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Pyrolysis, flammability, fire behavior, melt viscosity, and gas diffusion of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) were investigated, with bisphenol A bis(diphenyl phosphate) (BDP), with 10 wt.% talc and with BDP in combination with 5, 10 and 20 wt.% talc, respectively. Compared to PC/ABS, PC/ABS + BDP results in an increased decomposition temperature of PC, a higher char yield, a significantly increased LOI, a V-0 classification in UL 94, a reduced peak heat release rate (pHRR), and a reduced total heat release (THR) in the cone calorimeter. This efficient flame retardancy is due to mechanisms in both the gas and condensed phases. PC/ABS + 10 wt.% talc shows a decrease in the PC decomposition temperature. The fire behavior is improved in part compared to PC/ABS, with an increased LOI and reduced pHRR. PC/ABS + BDP + 10 wt.% talc shows a strong synergism in LOI, a V-0 classification, and a decrease in pHRR, whereas THR is slightly increased compared to PC/ABS + BDP. Talc decreases the gas diffusion and enhances the flow limit for low shear rates, both of which influence the pyrolysis and flammability results. Further, talc improves the protection properties of the fire residues. Nevertheless it also partly suppresses flame inhibition and the charring effect of BDP. The synergism between BDP and talc in LOI is obtained even for low talc loadings in PC/ABS + BDP + talc, whereas for higher loadings saturation is observed.
ICP-MS is based on the formation of (preferentially monovalent positively)charged atomic ions in an inductively coupled Ar plasma at almost 10 000 K. The ions formed are transferred from the plasma source at ambient pressure into a mass Separator operated at high vacuum via a set of cones. The ions are separate«! according to their mass/charge ratio in the mass Separator (quadrupole, magnetic sector field or time-of-flight mass Separator). In most cases, the ions are detected using a secondaiy electron multiplier; in some set-ups (also) a Faraday cup can be used. Single-collector (scanning mass spectrometer usually used for quantitative elemental analysis) or multicollector (static Operation of mass spectrometer for precise isotope ratio analysis) configurations can be found.
Technical background
(2015)
The major components of sector field instruments can be listed as follows and will be described in more detail in the following chapter. (Specific details for the different types of instruments will be given in the corresponding instrumental sections in Chapters 11-17.) The general principle of all mass spectrometers follows ionisation after sample introduction, Separation of the ions according to their mlz ratio and final detection at the detection unit. The transport and Separation of ions follow the principles of ion optics.
Measurement strategies
(2015)
Designing an appropriate measurement strategy for a particular analytical question is not always obvious, since a number of factors have to be considered, whereby some of them might be difficult to define. A set of key questions generally precede the experimental design in analytical measurements and help to choose the measurement strategy, which is fit for the intended use – in the particular case of the content of this book – either for quantification, elemental ratio or isotope ratio analyses, accordingly.
Prevention of damage caused by heat is one of the objectives during package safety evaluation. This chapter describes basics of heat transfer and major aspects of regulatory requirements. Package temperature criteria and fire test conditions are explained. Special package design features regarding material properties and safety evaluation concepts are discussed. Experimental fire testing is performed by pool fire or with the help of a furnace. Analysis by numerical or analytical approaches show temperature gradients and whether compliance with the regulatory requirements and specified design temperatures is met. The tightness of the package lid system influenced by geometry changes is in the focus of a holistic thermo-mechanical approach considering the entire mechanical and thermal load conditions according the regulatory requirements.
Thermal ionisation, also known as surface ionisation, was one of the first ionisation techniques developed for mass spectrometry, having been invented as early as 1918. The ionization process, described by the empirically derived “fractionation laws”, is widely understood. Isotope ratio measurements can be achieved with high precision and accuracy. Due to this, thermal ionisation has paved the way for great scientific achievements including: the discovery of new isotopes, the determination of radioactive half-lives and atomic weights of the elements, the accurate determination of the age of the earth and investigations on human society in the past such as mobility and trade. TIMS is still regarded as ‘golden standard’ in isotope ratio measurements. Thus the method is a reference technique that remains at the forefront of isotopic analysis particularly in the fields of metrology. A concise overview is given here of the technical background of thermal ionisation as well as the numerous applications of this technique in earth sciences, industry, metrology, and nuclear forensics.
A new technique to fix bioceramic powder on a titanium alloy by using femtosecond laser pulses is presented. It is shown that gentle fixation of a bioactive dielectric material on a metallic model implant is successful. This is potentially a new tool for the improvement of bone prostheses. An advantage of the ultrashort pulses is the very low heat influx into the whole sample. There is only a very thin interaction zone during the fixing, which is the metal surface in contact with the ceramic layer. Neither the fixed ceramic particles nor the major part of the metal suffer any modification. The stability of the model implant (ceramic on metal) is investigated by rotating bending fatigue tests. No indication of a reduction of the mechanical stability compared to untreated metallic reference samples was found.
Neutron imaging
(2016)
Neutron imaging methods are appropriate to investigate hydrogen distributions in several metallic systems. The large total neutron cross section of hydrogen compared to those of elements or isotopes, respectively, in usual structural materials like steels or zirconium alloys allows the detection even of small amounts of hydrogen in such materials. The dependence of the total macroscopic neutron cross section of the sample or component on the hydrogen concentration can be determined experimentally by means of calibration specimens with known hydrogen concentrations. Such a calibration allows for a full quantitative determination of the local hydrogen concentration with a spatial resolution better than 20 μm. Because neutron radiography is fast and non-destructive, in situ investigations of time-dependent processes like hydrogen absorption and release or hydrogen bulk diffusion can be performed. This chapter gives an introduction into the main neutron imaging methods, radiography and tomography, and gives as examples results of neutron imaging investigations of hydrogen in different steels and in zirconium alloys,respectively.
Cylinder valves for oxygen service that meet the standard DIN EN ISO 10297 should be safe, if properly handled by the user. In the last few years, however, the number of incidents with oxygen valves that has been reported to Federal Institute for Materials Research and Testing (BAM) has increased. According to the incident reports, incorrect handling can be ruled out. People were seriously injured and in most cases, the causes of these incidents were not clear. Very often, such incidents occurred during opening and closing of the valves. Therefore, the technical-scientific community has put the existing test methods for type testing more and more into question. Besides other mandatory tests, the above-mentioned standard allows to perform the endurance test with air or with nitrogen. This is appropriate for all other gases but not for oxygen. Up to now, this test does not consider the fact that cylinder valves also contain nonmetallic seat materials and lubricants that may react with oxygen in a dangerous way. Because of this unsatisfactory situation, BAM initiated a research project to perform endurance testing of cylinder valves for oxygen service much more practice related with oxygen. This test simulates very well real life situations when the cylinder valve is opened or closed. The first part of this project was the development of a new oxygen operated endurance tester in accordance with DIN EN ISO 10297. In a second part, endurance testing of valves with air and with oxygen was performed and the results were compared. In addition, another mandatory test of the standard, the oxygen pressure surge test was carried out on new valves and on valves that had undergone endurance tests with air or oxygen, to see the influence on the burn-out safety of such pre-stressed valves. This paper presents the main results of the project. The findings clearly speak for implementing the oxygen endurance test not only to DIN EN ISO 10297 but also to various other standards to increase the burn-out safety of oxygen cylinder valves.