Specialized Electrical Testing Methods

Electrical and Electronic. There are many industries where adhesives must perform several special functions in addition to their primary function of bonding or joining. These industries often have test methods, specifications, and nomenclature that are unique and somewhat foreign to adhesive formulators. One such industry is the electrical and electronic industry. 

The International Electrotechnical Commission (lEC) was founded in 1904 and is now affiliated with the International Organization for Standardization as a Technical Division. The lEC has a Technical Committee 15 on Electrical Insulating Materials, which is concerned with the standardization of testing methods and specifications in this special field. It met in Scheveningen, Netherlands, September 10 to 12,1952. Approved test methods and specifications are issued as recommendations and standards (16),... 

This chapter presents an overview of properties and performance of polymer blends. It is structured into nine sections dealing with aspects required for assessing the performance of a polymer blend. These are mechanical properties comprising of both low-speed and high-speed popularly studied properties chemical and solvent effects thermal and thermodynamic properties flammability electrical, optical, and sound transmission properties and some special test methods which assumed prominence recently because of their utility. 

This chapter presents an overview of properties and performance of polymer blends, focusing on these aspects that are outside the main domain of the other chapters in this handbook. Such properties as mechanical, chemical, and solvent effects and thermal, flame retardancy, electrical, and optical properties are discussed. Further, the developments in sound transmission, certain special test methods in aroma barrier, permeability test for hquids, and environment stress cracking are included in the second edition of this handbook. In addition, the data is updated and upgraded. And, finally, the relevant and useful websites for additional information are also provided towards the end of this chapter. 

With complex multilayer product, optical inspection will not be able to identify assem-bly/contamination-induced defects internal to the board in any case, and may still be limited in cases of contaminants or very fine-geometry shorts and opens on external layers. The equipment is somewhat slower than universal grid test systems, particularly when run at very high resolution. For such reasons, it is still not common practice to employ optical inspection (by itself) as a substitute for electrical testing. This may be a method that develops further in the future or that finds acceptance in special circumstances. 

The attempts to standardize the testing methods have led to the development of specialized standards for building materials, transportation and storage materials, electrical engineering, furniture and furnishings, etc. Other tests have been proposed for textiles, foams, road vehicles, streetcars, railways, aircraft, mining, and home furnishings. 

A special concern is contamination of viscous oils with polychlorinated biphenyls (PCBs). Electrical insulating oils require analysis before disposal to ensure the absence of PCBs. ASTM Test Method D6160, Determination of Polychlorinated Biphenyls (PCBs) in Waste Materials by Gas Chromatography, is a newly introduced and widely applicable method. Standard reference samples for nine commercial PCBs (Aroclors) are available. 

Many of the tests described as useful in identification are also run routinely as quality controls on known polymers. Although infrared (IR) spectroscopy is extremely helpful as an identification tool, it is also applied to the measurement of crystallinity and branching in some polymers (notably polyethylene). Physical testing, molecnlar weight determination, and electrical testing have been discussed previously. The larger polymer producers perform almost all of these tests routinely. The smaller, more specialized laboratories of many fabricators and consumers may not possess all of the instruments needed for these tests. Independent laboratories will perform them on a consulting basis. Where the instruments are expensive or the test method is quite involved, recourse to independent laboratories may be wise. 

The specimen may be a sheet of any size convenient to test, but should have uniform thickness. The test may be run at standard room temperature and humidity, or in special sets of conditions as desired. In any case, the specimens should be preconditioned to the set of conditions used. Electrodes are applied to opposite faces of the test specimen. The capacitance and dielectric loss are then measured by comparison or substitution methods in an electric bridge circuit. From these measurements and the dimensions of the specimen, dielectric constant and loss factor are computed. 

Some special approaches defined in the CE enantioseparation field can be found in References 37 and 38. In Reference 37, the authors tested four approaches to decrease the analysis time of a previously developed chiral separation method for amphetamine and its related compounds. The considered possibilities were (i) the short-end injection technique or (ii) increased electrical field combined with a capillary length reduction. 

In addition, the efficiency of electric contact between bipolar plates and gas diffusion layers was measured using special test station comprising a hydraulic press with a temperature control, current supply and control systems. The purpose of provided measurements is the comparative analysis of parameters of different bipolar plates and gas diffusion layers, and also obtaining of the necessary data for use in calculations on mathematical model. Resistance tests of gas diffusion layers and bipolar plates were performed both in a longitudinal direction (four-contact method) and in a transverse direction. 

The electrical conductivity of molten sulphur at temperatures up to 200 C has been studied on samples which were specially purified, as well as doped with impurities (paraffin, phenanthrene, benzidine, bromine, and iodine). The current flow below 160 C results from electrophoretically migrating impurities and, by interaction with the impurities, ionized molecules, whereas at higher temperatures conduction is caused by electrons. At the minimum of viscosity of the molten sulphur (154.5 °C) the conductivity shows a maximum, which is shifted by impurities (especially halogens) as much as 10 °C towards lower temperatures, llie effect on the mechanical properties of sulphur by the presence of has been studied. The preparation (3 methods), identification, and testing of are reported. Specimens with an content of more than 16% may be prepared by pouring hot sulphur into cold CSg. An analysis of the results of the study indicates that acts as a typical low-modulus material,... 

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