals and anodes with very low amounts of noble metals. In order to improve the cheapness and sustainability of the processes described above, the most accepted opinion is the possibility of using solar light by means of the introduction of Ti02, pure or doped, into the electrode material formulation. Figure 4.15 shows a typical laboratory-scale photoelectrocatalytic reactor. 

A large diffusion may be found also for composite materials, carbon, or metal based. In the first case different types of polymeric resins (thermoplastics, such as polypropylene, polyethylene, and PVDF, or thermosettings, such as epoxies and phenolics) are filled with carbonaceous powders (graphite or carbon blacks), to provide a material characterized by very high chemical stability in the fuel cell environment and satisfactory properties of electrical conductivity, but which cannot offer sufficient robustness at thickness lower than 2 mm. The metal composite plates are essentially based on combinations (sandwiches of different layers) of stainless steel, porous graphite, and polycarbonates, with the aim to exploit the characteristics of different materials. Their fabrication can be more complex but this is compensated by the possibility to incorporate other functional components, such as manifolds, seals, and cooling layers. 

Traditionally, new material characterization is performed ex situ using techniques that require environments which distort the properties of the material under consideration. Consequently, they are of little use in characterizing dynamic structures. Most spectroscopic techniques, for example, are used in air or in a vacuum. For dynamic polymer systems that are used in solution, such methods do not provide all essential information. In addition, conventional techniques do not normally allow the imposition of stimuli capable of collecting information on the molecular changes brought about by these stimuli in real time. 

The investigation of the compatibilization and crystallization of blends of polyolefins with a semiflexible LCP leads to the following conclusions the compatibilization of polyolefin/LCP blends has been realized successfully by the addition of ad hoc synthesized polyolefin-g-LCP copolymers. The compatibilization results into materials, characterized by a stabilized morphology, improved crystallization kinetics under nonisothermal and isothermal conditions, and enhanced mechanical properties. Moreover, polyolefin processability has been enhanced by the addition of LCP, even in the presence of compatibilizers. New high quality materials with improved processability have been produced by technologies, which are economic, friendly to the environment, and socially acceptable. 

The project was coordinated by the Studio di Ingegneria Ambientale (Milano, Italy). The preparation of the sediment reference material was carried out by Ecoconsult (Gavirate, Italy) and the Environment Institute of the EC Joint Research Centre of Ispra (Italy). The homogeneity and stability were verified at two laboratories from the Presidio Multizonale di Prevenzione (La Spezia and Venice, Italy). The material characterization (with regard to bacterial flora) was performed at the University of Siena (Italy). 

Although construction and operation of nuclear power plants are closely monitored and regulated by the NRC, an accident, though unlikely, is possible. The potential danger from an accident at a nuclear power plant is exposure to radiation. This exposure could come from the release of radioactive material from the plant into the environment, usually characterized by a plume (cloud-like) formation. The area the radioactive relea.se may affect is determined by the amount released from the plant, wind direction and speed and weather conditions (i.e., rain, snow, etc.) which would quickly drive the radioactive material to the ground, hence causing increased deposition of radionuclides. 

We may think that corrosion problems are exclusive to metallic materials, or at least to materials characterized by electronic conductivity, and this is probably true as regards electrochemical corrosion. However, for example, rubber is subject to SCC in environments containing ozone, polystyrene is subject to SCC in environments containing aliphatic hydrocarbons, high-density polyethylene may be subject to SCC (e.g., in benzene), and ice is subject to cracking in environments containing alcohol. 

The purpose of this chapter is to describe an analytical tool which, when coupled with accelerated material characterization, is capable of predicting the long term durability of reinforced plastics for applications in hostile environments. Throughout the chapter, the words resin and polymer are used interchangeably, and the resin can be thermoplastic or thermosetting, but it must be remembered that thermosetting resins are much less prone to creep and other viscoelastic effects than are thermoplastics. 

Materials which are affected by environment are characterized by high crack growth rate. The effect of environment is generally to enhance crack growth rates. 

In the framework of LFR and ADS, alternative corrosion mitigation methods are investigated as well. The alternatives are the use of steels with a relatively high Si or A1 content. Both these elements have an impact on the oxide scale in terms of composition and/or growth rate. Further options are the coating or surface alloying of, for instance, Fe-Al or FeCrAlY on the steel surface. AU these methods show an improvement of the materials behavior, however for their full application in the reactor environment a characterization and validation program needs to be performed. 

Of great interest to physical chemists and chemical physicists are the broadening mechanisms of Raman lines in the condensed phase. Characterization of tliese mechanisms provides infomiation about the microscopic dynamical behaviour of material. The line broadening is due to the interaction between the Raman active chromophore and its environment. 

Trace Evidence. Trace evidence (23) refers to minute, sometimes microscopic material found during the examination of a crime scene or a victim s or suspect s clothing (see Trace AND residue analysis). Trace evidence often helps poHce investigators (24) develop connections between suspect and victim and the crime scene. The theory behind trace evidence was first articulated by a French forensic scientist the Locard Exchange Principle notes that it is not possible to enter a location, such as a room, without changing the environment. An individual brings trace materials into the area and takes trace materials away. The challenge to the forensic scientist is to locate, collect, preserve, and characterize the trace evidence. 

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