Materials and Specimen Preparation

Two different materials were chosen for the stiffer component (Material 2), polymethylmethacrylate (PMMA) and polycarbonate (PC). They were bonded to a much softer thermoplastic elastomer (TPE) (Material 1). The bulk mechanical 

Piacry] SG 90, Stickstoffwerk Pie.steritz (comparable to Plexiglas 7N, Degussa) 

Plates (80 mmx 80 nun x 2 mm) were produced by injection molding. From these plates, inlays for the injection molding tool were milled with different circular curvatures with radii r = a = 0.5,0.8,1.0,1.5,2.0,3.5,5.0 mm, and radii = 7.0 and 10.0 mm with a=5 nun rJa =1.4 and 2), as well as a flat interface with sharp edges at a width of 10 mm. The following geometrical parameters were used Ap = 1-2 mm. A, 10 mm, 2A = 13.5-16.5 mm, specimen thickness 2r = 2 mm. The testing speed was 5 nun/min. 

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Materials and Specimen Preparation. ABS 2 and ABS 3 were prepared by dry and melt blending of ABS 1 with a rigid polySAN. The styrene/acrylonitrile ratio of the polySAN used for blending was the same as that present in the parent ABS 1. Polydiene contents are in the order ABS 1 > ABS 2 > ABS 3. 

A recent review of the experimental situation has been given by Honig(1985). It is pointed out that the electrical properties, particularly near to the transition, are very sensitive to purity and specimen preparation, and that much of the extensive experimental work is therefore open to doubt. None the less, the broad features of the behaviour of this material are clear. The history of the so-called Verwey transition in this material goes back to 1926, when Parks and Kelly (1926) detected an anomalous peak near 120 K in the heat capacity of a natural crystal of magnetite. The first detailed investigations were those of Verwey and co-workers (Verwey 1939, Verwey and Haayman 1941, Verwey et al. 1947), who showed that there was a near discontinuity in the conductivity at about 160K. The conductivity as measured by Miles et al. (1957) is shown in Fig. 8.1. 

Mix and Specimen Preparation. Most of the mixes described in this paper were prepared from a fairly one-sized medium-coarse sand with 35% voids in the mineral aggregate and with only 2%% of the material finer than No. 200 mesh. The sand grading is included in Table I. A 150/200 penetration grade asphalt was used. 

Sampling Selection of materials and specimens, identification of population, selection of method/ sampling model, sample number/mass/size, sampling plan, collection techniques, compilation of logistics, preparation of tools, timing, meaningful and representative collection, minimization of contamination and analyte losses (here and in all other steps), conservation of spedation... 

Specimen preparation may be broadly classified into two main areas specimen preparation techniques for transmitted-light microscopy (thin sections, smears, fibers, particulate strews) and specimen preparation techniques for reflected-light microscopy (surface preparation of opaque and nearly opaque materials). However, they are by no means exclusive and, although metals, ores, and opaque minerals may be studied by reflected light only, thin sections, smears, etc., may be studied both by transmitted and by reflected light, e.g., transmitted-light and epifluorescence microscopy. The advantages of such dual observational techniques relate in particular to contrast enhancement (criterion (3)). 

Plummer [120] provided an excellent review in his reflections on the use of microtomy for materials science specimen preparation, with a table of material classes, references, and comments. The review includes examples of polymer composites, blends, membranes, elastomers, and coatings. Kink bands and shear deformation were shown in polybenzobisoxazole (PBO) fibers microtomed and studied by TEM [121]. Fibers treated to cause compressive deformation were taped to sheet polycarbonate and coated with spray acrylic to fix them to the substrate. Small sections (<5mm) attached to the polycarbonate were cut, trimmed, and microtomed to a thickness of 40-80nm with a new area of a diamond knife and picked up on 400 mesh grids. Ericson and Lindberg [122] showed that when the sample holder of the... 

The infonuation that can be extracted from inorganic samples depends mainly on tlie electron beam/specimen interaction and instrumental parameters [1], in contrast to organic and biological materials, where it depends strongly on specimen preparation. 

Microscopists in every technical field use the microscope to characterize, compare, and identify a wide variety of substances, eg, protozoa, bacteria, vimses, and plant and animal tissue, as well as minerals, building materials, ceramics, metals, abrasives, pigments, foods, dmgs, explosives, fibers, hairs, and even single atoms. In addition, microscopists help to solve production and process problems, control quaUty, and handle trouble-shooting problems and customer complaints. Microscopists also do basic research in instmmentation, new techniques, specimen preparation, and appHcations of microscopy. The areas of appHcation include forensic trace evidence, contamination analysis, art conservation and authentication, and asbestos control, among others. 

ISO/DIS 1874-2, Plastics Polyamide (PM) Moulding and Extrusion Materials, Part 2 Preparation of Test Specimens and Determination of Properties, International Standards Organization, Geneva, Switzedand, 1994. 

K. C. Thompson-Russell and J. W. Edington. Electron Microscope Specimen Preparation Techniques in Materials Science. Monographs in Practical Electron Microscopy, No. 5- Philips Technical Library, Eindhoven Delaware, 1977. 

Speciman Preparation for Transmission Electron Microscopy of Materials (J. C. Brauman, R. M. Anderson, and M. L. McDonald, eds.) MRS Symp. Proc vol. 115, Materials Research Society, Pittsburg, 1988. This conference proceedings contains many up-to-date methods as well as references to books on various aspects of specimen preparation. 

S. Amelincks, D. van Dyck, J. van Landuyt, G. van Tendeloo (eds.) Electron Microscopy Principles and Fundamentals,VCH Verlagsgesellschaft mbH, Weinheim 1997. 2-178 R. M. Anderson, S. D. Walck (eds.) Specimen Preparation for Transmission Electron Microscopy of Materials IV, Materials Research Society, Pittsbrrrgh 1997. 

These latter curves are particularly important when they are obtained experimentally because they are less time consuming and require less specimen preparation than creep curves. Isochronous graphs at several time intervals can also be used to build up creep curves and indicate areas where the main experimental creep programme could be most profitably concentrated. They are also popular as evaluations of deformational behaviour because the data presentation is similar to the conventional tensile test data referred to in Section 2.3. It is interesting to note that the isochronous test method only differs from that of a conventional incremental loading tensile test in that (a) the presence of creep is recognised, and (b) the memory which the material has for its stress history is accounted for by the recovery periods. 

The metal electrode to be studied must be carefully prepared, attached to an electrical lead and mounted so that a known surface area of one face is presented to the solution. Several procedures are used such as mounting in a cold setting resin (Araldite) or inserting into a close-fitting holder of p.t.f.e. In the case of metal-solution systems that have a propensity for pitting care must be taken to avoid a crevice at the interface between metal specimen and the mounting material, and this can be achieved effectively by mounting the... 

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