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The chemistry of caffeine
(2012)
Laminates of carbon fiber reinforced plastic (CFRP), which are manufactured by injection technology, are reinforced with boehmite particles. This doping strengthens the laminates, whose original properties are weaker than those of prepregs. Besides the shear strength, compression strength and the damage tolerance, the mode of action of the nanoparticles in resin and in CFRP is also analyzed. It thereby reveals that the hydroxyl groups and even more a taurine modification of the boehmites' surface alter the elementary polymer morphology. Consequently a new flow and reaction comportment, lower glass transition temperatures and shrinkage, as well as a changed mechanical behavior occur. Due to a structural upgrading of the matrix (higher shear stiffness, reduced residual stress), a better fiber-matrix adhesion, and differing crack paths, the boehmite nanoparticles move the degradation barrier of the material to higher loadings, thus resulting in considerably upgraded new CFRP.
Under environmental conditions water exists in all three classical States of matter: solid, liquid and gas. The water molecule is non-linear and therefore polar. In comparison with other liquids water has anomalous features; about 63 exceptional properties are recorded. This article starts with reviewing properties of water, typical occurrences and definitions such as relative and absolute humidity and moisture content.
Water is present everywhere in nature and engineering; it may be helpful or harmful. The survey concerns both: atmospheric hygrometry and usual measuring methods of the moisture content of solids and liquids as well as water Sorption. The determination of the atmospheric humidity is among the more difficult problems in metrology. In contrast, humidity determination of materials is simple; however the definition of the dry state is difficult. Because water is bound at and in solids and liquids in many different ways it tums out that the humidity content of materials is difficult to define and to measure accurately. We provide a survey on the measuring methods, describe the most important ones and discuss advantages and accuracy.
In the search for extraterrestrial water special remote measuring methods have been developed analysing the spectrum of electromagnetic radiation either of natural sources or produced by a probe and reflected. Spacious deposits have been detected photographically. In situ investigations are made using conventional methods.
With regard to the problems of measurements, Standardisation of measuring methods and procedures is required. There exist many institutions, which are engaged in investigating the use of water and standardising measuring methods. In tabular form, we give a survey on existing Standards.
Fractionation
(2012)
The enormous diversity of polymers with respect to molecular weight, molecular architecture, and – in the case of copolymers – also the content and arrangement of dissimilar monomers requires well-targeted methods for the separation of the different species that are contained in a given sample. This chapter presents the most abundant fractionation procedures, which are either based on thermodynamic driving forces (like in the case of liquid–liquid phase separation) or on kinetic effects (as with field-flow fractionation).
In order to reduce experimental effort, tribological tests are performed for coating selection, simulating the friction, wear and scuffing behaviour between the piston ring and cylinder liner, as well as lubricant evaluation. The creation of test standards in piston ring/cylinder liner simulation is discussed. PVD coatings, HVOF coatings and nitriding treatments have been applied to piston rings as alternative for chromium coatings. CrN/TiN coating seems very effective for increasing the wear and scuffing resistance. Biodegradable engine oils based on esters and polyglycols reduce friction and exceed the wear resistance of reference engine oils based on hydrocarbons for the new generation engines with high cylinder pressures.
In recent years mass spectrometric methods, in particular matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) time-of-flight (TOF) mass spectrometry (MS) have become indispensable tools for analyzing molecular masses and mass distributions of polymers. Moreover, these techniques offer the advantage of being able to determine simultaneously chemical functionality, and compositional and topological distributions of polymers. Especially in combination with liquid and/or gas phase separation methods, a comprehensive polymer characterization can be achieved and the difficulties of MS to analyze chemically heterogeneous polymers, copolymers, and samples with broad molecular mass distribution can be overcome.